Publications

@article{nokey,

title = {Radial bound states in the continuum for polarization-invariant nanophotonics},

author = {L K\"{u}hner and L Sortino and R Bert\'{e} and J Wang and H Ren and S A Maier and Y S Kivshar and A Tittl},

url = {https://arxiv.org/abs/2206.05206},

doi = {https://doi.org/10.48550/arXiv.2206.05206},

year  = {2022},

date = {2022-06-10},

journal = {arXiv preprint arXiv:2206.05206},

abstract = {All-dielectric nanophotonics underpinned by bound states in the continuum (BICs) have demonstrated breakthrough applications in nanoscale light manipulation, frequency conversion and optical sensing. Leading BIC implementations range from isolated nanoantennas with localized electromagnetic fields to symmetry-protected metasurfaces with controllable resonance quality (Q) factors. However, they either require structured light illumination with complex beamshaping optics or large, fabrication-intense arrays of polarization-sensitive unit cells, hindering tailored nanophotonic applications and on-chip integration. Here, we introduce radial quasi bound states in the continuum (rBICs) as a new class of radially distributed electromagnetic modes controlled by structural asymmetry in a ring of dielectric rod pair resonators. The rBIC platform provides polarization-invariant and tunable high-Q resonances with strongly enhanced near-fields in an ultracompact footprint as low as 2 μm2. We demonstrate rBIC realizations in the visible for sensitive biomolecular detection and enhanced second-harmonic generation from monolayers of transition metal dichalcogenides, opening new perspectives for compact, spectrally selective, and polarization-invariant metadevices for multi-functional light-matter coupling, multiplexed sensing, and high-density on-chip photonics.},

keywords = {Foundry Inorganic, Molecularly-Functionalized},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Light-driven molecular motors embedded in covalent organic frameworks},

author = {C St\"{a}hler and L Grunenberg and M W Terban and W R Browne and D Doellerer and M Kathan and M Etter and B V Lotsch and B L Feringa and S Krause},

url = {http://dx.doi.org/10.1039/D2SC02282F},

doi = {10.1039/D2SC02282F},

issn = {2041-6520},

year  = {2022},

date = {2022-06-02},

journal = {Chemical Science},

abstract = {The incorporation of molecular machines into the backbone of porous framework structures will facilitate nano actuation, enhanced molecular transport, and other out-of-equilibrium host\textendashguest phenomena in well-defined 3D solid materials. In this work, we detail the synthesis of a diamine-based light-driven molecular motor and its incorporation into a series of imine-based polymers and covalent organic frameworks (COF). We study structural and dynamic properties of the molecular building blocks and derived self-assembled solids with a series of spectroscopic, diffraction, and theoretical methods. Using an acid-catalyzed synthesis approach, we are able to obtain the first crystalline 2D COF with stacked hexagonal layers that contains 20 mol% molecular motors. The COF features a specific pore volume and surface area of up to 0.45 cm3 g−1 and 604 m2 g−1, respectively. Given the molecular structure and bulkiness of the diamine motor, we study the supramolecular assembly of the COF layers and detail stacking disorders between adjacent layers. We finally probe the motor dynamics with in situ spectroscopic techniques revealing current limitations in the analysis of these new materials and derive important analysis and design criteria as well as synthetic access to new generations of motorized porous framework materials.},

keywords = {Foundry Organic, Molecularly-Functionalized},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {All-optical nanoscopic spatial control of molecular reaction yields on nanoparticles},

author = {W Zhang and R Dagar and P Rosenberger and A Sousa-Castillo and M Neuhaus and W Li and S A Khan and A S Alnaser and E Cortes and S A Maier and C Costa-Vera and M F Kling and B Bergues},

url = {http://opg.optica.org/optica/abstract.cfm?URI=optica-9-5-551},

doi = {10.1364/OPTICA.453915},

year  = {2022},

date = {2022-05-20},

journal = {Optica},

volume = {9},

number = {5},

pages = {551-560},

abstract = {Molecular adsorbate reactions on nanoparticles play a fundamental role in areas such as nano-photocatalysis, atmospheric, and astrochemistry. They can be induced, enhanced, and controlled by field localization and enhancement on the nanoparticle surface. In particular, the ability to perform highly controlled near-field-mediated reactions is key to deepening our understanding of surface photoactivity on nanosystems. Here, using reaction nanoscopy, we experimentally demonstrate all-optical nanoscopic control of surface reaction yields by tailoring the near fields on nanoparticles with waveform-controlled linear and bicircular two-color laser pulses, respectively. We observe site-selective proton emission from the dissociative ionization of adsorbate molecules on SiO2 nanoparticles as a function of the polarization and relative phase of the two-color pulses. The angularly resolved close-to-uniform mapping between the surface reaction yields and the measured ion momentum enables the observation and spatial control of molecular reactions on the nanoparticle surface with nanoscopic resolution. The experimental results are modeled and reproduced qualitatively by classical trajectory Monte Carlo simulations. Our work paves the way toward reliable all-optical control of photocatalytic chemical reactions on nanoscale surfaces.},

keywords = {Molecularly-Functionalized, Solid-Solid},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Controlling Plasmonic Chemistry Pathways through Specific Ion Effects},

author = {A Stefancu and L Nan and L Zhu and V Chiș and I Bald and M Liu and N Leopold and S A Maier and E Cortes},

url = {https://onlinelibrary.wiley.com/doi/abs/10.1002/adom.202200397},

doi = {https://doi.org/10.1002/adom.202200397},

issn = {2195-1071},

year  = {2022},

date = {2022-05-11},

journal = {Advanced Optical Materials},

volume = {n/a},

number = {n/a},

pages = {2200397},

abstract = {Abstract Plasmon-driven dehalogenation of brominated purines has been recently explored as a model system to understand fundamental aspects of plasmon-assisted chemical reactions. Here, it is shown that divalent Ca2+ ions strongly bridge the adsorption of bromoadenine (Br-Ade) to Ag surfaces. Such ion-mediated binding increases the molecule's adsorption energy leading to an overlap of the metal energy states and the molecular states, enabling the chemical interface damping (CID) of the plasmon modes of the Ag nanostructures (i.e., direct electron transfer from the metal to Br-Ade). Consequently, the conversion of Br-Ade to adenine almost doubles following the addition of Ca2+. These experimental results, supported by theoretical calculations of the local density of states of the Ag/Br-Ade complex, indicate a change of the charge transfer pathway driving the dehalogenation reaction, from Landau damping (in the lack of Ca2+ ions) to CID (after the addition of Ca2+). The results show that the surface dynamics of chemical species (including water molecules) play an essential role in charge transfer at plasmonic interfaces and cannot be ignored. It is envisioned that these results will help in designing more efficient nanoreactors, harnessing the full potential of plasmon-assisted chemistry.},

keywords = {Molecularly-Functionalized, Solid-Liquid},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Introducing a Symmetry-Breaking Coupler into a Dielectric Metasurface Enables Robust High-Q Quasibound States in the Continuum and Efficient Nonlinear Frequency Conversion},

author = {G Q Moretti and A Tittl and E Cort\'{e}s and S A Maier and A V Bragas and G Grinblat},

url = {https://doi.org/10.48550/arXiv.2204.07097},

doi = {https://doi.org/10.48550/arXiv.2204.07097},

year  = {2022},

date = {2022-04-14},

journal = {arXiv preprint arXiv:2204.07097},

abstract = {Dielectric metasurfaces supporting quasi-bound states in the continuum (quasi-BICs) exhibit very high quality factor resonances and electric field confinement. However, accessing the high-Q end of the quasi-BIC regime usually requires marginally distorting the metasurface design from a BIC condition, pushing the needed nanoscale fabrication precision to the limit. This work introduces a novel concept for generating high-Q quasi-BICs, which strongly relaxes this requirement by incorporating a relatively large perturbative element close to high-symmetry points of an undistorted BIC metasurface, acting as a coupler to the radiation continuum. We validate this approach by adding a ∼100 nm diameter cylinder between two reflection-symmetry points separated by a 300 nm gap in an elliptical disk metasurface unit cell, using gallium phosphide as the dielectric. We find that high-Q resonances emerge when the cylindrical coupler is placed at any position between such symmetry points. We further explore this metasurface's second harmonic generation capability in the optical range. Displacing the coupler as much as a full diameter from a BIC condition produces record-breaking normalized conversion efficiencies >102 W−1. The strategy of enclosing a disruptive element between multiple high-symmetry points in a BIC metasurface could be applied to construct robust high-Q quasi-BICs in many geometrical designs.},

keywords = {Foundry Inorganic, Molecularly-Functionalized},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Trends in Nanophotonics-Enabled Optofluidic Biosensors},

author = {J Wang and S A Maier and A Tittl},

url = {https://onlinelibrary.wiley.com/doi/abs/10.1002/adom.202102366},

doi = {https://doi.org/10.1002/adom.202102366},

issn = {2195-1071},

year  = {2022},

date = {2022-02-22},

journal = {Advanced Optical Materials},

volume = {n/a},

number = {n/a},

pages = {2102366},

abstract = {Abstract Optofluidic sensors integrate photonics with micro/nanofluidics to realize compact devices for the label-free detection of molecules and the real-time monitoring of dynamic surface binding events with high specificity, ultrahigh sensitivity, low detection limit, and multiplexing capability. Nanophotonic structures composed of metallic and/or dielectric building blocks excel at focusing light into ultrasmall volumes, creating enhanced electromagnetic near-fields ideal for amplifying the molecular signal readout. Furthermore, fluidic control on small length scales enables precise tailoring of the spatial overlap between the electromagnetic hotspots and the analytes, boosting light-matter interaction, and can be utilized to integrate advanced functionalities for the pre-treatment of samples in real-world-use cases, such as purification, separation, or dilution. In this review, the authors highlight current trends in nanophotonics-enabled optofluidic biosensors for applications in the life sciences while providing a detailed perspective on how these approaches can synergistically amplify the optical signal readout and achieve real-time dynamic monitoring, which is crucial in biomedical assays and clinical diagnostics.},

keywords = {Molecularly-Functionalized},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Low-Temperature and Water-Based Biotemplating of Nanostructured Foam-Like Titania Films Using \ss-Lactoglobulin},

author = {J E Heger and W Chen and S Yin and N Li and V K\"{o}rstgens and C J Brett and W Ohm and S V Roth and P M\"{u}ller-Buschbaum},

url = {https://onlinelibrary.wiley.com/doi/abs/10.1002/adfm.202113080},

doi = {https://doi.org/10.1002/adfm.202113080},

issn = {1616-301X},

year  = {2022},

date = {2022-02-17},

journal = {Advanced Functional Materials},

volume = {n/a},

number = {n/a},

pages = {2113080},

abstract = {Abstract Given the broad use of nanostructured crystalline titania films, an environmentally friendly and more sustainable synthesis route is highly desirable. Here, a water-based, low-temperature route is presented to synthesize nanostructured foam-like crystalline titania films. A pearl necklace-like nanostructure is introduced as tailored titania morphology via biotemplating with the use of the major bovine whey protein \ss-lactoglobulin (\ss-lg). It is shown that titania crystallization in a brookite-anatase mixed phase is promoted via spray deposition at a comparatively low temperature of 120 °C. The obtained crystallites have an average grain size of (4.2 ± 0.3) nm. In situ grazing incidence small-angle and wide-angle X-ray scattering (GISAXS/GIWAXS) are simultaneously performed to understand the kinetics of film formation and the templating role of \ss-lg during spray coating. In the \ss-lg:titania biohybrid composites, the crystal growth in semicrystalline titania clusters is sterically directed by the condensing \ss-lg biomatrix. Due to using spray coating, the green chemistry approach to titania-based functional films can be scaled up on a large scale, which can potentially be used in photocatalytic processes or systems related to energy application.},

keywords = {Foundry Inorganic, Molecularly-Functionalized},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Halide\textendashMetal Complexes at Plasmonic Interfaces Create New Decay Pathways for Plasmons and Excited Molecules},

author = {A Stefancu and O M Biro and O Todor-Boer and I Botiz and E Cort\'{e}s and N Leopold},

url = {https://doi.org/10.1021/acsphotonics.1c01714},

doi = {10.1021/acsphotonics.1c01714},

year  = {2022},

date = {2022-02-10},

journal = {ACS Photonics},

abstract = {We show that by modifying the chemical interface of silver nanoparticles (AgNPs) with halide ions, it is possible to tune the total decay rate of adsorbed excited molecules and the plasmon damping rate. Through single-molecule surface-enhanced Raman scattering and surface-enhanced fluorescence enhancement factors of crystal violet (CV) and rhodamine 6G (R6G), we show that I\textendash-modified AgNPs (AgNPs@I) and Br\textendash-modified AgNPs (AgNPs@Br) lead to an increase in the total decay rate of excited CV and R6G by a factor between ∼1.6\textendash2.6, compared to Cl\textendash-modified AgNPs (AgNPs@Cl). In addition, we found that the chemical interface damping, which characterizes the plasmon resonance decay into surface states, is stronger on AgNPs@I and AgNPs@Br when compared to AgNPs@Cl. These results point toward the formation of metal\textendashhalide surface complexes. These new interfacial states can accept electrons from both excited molecular orbitals and surface plasmon excitations, completely altering the electronic dynamics and reactivity of plasmonic interfaces.},

keywords = {Foundry Inorganic, Molecularly-Functionalized},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Quantitative Single-Molecule Measurements of Membrane Charges with DNA Origami Sensors},

author = {S E Ochmann and T Schr\"{o}der and C M Schulz and P Tinnefeld},

url = {https://doi.org/10.1021/acs.analchem.1c05092},

doi = {10.1021/acs.analchem.1c05092},

issn = {0003-2700},

year  = {2022},

date = {2022-01-28},

journal = {Analytical Chemistry},

abstract = {Charges in lipid head groups generate electrical surface potentials at cell membranes, and changes in their composition are involved in various signaling pathways, such as T-cell activation or apoptosis. Here, we present a DNA origami-based sensor for membrane surface charges with a quantitative fluorescence read-out of single molecules. A DNA origami plate is equipped with modifications for specific membrane targeting, surface immobilization, and an anionic sensing unit consisting of single-stranded DNA and the dye ATTO542. This unit is anchored to a lipid membrane by the dye ATTO647N, and conformational changes of the sensing unit in response to surface charges are read out by fluorescence resonance energy transfer between the two dyes. We test the performance of our sensor with single-molecule fluorescence microscopy by exposing it to differently charged large unilamellar vesicles. We achieve a change in energy transfer of ∼10% points between uncharged and highly charged membranes and demonstrate a quantitative relation between the surface charge and the energy transfer. Further, with autocorrelation analyses of confocal data, we unravel the working principle of our sensor that is switching dynamically between a membrane-bound state and an unbound state on the timescale of 1\textendash10 ms. Our study introduces a complementary sensing system for membrane surface charges to previously published genetically encoded sensors. Additionally, the single-molecule read-out enables investigations of lipid membranes on the nanoscale with a high spatial resolution circumventing ensemble averaging.},

keywords = {Foundry Organic, Molecularly-Functionalized},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Hybrid Plasmonic Nanomaterials for Hydrogen Generation and Carbon Dioxide Reduction},

author = {S Ezendam and M Herran and L Nan and C Gruber and Y Kang and F Gr\"{o}bmeyer and R Lin and J Gargiulo and A Sousa-Castillo and E Cort\'{e}s},

url = {https://doi.org/10.1021/acsenergylett.1c02241},

doi = {10.1021/acsenergylett.1c02241},

year  = {2022},

date = {2022-01-24},

urldate = {2022-01-24},

journal = {ACS Energy Letters},

pages = {778-815},

abstract = {The successful development of artificial photosynthesis requires finding new materials able to efficiently harvest sunlight and catalyze hydrogen generation and carbon dioxide reduction reactions. Plasmonic nanoparticles are promising candidates for these tasks, due to their ability to confine solar energy into molecular regions. Here, we review recent developments in hybrid plasmonic photocatalysis, including the combination of plasmonic nanomaterials with catalytic metals, semiconductors, perovskites, 2D materials, metal\textendashorganic frameworks, and electrochemical cells. We perform a quantitative comparison of the demonstrated activity and selectivity of these materials for solar fuel generation in the liquid phase. In this way, we critically assess the state-of-the-art of hybrid plasmonic photocatalysts for solar fuel production, allowing its benchmarking against other existing heterogeneous catalysts. Our analysis allows the identification of the best performing plasmonic systems, useful to design a new generation of plasmonic catalysts.},

keywords = {Molecularly-Functionalized, Solid-Liquid},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Light-driven carbon nitride microswimmers with propulsion in biological and ionic media and responsive on-demand drug delivery},

author = {V Sridhar and F Podjaski and Y Alapan and J Kr\"{o}ger and L Grunenberg and V Kishore and B V Lotsch and M Sitti},

url = {https://www.science.org/doi/abs/10.1126/scirobotics.abm1421},

doi = {doi:10.1126/scirobotics.abm1421},

year  = {2022},

date = {2022-01-19},

journal = {Science Robotics},

volume = {7},

number = {62},

pages = {eabm1421},

abstract = {We propose two-dimensional poly(heptazine imide) (PHI) carbon nitride microparticles as light-driven microswimmers in various ionic and biological media. Their high-speed (15 to 23 micrometer per second; 9.5 ± 5.4 body lengths per second) swimming in multicomponent ionic solutions with concentrations up to 5 M and without dedicated fuels is demonstrated, overcoming one of the bottlenecks of previous light-driven microswimmers. Such high ion tolerance is attributed to a favorable interplay between the particle’s textural and structural nanoporosity and optoionic properties, facilitating ionic interactions in solutions with high salinity. Biocompatibility of these microswimmers is validated by cell viability tests with three different cell lines and primary cells. The nanopores of the swimmers are loaded with a model cancer drug, doxorubicin (DOX), resulting in a high (185%) loading efficiency without passive release. Controlled drug release is reported under different pH conditions and can be triggered on-demand by illumination. Light-triggered, boosted release of DOX and its active degradation products are demonstrated under oxygen-poor conditions using the intrinsic, environmentally sensitive and light-induced charge storage properties of PHI, which could enable future theranostic applications in oxygen-deprived tumor regions. These organic PHI microswimmers simultaneously address the current light-driven microswimmer challenges of high ion tolerance, fuel-free high-speed propulsion in biological media, biocompatibility, and controlled on-demand cargo release toward their biomedical, environmental, and other potential applications.},

keywords = {Foundry Inorganic, Molecularly-Functionalized},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Band Gap Control and Properties of Indium\textendashZinc Oxynitride Thin Films Grown by Molecular Beam Epitaxy},

author = {M Kraut and E Sirotti and F Pantle and T Hoffmann and M Stutzmann},

url = {https://doi.org/10.1021/acs.jpcc.1c08630},

doi = {10.1021/acs.jpcc.1c08630},

issn = {1932-7447},

year  = {2022},

date = {2022-01-19},

urldate = {2022-01-19},

journal = {The Journal of Physical Chemistry C},

volume = {126},

number = {4},

pages = {2070-2077},

abstract = {The material system of II\textendashIII oxynitride semiconductors has opened new prospects in solar energy harvesting and photocatalysis in recent years due to a tunable band gap and favorable band edge positions with respect to important redox levels. A promising member of this family is In\textendashZn\textendashO\textendashN (IZNO), as its band gap can be tailored to lower values compared to its better studied cousin Ga\textendashZn\textendashO\textendashN. We study IZNO thin films grown on sapphire substrates by molecular beam epitaxy (MBE) and investigate their structural, surface morphology, optical absorption, and photoemission characteristics. We investigate the influence of the constituting elements in the alloy on the position of valence band maxima, conduction band minima, and the structural properties. Through precise variation of the composition, samples with a band gap range between 1.0 and 2.6 eV have been deposited and analyzed. Based on our results, Zn and N have been identified to lower the energy of valence and conduction band edges with respect to the vacuum level, while In and O have the opposite effect. Structural characterization reveals that the samples are polycrystalline with grain sizes of about 30 nm, comprising a mixture of cubic and hexagonal crystal phases with distinct short-range disorder. While in the ternary compounds In\textendashO\textendashN and Zn\textendashO\textendashN metal\textendashoxide bonds are dominant, we elucidate the formation of metal\textendashoxynitride bonds in IZNO. Electrical and optical measurements reveal charge carrier concentrations of 1018\textendash1020 cm\textendash3 and absorption coefficients of 105 cm\textendash1 above about 2 eV excitation energy, accompanied by pronounced free carrier absorption found in samples in the upper carrier concentration range in the infrared energy region. Typical Urbach energies are 80\textendash220 meV, with no clear correlation with the elemental composition. By introducing MBE growth for IZNO, we overcome the limitations typically inflicted by the fabrication methods on stoichiometric InN:ZnO solid solutions and provide unprecedented access to new compounds in this material class.},

keywords = {Molecularly-Functionalized},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Nickel polyphthalocyanine with electronic localization at the nickel site for enhanced CO2 reduction reaction},

author = {K Chen and M Cao and G Ni and S Chen and H Liao and L Zhu and H Li and J Fu and J Hu and E Cort\'{e}s and M Liu},

url = {https://www.sciencedirect.com/science/article/pii/S0926337322000339},

doi = {https://doi.org/10.1016/j.apcatb.2022.121093},

issn = {0926-3373},

year  = {2022},

date = {2022-01-09},

journal = {Applied Catalysis B: Environmental},

volume = {306},

pages = {121093},

abstract = {Nickel phthalocyanine (NiPc) can be at first glance a compelling catalyst for CO2 reduction reaction (CO2RR) because of its Ni\textendashN4 site. Unfortunately, the pristine NiPc possesses a low catalytic activity resulting from the poor CO2 adsorption and activation capabilities of the electron-deficiency Ni site. Herein, we develop nickel polyphthalocyanine (NiPPc) with extended conjugation to tailor the electronic density at the Ni active site. The enlarged π conjugation of NiPPc evokes the d-electrons localization, increasing the electronic density at the Ni site, which enhances its CO2 adsorption and activation. Consequently, NiPPc supported on carbon nanotubes (NiPPc/CNT) in a flow cell delivers an excellent activity of −300 mA cm−2 for CO2RR with the CO selectivity of 99.8%, which is much higher than that of NiPc dispersed on carbon nanotubes. NiPPc/CNT exhibits an outstanding stability for CO2RR of more than 30 h at a current density of −100 mA cm−2 with an ultrahigh selectivity for CO, exceeding 99.7%. This work showcases a new way of tuning the electronic density of catalytic sites.},

keywords = {Foundry Organic, Molecularly-Functionalized},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Influence of Layer Slipping on Adsorption of Light Gases in Covalent Organic Frameworks: A Combined Experimental and Computational Study},

author = {C Kessler and R Schuldt and S Emmerling and B V Lotsch and J K\"{a}stner and J Gross and N Hansen},

doi = {arXiv:2112.10137v1},

year  = {2021},

date = {2021-12-19},

urldate = {2021-12-19},

journal = {arXiv e-prints},

pages = {arXiv: 2112.10137},

abstract = {Sorption of gases in micro- and mesoporous materials is typically interpreted on the basis of idealized structural models where real structure effects such as defects and disorder are absent. For covalent organic frameworks (COFs) significant discrepancies between measured and simulated adsorption isotherms are often reported but rarely traced back to their origins. This is because little is known about the real structure of COFs and its effect on the sorption properties of these materials. In the present work molecular simulations are used to obtain adsorption isotherms of argon, nitrogen, and carbon dioxide in the COF-LZU1 at various temperatures. The (perfect) model COF has a BET surface that is higher than the experimental BET surface by a factor of approximately 1.33, suggesting defects or inclusions are present in the real structure. We find that the saturation adsorption loading of small gaseous species in COF-LZU1, as determined from grand canonical Monte Carlo simulations, is also higher by approximately the same factor compared to the experimental saturation loading. The influence of interlayer slipping on the shape of the adsorption isotherm and the adsorption capacity is studied. Comparison between simulation and experiment at lower loadings suggests the layers to be shifted instead of perfectly eclipsed. The sensitivity of the adsorption isotherms in this regime towards the underlying framework topology shows that real structure effects have significant influence on the gas uptake. Accounting for layer slipping is important to applications such as catalysis, gas storage and separation.},

keywords = {Foundry Inorganic, Molecularly-Functionalized},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Olefin Metathesis in Confinement: Towards Covalent Organic Framework Scaffolds for Increased Macrocyclization Selectivity},

author = {S T Emmerling and F Ziegler and F R Fischer and R Schoch and M Bauer and B Plietker and M R Buchmeiser and B V Lotsch},

url = {https://chemistry-europe.onlinelibrary.wiley.com/doi/abs/10.1002/chem.202104108},

doi = {https://doi.org/10.1002/chem.202104108},

issn = {0947-6539},

year  = {2021},

date = {2021-12-09},

urldate = {2021-12-09},

journal = {Chemistry \textendash A European Journal},

volume = {n/a},

number = {n/a},

pages = {e202104108},

abstract = {Abstract Covalent organic frameworks (COFs) offer vast structural and chemical diversity enabling a wide and growing range of applications. While COFs are well-established as heterogeneous catalysts, so far, their high and ordered porosity has scarcely been utilized to its full potential when it comes to spatially confined reactions in COF pores to alter the outcome of reactions. Here, we present a highly porous and crystalline, large-pore COF as catalytic support in α,ω-diene ring-closing metathesis reactions, leading to increased macrocyclization selectivity. COF pore-wall modification by immobilization of a Grubbs-Hoveyda-type catalyst via a mild silylation reaction provides a molecularly precise heterogeneous olefin metathesis catalyst. An increased macro(mono)cyclization (MMC) selectivity over oligomerization (O) for the heterogeneous COF-catalyst (MMC:O=1.35) of up to 51 % compared to the homogeneous catalyst (MMC:O=0.90) was observed along with a substrate-size dependency in selectivity, pointing to diffusion limitations induced by the pore confinement.},

keywords = {Foundry Organic, Molecularly-Functionalized},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Conductivity Mechanism in Ionic 2D Carbon Nitrides: From Hydrated Ion Motion to Enhanced Photocatalysis},

author = {J Kr\"{o}ger and F Podjaski and G Savasci and I Moudrakovski and A Jim\'{e}nez-Solano and M W Terban and S Bette and V Duppel and M Joos and A Senocrate and R Dinnebier and C Ochsenfeld and B V Lotsch},

url = {https://onlinelibrary.wiley.com/doi/abs/10.1002/adma.202107061},

doi = {https://doi.org/10.1002/adma.202107061},

issn = {0935-9648},

year  = {2021},

date = {2021-12-06},

journal = {Advanced Materials},

volume = {34},

number = {7},

pages = {2107061},

abstract = {Abstract Carbon nitrides are among the most studied materials for photocatalysis; however, limitations arise from inefficient charge separation and transport within the material. Here, this aspect is addressed in the 2D carbon nitride poly(heptazine imide) (PHI) by investigating the influence of various counterions, such as M = Li+, Na+, K+, Cs+, Ba2+, NH4+, and tetramethyl ammonium, on the material's conductivity and photocatalytic activity. These ions in the PHI pores affect the stacking of the 2D layers, which further influences the predominantly ionic conductivity in M-PHI. Na-containing PHI outperforms the other M-PHIs in various relative humidity (RH) environments (0\textendash42%RH) in terms of conductivity, likely due to pore-channel geometry and size of the (hydrated) ion. With increasing RH, the ionic conductivity increases by 4\textendash5 orders of magnitude (for Na-PHI up to 10-5 S cm-1 at 42%RH). At the same time, the highest photocatalytic hydrogen evolution rate is observed for Na-PHI, which is mirrored by increased photogenerated charge-carrier lifetimes, pointing to efficient charge-carrier stabilization by, e.g., mobile ions. These results indicate that also ionic conductivity is an important parameter that can influence the photocatalytic activity. Besides, RH-dependent ionic conductivity is of high interest for separators, membranes, or sensors.},

keywords = {Foundry Inorganic, Molecularly-Functionalized},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Local Growth Mediated by Plasmonic Hot Carriers: Chirality from Achiral Nanocrystals Using Circularly Polarized Light},

author = {L V Besteiro and A Movsesyan and O \'{A}valos-Ovando and S Lee and E Cort\'{e}s and M A Correa-Duarte and Z M Wang and A O Govorov},

url = {https://doi.org/10.1021/acs.nanolett.1c03503},

doi = {10.1021/acs.nanolett.1c03503},

issn = {1530-6984},

year  = {2021},

date = {2021-12-03},

journal = {Nano Letters},

abstract = {Plasmonic nanocrystals and their assemblies are excellent tools to create functional systems, including systems with strong chiral optical responses. Here we study the possibility of growing chiral plasmonic nanocrystals from strictly nonchiral seeds of different types by using circularly polarized light as the chirality-inducing mechanism. We present a novel theoretical methodology that simulates realistic nonlinear and inhomogeneous photogrowth processes in plasmonic nanocrystals, mediated by the excitation of hot carriers that can drive surface chemistry. We show the strongly anisotropic and chiral growth of oriented nanocrystals with lowered symmetry, with the striking feature that such chiral growth can appear even for nanocrystals with subwavelength sizes. Furthermore, we show that the chiral growth of nanocrystals in solution is fundamentally challenging. This work explores new ways of growing monolithic chiral plasmonic nanostructures and can be useful for the development of plasmonic photocatalysis and fabrication technologies.},

keywords = {Foundry Inorganic, Molecularly-Functionalized},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Ligand Engineering in Nickel Phthalocyanine to Boost the Electrocatalytic Reduction of CO2},

author = {K Chen and M Cao and Y Lin and J Fu and H Liao and Y Zhou and H Li and X Qiu and J Hu and X Zheng and M Shakouri and Q Xiao and Y Hu and J Li and J Liu and E Cort\'{e}s and M Liu},

url = {https://onlinelibrary.wiley.com/doi/abs/10.1002/adfm.202111322},

doi = {https://doi.org/10.1002/adfm.202111322},

issn = {1616-301X},

year  = {2021},

date = {2021-12-01},

urldate = {2021-12-01},

journal = {Advanced Functional Materials},

volume = {n/a},

number = {n/a},

pages = {2111322},

abstract = {Abstract Designing and synthesizing efficient molecular catalysts may unlock the great challenge of controlling the CO2 reduction reaction (CO2RR) with molecular precision. Nickel phthalocyanine (NiPc) appears as a promising candidate for this task due to its adjustable Ni active-site. However, the pristine NiPc suffers from poor activity and stability for CO2RR owing to the poor CO2 adsorption and activation at the bare Ni site. Here, a ligand-tuned strategy is developed to enhance the catalytic performance and unveil the ligand effect of NiPc on CO2RR. Theoretical calculations and experimental results indicate that NiPc with electron-donating substituents (hydroxyl or amino) can induce electronic localization at the Ni site which greatly enhances the CO2 adsorption and activation. Employing the optimal catalyst\textemdashan amino-substituted NiPc\textemdashto convert CO2 into CO in a flow cell can achieve an ultrahigh activity and selectivity of 99.8% at current densities up to −400 mA cm−2. This work offers a novel strategy to regulate the electronic structure of active sites by ligand design and discloses the ligand-directed catalysis of the tailored NiPc for highly efficient CO2RR.},

keywords = {Foundry Organic, Molecularly-Functionalized},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Emerging MXene@Metal\textendashOrganic Framework Hybrids: Design Strategies toward Versatile Applications},

author = {H Saini and N Srinivasan and V \v{S}edajov\'{a} and M Majumder and D P Dubal and M Otyepka and R Zbo\v{r}il and N Kurra and R A Fischer and K Jayaramulu},

url = {https://doi.org/10.1021/acsnano.1c06402},

doi = {10.1021/acsnano.1c06402},

issn = {1936-0851},

year  = {2021},

date = {2021-11-18},

journal = {ACS Nano},

volume = {15},

number = {12},

pages = {18742-18776},

abstract = {Rapid progress on developing smart materials and design of hybrids is motivated by pressing challenges associated with energy crisis and environmental remediation. While emergence of versatile classes of nanomaterials has been fascinating, the real excitement lies in the design of hybrid materials with tunable properties. Metal\textendashorganic frameworks (MOFs) are the key materials for gas sorption and electrochemical applications, but their sustainability is challenged by limited chemical stability, poor electrical conductivity, and intricate, inaccessible pores. Despite tremendous efforts towards improving the stability of MOF materials, little progress has made researchers inclined toward developing hybrid materials. MXenes, a family of two-dimensional transition-metal carbides, nitrides and carbonitrides, are known for their compositional versatility and formation of a range of structures with rich surface chemistry. Hybridization of MOFs with functional layered MXene materials may be beneficial if the host structure provides appropriate interactions for stabilizing and improving the desired properties. Recent efforts have focused on integrating Ti3C2Tx and V2CTx MXenes with MOFs to result in hybrid materials with augmented electrochemical and physicochemical properties, widening the scope for emerging applications. This review discusses the potential design strategies of MXene@MOF hybrids, attributes of tunable properties in the resulting hybrids, and their applications in water treatment, sensing, electrochemical energy storage, smart textiles, and electrocatalysis. Comprehensive discussions on the recent efforts on rapidly evolving MXene@MOF materials for various applications and potential future directions are highlighted.},

keywords = {Foundry Inorganic, Molecularly-Functionalized},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {A flavin-inspired covalent organic framework for photocatalytic alcohol oxidation},

author = {S Trenker and L Grunenberg and T Banerjee and G Savasci and L M Poller and K I M Muggli and F Haase and C Ochsenfeld and B V Lotsch},

url = {http://dx.doi.org/10.1039/D1SC04143F},

doi = {10.1039/D1SC04143F},

issn = {2041-6520},

year  = {2021},

date = {2021-11-15},

urldate = {2021-11-15},

journal = {Chemical Science},

volume = {12},

number = {45},

pages = {15143-15150},

abstract = {Covalent organic frameworks (COFs) offer a number of key properties that predestine them to be used as heterogeneous photocatalysts, including intrinsic porosity, long-range order, and light absorption. Since COFs can be constructed from a practically unlimited library of organic building blocks, these properties can be precisely tuned by choosing suitable linkers. Herein, we report the construction and use of a novel COF (FEAx-COF) photocatalyst, inspired by natural flavin cofactors. We show that the functionality of the alloxazine chromophore incorporated into the COF backbone is retained and study the effects of this heterogenization approach by comparison with similar molecular photocatalysts. We find that the integration of alloxazine chromophores into the framework significantly extends the absorption spectrum into the visible range, allowing for photocatalytic oxidation of benzylic alcohols to aldehydes even with low-energy visible light. In addition, the activity of the heterogeneous COF photocatalyst is less dependent on the chosen solvent, making it more versatile compared to molecular alloxazines. Finally, the use of oxygen as the terminal oxidant renders FEAx-COF a promising and “green” heterogeneous photocatalyst.},

keywords = {Foundry Organic, Molecularly-Functionalized},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Modular Assembly of Vibrationally and Electronically Coupled Rhenium Bipyridine Carbonyl Complexes on Silicon},

author = {J D Bartl and C Thomas and A Henning and M F Ober and G Savasci and B Yazdanshenas and P S Deimel and E Magnano and F Bondino and P Zeller and L Gregoratti and M Amati and C Paulus and F Allegretti and A Cattani-Scholz and J V Barth and C Ochsenfeld and B Nickel and I D Sharp and M Stutzmann and B Rieger},

url = {https://doi.org/10.1021/jacs.1c09061},

doi = {10.1021/jacs.1c09061},

issn = {0002-7863},

year  = {2021},

date = {2021-11-12},

urldate = {2021-11-12},

journal = {Journal of the American Chemical Society},

volume = {143},

pages = {19505},

abstract = {Hybrid inorganic/organic heterointerfaces are promising systems for next-generation photocatalytic, photovoltaic, and chemical-sensing applications. Their performance relies strongly on the development of robust and reliable surface passivation and functionalization protocols with (sub)molecular control. The structure, stability, and chemistry of the semiconductor surface determine the functionality of the hybrid assembly. Generally, these modification schemes have to be laboriously developed to satisfy the specific chemical demands of the semiconductor surface. The implementation of a chemically independent, yet highly selective, standardized surface functionalization scheme, compatible with nanoelectronic device fabrication, is of utmost technological relevance. Here, we introduce a modular surface assembly (MSA) approach that allows the covalent anchoring of molecular transition-metal complexes with sub-nanometer precision on any solid material by combining atomic layer deposition (ALD) and selectively self-assembled monolayers of phosphonic acids. ALD, as an essential tool in semiconductor device fabrication, is used to grow conformal aluminum oxide activation coatings, down to sub-nanometer thicknesses, on silicon surfaces to enable a selective step-by-step layer assembly of rhenium(I) bipyridine tricarbonyl molecular complexes. The modular surface assembly of molecular complexes generates precisely structured spatial ensembles with strong intermolecular vibrational and electronic coupling, as demonstrated by infrared spectroscopy, photoluminescence, and X-ray photoelectron spectroscopy analysis. The structure of the MSA can be chosen to avoid electronic interactions with the semiconductor substrate to exclusively investigate the electronic interactions between the surface-immobilized molecular complexes.},

keywords = {Foundry Inorganic, Foundry Organic, Molecularly-Functionalized, Solid-Solid},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {How Blinking Affects Photon Correlations in Multichromophoric Nanoparticles},

author = {T Schr\"{o}der and S Bange and J Schedlbauer and F Steiner and J M Lupton and P Tinnefeld and J Vogelsang},

url = {https://doi.org/10.1021/acsnano.1c06649},

doi = {10.1021/acsnano.1c06649},

issn = {1936-0851},

year  = {2021},

date = {2021-11-04},

urldate = {2021-11-04},

journal = {ACS Nano},

abstract = {A single chromophore can only emit a maximum of one single photon per excitation cycle. This limitation results in a phenomenon commonly referred to as photon antibunching (pAB). When multiple chromophores contribute to the fluorescence measured, the degree of pAB has been used as a metric to “count” the number of chromophores. But the fact that chromophores can switch randomly between bright and dark states also impacts pAB and can lead to incorrect chromophore numbers being determined from pAB measurements. By both simulations and experiment, we demonstrate how pAB is affected by independent and collective chromophore blinking, enabling us to formulate universal guidelines for correct interpretation of pAB measurements. We use DNA-origami nanostructures to design multichromophoric model systems that exhibit either independent or collective chromophore blinking. Two approaches are presented that can distinguish experimentally between these two blinking mechanisms. The first one utilizes the different excitation intensity dependence on the blinking mechanisms. The second approach exploits the fact that collective blinking implies energy transfer to a quenching moiety, which is a time-dependent process. In pulsed-excitation experiments, the degree of collective blinking can therefore be altered by time gating the fluorescence photon stream, enabling us to extract the energy-transfer rate to a quencher. The ability to distinguish between different blinking mechanisms is valuable in materials science, such as for multichromophoric nanoparticles like conjugated-polymer chains as well as in biophysics, for example, for quantitative analysis of protein assemblies by counting chromophores.},

keywords = {Foundry Organic, Molecularly-Functionalized},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Scalable Fabrication of Metallic Nanogaps at the Sub-10 nm Level},

author = {S Luo and B H Hoff and S A Maier and J C De Mello},

doi = {10.1002/advs.202102756},

issn = {2198-3844},

year  = {2021},

date = {2021-10-31},

journal = {Adv Sci (Weinh)},

pages = {e2102756},

abstract = {Metallic nanogaps with metal-metal separations of less than 10 nm have many applications in nanoscale photonics and electronics. However, their fabrication remains a considerable challenge, especially for applications that require patterning of nanoscale features over macroscopic length-scales. Here, some of the most promising techniques for nanogap fabrication are evaluated, covering established technologies such as photolithography, electron-beam lithography (EBL), and focused ion beam (FIB) milling, plus a number of newer methods that use novel electrochemical and mechanical means to effect the patterning. The physical principles behind each method are reviewed and their strengths and limitations for nanogap patterning in terms of resolution, fidelity, speed, ease of implementation, versatility, and scalability to large substrate sizes are discussed.},

keywords = {Molecularly-Functionalized},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Biopolymer-Templated Deposition of Ordered and Polymorph Titanium Dioxide Thin Films for Improved Surface-Enhanced Raman Scattering Sensitivity},

author = {Q Chen and M Betker and C Harder and C J Brett and M Schwartzkopf and N M Ulrich and M E Toimil-Molares and C Trautmann and L D S\"{o}derberg and C L Weindl and V K\"{o}rstgens and P M\"{u}ller-Buschbaum and M Ma and S V Roth},

url = {https://onlinelibrary.wiley.com/doi/abs/10.1002/adfm.202108556},

doi = {https://doi.org/10.1002/adfm.202108556},

issn = {1616-301X},

year  = {2021},

date = {2021-10-27},

journal = {Adv. Funct. Mater.},

volume = {n/a},

number = {n/a},

pages = {2108556},

abstract = {Abstract Titanium dioxide (TiO2) is an excellent candidate material for semiconductor metal oxide-based substrates for surface-enhanced Raman scattering (SERS). Biotemplated fabrication of TiO2 thin films with a 3D network is a promising route for effectively transferring the morphology and ordering of the template into the TiO2 layer. The control over the crystallinity of TiO2 remains a challenge due to the low thermal stability of biopolymers. Here is reported a novel strategy of the cellulose nanofibril (CNF)-directed assembly of TiO2/CNF thin films with tailored morphology and crystallinity as SERS substrates. Polymorphous TiO2/CNF thin films with well-defined morphology are obtained by combining atomic layer deposition and thermal annealing. A high enhancement factor of 1.79 × 106 in terms of semiconductor metal oxide nanomaterial (SMON)-based SERS substrates is obtained from the annealed TiO2/CNF thin films with a TiO2 layer thickness of 10 nm fabricated on indium tin oxide (ITO), when probed by 4-mercaptobenzoic acid molecules. Common SERS probes down to 10 nm can be detected on these TiO2/CNF substrates, indicating superior sensitivity of TiO2/CNF thin films among SMON SERS substrates. This improvement in SERS sensitivity is realized through a cooperative modulation of the template morphology of the CNF network and the crystalline state of TiO2.},

keywords = {Foundry Inorganic, Molecularly-Functionalized},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Tip Coupling and Array Effects of Gold Nanoantennas in Near-Field Microscopy},

author = {R B\"{u}chner and T Weber and L K\"{u}hner and S A Maier and A Tittl},

url = {https://doi.org/10.1021/acsphotonics.1c00744},

doi = {10.1021/acsphotonics.1c00744},

year  = {2021},

date = {2021-10-14},

journal = {ACS Photonics},

abstract = {Scattering-type scanning near-field optical microscopy (s-SNOM) is one of the predominant techniques for the nanoscale characterization of optical properties. The optical response of nanoantennas in s-SNOM is highly sensitive to their environment, including influences of the probing tip or neighboring resonators. Dielectric tips are commonly employed to minimize tip-related perturbations, although they provide a comparatively weak scattering signal. Here we show that when using metallic tips, it is possible to select between distinct weak and strong tip\textendashantenna coupling regimes by careful tailoring of the illumination conditions and resonator orientation. This enables the use of highly scattering metallic instead of dielectric tips for mapping plasmonic modes with comparatively higher signal strengths. This is a particular advantage for the retrieval of near-field spectra, which simultaneously require high near-field signals and unperturbed field patterns. We leverage our approach to analyze the collective effects of nanoantenna arrays, phenomena that are well understood in the optical far-field but have not been extensively studied in the near-field. Probing the dependence of the optical response on the array field size, we identify three regimes: the single rod regime, the intermediate regime, and the array-like regime. We show that these array effects give rise to characteristic spectral features originating from a complex interplay of radiative coupling and plasmon hybridization. These results provide evidence that long-range interactions of antennas also influence the local optical response that is probed in s-SNOM and demonstrate how collective resonances emerge from single building blocks, providing guidelines for optimized array designs for near- and far-field applications.},

keywords = {Molecularly-Functionalized},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Targetable Conformationally Restricted Cyanines Enable Photon-Count-Limited Applications**},

author = {P Eiring and R Mclaughlin and S S Matikonda and Z Han and L Grabenhorst and D A Helmerich and M Meub and G Beliu and M Luciano and V Bandi and N Zijlstra and Z-D Shi and S G Tarasov and R Swenson and P Tinnefeld and V Glembockyte and T Cordes and M Sauer and M J Schnermann},

url = {https://onlinelibrary.wiley.com/doi/abs/10.1002/anie.202109749},

doi = {https://doi.org/10.1002/anie.202109749},

issn = {1433-7851},

year  = {2021},

date = {2021-10-04},

urldate = {2021-10-04},

journal = {Angewandte Chemie International Edition},

volume = {60},

number = {51},

pages = {26685-26693},

abstract = {Abstract Cyanine dyes are exceptionally useful probes for a range of fluorescence-based applications, but their photon output can be limited by trans-to-cis photoisomerization. We recently demonstrated that appending a ring system to the pentamethine cyanine ring system improves the quantum yield and extends the fluorescence lifetime. Here, we report an optimized synthesis of persulfonated variants that enable efficient labeling of nucleic acids and proteins. We demonstrate that a bifunctional sulfonated tertiary amide significantly improves the optical properties of the resulting bioconjugates. These new conformationally restricted cyanines are compared to the parent cyanine derivatives in a range of contexts. These include their use in the plasmonic hotspot of a DNA-nanoantenna, in single-molecule F\"{o}rster-resonance energy transfer (FRET) applications, far-red fluorescence-lifetime imaging microscopy (FLIM), and single-molecule localization microscopy (SMLM). These efforts define contexts in which eliminating cyanine isomerization provides meaningful benefits to imaging performance.},

keywords = {Foundry Inorganic, Foundry Organic, Molecularly-Functionalized},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Conductivity mechanism in ionic 2D carbon nitrides: from hydrated ion motion to enhanced photocatalysis},

author = {J Kr\"{o}ger and F Podjaski and G Sava\c{s}\c{c}ı and I Moudrakovski and A Jimenez-Solano and M W Terban and S Bette and V Duppel and M Joos and A Senocrate},

year  = {2021},

date = {2021-09-12},

journal = {Cambridge University Press},

keywords = {Foundry Inorganic, Molecularly-Functionalized},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Interlayer Interactions as Design Tool for Large-Pore COFs},

author = {S T Emmerling and R Schuldt and S Bette and L Yao and R E Dinnebier and J K\"{a}stner and B V Lotsch},

url = {https://doi.org/10.1021/jacs.1c06518},

doi = {10.1021/jacs.1c06518},

issn = {0002-7863},

year  = {2021},

date = {2021-09-08},

urldate = {2021-09-08},

journal = {Journal of the American Chemical Society},

volume = {143},

number = {38},

pages = {15711-15722},

abstract = {Covalent organic frameworks (COFs) with a pore size beyond 5 nm are still rarely seen in this emerging field. Besides obvious complications such as the elaborated synthesis of large linkers with sufficient solubility, more subtle challenges regarding large-pore COF synthesis, including pore occlusion and collapse, prevail. Here we present two isoreticular series of large-pore imine COFs with pore sizes up to 5.8 nm and correlate the interlayer interactions with the structure and thermal behavior of the COFs. By adjusting interlayer interactions through the incorporation of methoxy groups acting as pore-directing “anchors”, different stacking modes can be accessed, resulting in modified stacking polytypes and, hence, effective pore sizes. A strong correlation between stacking energy toward highly ordered, nearly eclipsed structures, higher structural integrity during thermal stress, and a novel, thermally induced phase transition of stacking modes in COFs was found, which sheds light on viable design strategies for increased structural control and stability in large-pore COFs.},

keywords = {Foundry Organic, Molecularly-Functionalized},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Surface-Mediated Ring-Opening and Porphyrin Deconstruction via Conformational Distortion},

author = {F Bischoff and A Riss and G S Michelitsch and J Ducke and J V Barth and K Reuter and W Auw\"{a}rter},

url = {https://doi.org/10.1021/jacs.1c05348},

doi = {10.1021/jacs.1c05348},

issn = {0002-7863},

year  = {2021},

date = {2021-09-02},

urldate = {2021-09-02},

journal = {Journal of the American Chemical Society},

volume = {143},

number = {37},

pages = {15131-15138},

abstract = {The breakdown of macrocyclic compounds is of utmost importance in manifold biological and chemical processes, usually proceeding via oxygenation-induced ring-opening reactions. Here, we introduce a surface chemical route to selectively break a prototypical porphyrin species, cleaving off one pyrrole unit and affording a tripyrrin derivative. This pathway, operational in an ultrahigh vacuum environment at moderate temperature is enabled by a distinct molecular conformation achieved via the specific interaction between the porphyrin and its copper support. We provide an atomic-level characterization of the surface-anchored tripyrrin, its reaction intermediates, and byproducts by bond-resolved atomic force microscopy, unequivocally identifying the molecular skeletons. The ring-opening is rationalized by the distortion reducing the macrocycle’s stability. Our findings open a route to steer ring-opening reactions by conformational design and to study intriguing tetrapyrrole catabolite analogues on surfaces.},

keywords = {Molecularly-Functionalized},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Selective functionalization of the 1H-imidazo[1,2-b]pyrazole scaffold. A new potential non-classical isostere of indole and a precursor of push\textendashpull dyes},

author = {K Schw\"{a}rzer and S K Rout and D Bessinger and F Lima and C E Brocklehurst and K Karaghiosoff and T Bein and P Knochel},

url = {http://dx.doi.org/10.1039/D1SC04155J},

doi = {10.1039/D1SC04155J},

issn = {2041-6520},

year  = {2021},

date = {2021-08-30},

urldate = {2021-08-30},

journal = {Chemical Science},

volume = {12},

number = {39},

pages = {12993-13000},

abstract = {We report the selective functionalization of the 1H-imidazo[1,2-b]pyrazole scaffold using a Br/Mg-exchange, as well as regioselective magnesiations and zincations with TMP-bases (TMP = 2,2,6,6-tetramethylpiperidyl), followed by trapping reactions with various electrophiles. In addition, we report a fragmentation of the pyrazole ring, giving access to push\textendashpull dyes with a proaromatic (1,3-dihydro-2H-imidazol-2-ylidene)malononitrile core. These functionalization methods were used in the synthesis of an isostere of the indolyl drug pruvanserin. Comparative assays between the original drug and the isostere showed that a substitution of the indole ring with a 1H-imidazo[1,2-b]pyrazole results in a significantly improved solubility in aqueous media.},

keywords = {Foundry Organic, Molecularly-Functionalized},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {DNA Origami Nanoantennas for Fluorescence Enhancement},

author = {V Glembockyte and L Grabenhorst and K Trofymchuk and P Tinnefeld},

url = {https://doi.org/10.1021/acs.accounts.1c00307},

doi = {10.1021/acs.accounts.1c00307},

issn = {0001-4842},

year  = {2021},

date = {2021-08-26},

urldate = {2021-08-26},

journal = {Accounts of Chemical Research},

volume = {54},

number = {17},

pages = {3338-3348},

abstract = {ConspectusThe possibility to increase fluorescence by plasmonic effects in the near-field of metal nanostructures was recognized more than half a century ago. A major challenge, however, was to use this effect because placing single quantum emitters in the nanoscale plasmonic hotspot remained unsolved for a long time. This not only presents a chemical problem but also requires the nanostructure itself to be coaligned with the polarization of the excitation light. Additional difficulties arise from the complex distance dependence of fluorescence emission: in contrast to other surface-enhanced spectroscopies (such as Raman spectroscopy), the emitter should not be placed as close as possible to the metallic nanostructure but rather needs to be at an optimal distance on the order of a few nanometers to avoid undesired quenching effects.Our group addressed these challenges almost a decade ago by exploiting the unique positioning ability of DNA nanotechnology and reported the first self-assembled DNA origami nanoantennas. This Account summarizes our work spanning from this first proof-of-principle study to recent advances in utilizing DNA origami nanoantennas for single DNA molecule detection on a portable smartphone microscope.We summarize different aspects of DNA origami nanoantennas that are essential for achieving strong fluorescence enhancement and discuss how single-molecule fluorescence studies helped us to gain a better understanding of the interplay between fluorophores and plasmonic hotspots. Practical aspects of preparing the DNA origami nanoantennas and extending their utility are also discussed.Fluorescence enhancement in DNA origami nanoantennas is especially exciting for signal amplification in molecular diagnostic assays or in single-molecule biophysics, which could strongly benefit from higher time resolution. Additionally, biophysics can greatly profit from the ultrasmall effective detection volumes provided by DNA nanoantennas that allow single-molecule detection at drastically elevated concentrations as is required, e.g., in single-molecule DNA sequencing approaches.Finally, we describe our most recent progress in developing DNA NanoAntennas with Cleared HOtSpots (NACHOS) that are fully compatible with biomolecular assays. The developed DNA origami nanoantennas have proven robustness and remain functional after months of storage. As an example, we demonstrated for the first time the single-molecule detection of DNA specific to antibiotic-resistant bacteria on a portable and battery-driven smartphone microscope enabled by DNA origami nanoantennas. These recent developments mark a perfect moment to summarize the principles and the synthesis of DNA origami nanoantennas and give an outlook of new exciting directions toward using different nanomaterials for the construction of nanoantennas as well as for their emerging applications.},

keywords = {Foundry Inorganic, Foundry Organic, Molecularly-Functionalized},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Morphology Transformation Pathway of Block Copolymer-Directed Cooperative Self-Assembly of ZnO Hybrid Films Monitored In Situ during Slot-Die Coating},

author = {T Tian and S Yin and S Tu and C L Weindl and K S Wienhold and S Liang and M Schwartzkopf and S V Roth and P M\"{u}ller-Buschbaum},

url = {https://onlinelibrary.wiley.com/doi/abs/10.1002/adfm.202105644},

doi = {https://doi.org/10.1002/adfm.202105644},

issn = {1616-301X},

year  = {2021},

date = {2021-08-12},

journal = {Advanced Functional Materials},

volume = {n/a},

number = {n/a},

pages = {2105644},

abstract = {Abstract Cooperative self-assembly (co-assembly) of diblock copolymers (DBCs) and inorganic precursors that takes inspiration from the rich phase separation behavior of DBCs can enable the realization of a broad spectrum of functional nanostructures with the desired sizes. In a DBC assisted sol\textendashgel chemistry approach with polystyrene-block-poly(ethylene oxide) and ZnO, hybrid films are formed with slot-die coating. Pure DBC films are printed as control. In situ grazing-incidence small-angle X-ray scattering measurements are performed to investigate the self-assembly and co-assembly process during the film formation. Combining complementary ex situ characterizations, several distinct regimes are differentiated to describe the morphological transformations from the initially solvent-dispersed to the ultimately solidified films. The comparison of the assembly pathway evidences that the key step in the establishment of the pure DBC film is the coalescence of spherical micelles toward cylindrical domains. Due to the presence of the phase-selective precursor, the formation of cylindrical aggregates in the solution is crucial for the structural development of the hybrid film. The pre-existing cylinders in the ink impede the domain growth of the hybrid film during the subsequent drying process. The precursor reduces the degree of order, prevents crystallization of the PEO block, and introduces additional length scales in the hybrid films.},

keywords = {Foundry Inorganic, Molecularly-Functionalized},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {Interfacial Synthesis of Layer-Oriented 2D Conjugated Metal\textendashOrganic Framework Films toward Directional Charge Transport},

author = {Z Wang and L S Walter and M Wang and P S Petkov and B Liang and H Qi and N N Nguyen and M Hambsch and H Zhong and M Wang and S Park and L Renn and K Watanabe and T Taniguchi and S C B Mannsfeld and T Heine and U Kaiser and S Zhou and R T Weitz and X Feng and R Dong},

url = {https://doi.org/10.1021/jacs.1c05051},

doi = {10.1021/jacs.1c05051},

issn = {0002-7863},

year  = {2021},

date = {2021-08-03},

journal = {Journal of the American Chemical Society},

abstract = {The development of layer-oriented two-dimensional conjugated metal\textendashorganic frameworks (2D c-MOFs) enables access to direct charge transport, dial-in lateral/vertical electronic devices, and the unveiling of transport mechanisms but remains a significant synthetic challenge. Here we report the novel synthesis of metal-phthalocyanine-based p-type semiconducting 2D c-MOF films (Cu2[PcM\textendashO8]},

keywords = {Molecularly-Functionalized},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Advanced Printed Semiconductors for Energy and Electronic Applications},

author = {T Ameri and L Ke and N Gasparini and R Soltani and M G\"{u}nther and A Buyruk and A A Amin},

url = {https://www.proceedings.iaamonline.org/image/article/1628028399Tayebeh-Ameri---Abstract.pdf},

doi = {https://www.proceedings.iaamonline.org/image/article/1628028399Tayebeh-Ameri---Abstract.pdf},

year  = {2021},

date = {2021-08-03},

urldate = {2021-08-03},

journal = {Video Proceedings of Advanced Materials},

volume = {2},

keywords = {Foundry Organic, Molecularly-Functionalized},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {Metamorphosis of Heterostructured Surface-Mounted Metal\textendashOrganic Frameworks Yielding Record Oxygen Evolution Mass Activities},

author = {S Hou and W Li and S Watzele and R M Kluge and S Xue and S Yin and X Jiang and M D\"{o}blinger and A Welle and B Garlyyev and M Koch and P M\"{u}ller-Buschbaum and C W\"{o}ll and A S Bandarenka and R A Fischer},

url = {https://onlinelibrary.wiley.com/doi/abs/10.1002/adma.202103218},

doi = {https://doi.org/10.1002/adma.202103218},

issn = {0935-9648},

year  = {2021},

date = {2021-08-01},

urldate = {2021-08-01},

journal = {Advanced Materials},

volume = {33},

pages = {2103218},

abstract = {Abstract Materials derived from surface-mounted metal\textendashorganic frameworks (SURMOFs) are promising electrocatalysts for the oxygen evolution reaction (OER). A series of mixed-metal, heterostructured SURMOFs is fabricated by the facile layer-by-layer deposition method. The obtained materials reveal record-high electrocatalyst mass activities of ≈2.90 kA g−1 at an overpotential of 300 mV in 0.1 m KOH, superior to the benchmarking precious and nonprecious metal electrocatalysts. This property is assigned to the particular in situ self-reconstruction and self-activation of the SURMOFs during the immersion and the electrochemical treatment in alkaline aqueous electrolytes, which allows for the generation of NiFe (oxy)hydroxide electrocatalyst materials of specific morphology and microstructure.},

keywords = {Foundry Inorganic, Molecularly-Functionalized},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {H2 Evolution from Electrocatalysts with Redox-Active Ligands: Mechanistic Insights from Theory and Experiment vis-\`{a}-vis Co-Mabiq},

author = {G C Tok and S Reiter and A T S Freiberg and L Reinschl\"{u}ssel and H A Gasteiger and R De Vivie-Riedle and C R Hess},

url = {https://doi.org/10.1021/acs.inorgchem.1c01157},

doi = {10.1021/acs.inorgchem.1c01157},

issn = {0020-1669},

year  = {2021},

date = {2021-07-23},

urldate = {2021-07-23},

journal = {Inorganic Chemistry},

abstract = {Electrocatalytic hydrogen production via transition metal complexes offers a promising approach for chemical energy storage. Optimal platforms to effectively control the proton and electron transfer steps en route to H2 evolution still need to be established, and redox-active ligands could play an important role in this context. In this study, we explore the role of the redox-active Mabiq (Mabiq = 2\textendash4:6\textendash8-bis(3,3,4,4-tetramethlyldihydropyrrolo)-10\textendash15-(2,2-biquinazolino)-[15]-1,3,5,8,10,14-hexaene1,3,7,9,11,14-N6) ligand in the hydrogen evolution reaction (HER). Using spectro-electrochemical studies in conjunction with quantum chemical calculations, we identified two precatalytic intermediates formed upon the addition of two electrons and one proton to [CoII(Mabiq)(THF)](PF6) (CoMbq). We further examined the acid strength effect on the generation of the intermediates. The generation of the first intermediate, CoMbq-H1, involves proton addition to the bridging imine-nitrogen atom of the ligand and requires strong proton activity. The second intermediate, CoMbq-H2, acquires a proton at the diketiminate carbon for which a weaker proton activity is sufficient. We propose two decoupled H2 evolution pathways based on these two intermediates, which operate at different overpotentials. Our results show how the various protonation sites of the redox-active Mabiq ligand affect the energies and activities of HER intermediates.},

keywords = {Foundry Inorganic, Molecularly-Functionalized},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {Fermi Level Equilibration at the Metal\textendashMolecule Interface in Plasmonic Systems},

author = {A Stefancu and S Lee and L Zhu and M Liu and R C Lucacel and E Cort\'{e}s and N Leopold},

url = {https://doi.org/10.1021/acs.nanolett.1c02003},

doi = {10.1021/acs.nanolett.1c02003},

issn = {1530-6984},

year  = {2021},

date = {2021-07-22},

urldate = {2021-07-22},

journal = {Nano Letters},

abstract = {We highlight a new metal\textendashmolecule charge transfer process by tuning the Fermi energy of plasmonic silver nanoparticles (AgNPs) in situ. The strong adsorption of halide ions upshifts the Fermi level of AgNPs by up to ∼0.3 eV in the order Cl\textendash < Br\textendash < I\textendash, favoring the spontaneous charge transfer to aligned molecular acceptor orbitals until charge neutrality across the interface is achieved. By carefully quantifying, experimentally and theoretically, the Fermi level upshift, we show for the first time that this effect is comparable in energy to different plasmonic effects such as the plasmoelectric effect or hot-carriers production. Moreover, by monitoring in situ the adsorption dynamic of halide ions in different AgNP\textendashmolecule systems, we show for the first time that the catalytic role of halide ions in plasmonic nanostructures depends on the surface affinity of halide ions compared to that of the target molecule.},

keywords = {Foundry Inorganic, Molecularly-Functionalized},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {Cluster Catalysis with Lattice Oxygen: Tracing Oxygen Transport from a Magnetite (001) Support onto Small Pt Clusters},

author = {S Kaiser and F Maleki and K Zhang and W Harbich and U Heiz and S Tosoni and B A J Lechner and G Pacchioni and F Esch},

url = {https://pubs.acs.org/doi/10.1021/acscatal.1c01451},

year  = {2021},

date = {2021-07-16},

urldate = {2021-07-16},

journal = {ACS Catalysis},

volume = {11},

number = {15},

pages = {9519\textendash9529},

keywords = {Foundry Inorganic, Molecularly-Functionalized, Solid-Solid},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {Band gap engineering in blended organic semiconductor films based on dielectric interactions},

author = {K Ortstein and S Hutsch and M Hambsch and K Tvingstedt and B Wegner and J Benduhn and J Kublitski and M Schwarze and S Schellhammer and F Talnack and A Vogt and P B\"{a}uerle and N Koch and S C B Mannsfeld and H Kleemann and F Ortmann and K Leo},

url = {https://doi.org/10.1038/s41563-021-01025-z},

doi = {10.1038/s41563-021-01025-z},

issn = {1476-4660},

year  = {2021},

date = {2021-06-10},

urldate = {2021-06-10},

journal = {Nature Materials},

abstract = {Blending organic molecules to tune their energy levels is currently being investigated as an approach to engineer the bulk and interfacial optoelectronic properties of organic semiconductors. It has been proven that the ionization energy and electron affinity can be equally shifted in the same direction by electrostatic effects controlled by blending similar halogenated derivatives with different energetics. Here we show that the energy gap of organic semiconductors can also be tuned by blending. We use oligothiophenes with different numbers of thiophene rings as an example and investigate their structure and electronic properties. Photoelectron spectroscopy and inverse photoelectron spectroscopy show tunability of the single-particle gap, with the optical gaps showing similar, but smaller, effects. Theoretical analysis shows that this tuning is mainly caused by a change in the dielectric constant with blend ratio. Further studies will explore the practical impact of this energy-level engineering strategy for optoelectronic devices.},

keywords = {Foundry Organic, Molecularly-Functionalized},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {In situ monitoring of mechanochemical covalent organic framework formation reveals templating effect of liquid additive},

author = {S T Emmerling and L S Germann and P A Julien and I Moudrakovski and M Etter and T Fri\v{s}\v{c}i\'{c} and R E Dinnebier and B V Lotsch},

url = {https://www.sciencedirect.com/science/article/pii/S2451929421002138},

doi = {https://doi.org/10.1016/j.chempr.2021.04.012},

issn = {2451-9294},

year  = {2021},

date = {2021-06-10},

journal = {Chem},

volume = {7},

number = {6},

pages = {1639-1652},

abstract = {Summary Covalent organic frameworks (COFs) have emerged as a new class of molecularly precise, porous functional materials characterized by broad structural and chemical versatility, with a diverse range of applications. Despite their increasing popularity, fundamental aspects of COF formation are poorly understood, lacking profound experimental insights into their assembly. Here, we use a combination of in situ X-ray powder diffraction and Raman spectroscopy to elucidate the reaction mechanism of mechanochemical synthesis of imine COFs, leading to the observation of key reaction intermediates that offer direct experimental evidence of framework templating through liquid additives. Moreover, the solid-state catalyst scandium triflate is instrumental in directing the reaction kinetics and mechanism, yielding COFs with crystallinity and porosity on par with solvothermal products. This work provides the first experimental evidence of solvent-based COF templating and is a significant advancement in mechanistic understanding of mechanochemistry as a green route for COF synthesis.},

keywords = {Foundry Organic, Molecularly-Functionalized},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Nanocellulose-Assisted Thermally Induced Growth of Silver Nanoparticles for Optical Applications},

author = {C J Brett and W Ohm and B Fricke and A E Alexakis and T Laarmann and V K\"{o}rstgens and P M\"{u}ller-Buschbaum and L D S\"{o}derberg and S V Roth},

url = {https://doi.org/10.1021/acsami.1c07544},

doi = {10.1021/acsami.1c07544},

issn = {1944-8244},

year  = {2021},

date = {2021-06-07},

journal = {ACS Applied Materials \& Interfaces},

volume = {13},

number = {23},

pages = {27696-27704},

abstract = {Optically responsive materials are present in everyday life, from screens to sensors. However, fabricating large-area, fossil-free materials for functional biocompatible applications is still a challenge today. Nanocelluloses from various sources, such as wood, can provide biocompatibility and are emerging candidates for templating organic optoelectronics. Silver (Ag) in its nanoscale form shows excellent optical properties. Herein, we combine both materials using thin-film large-area spray-coating to study the fabrication of optical response applications. We characterize the Ag nanoparticle formation by X-ray scattering and UV\textendashvis spectroscopy in situ during growth on the nanocellulose template. The morphology and optical properties of the nanocellulose film are compared to the rigid reference surface SiO2. Our results clearly show the potential to tailor the energy band gap of the resulting hybrid material.},

keywords = {Foundry Inorganic, Molecularly-Functionalized},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Understanding disorder and linker deficiency in porphyrinic zirconium-based metal\textendashorganic frameworks by resolving the Zr8O6 cluster conundrum in PCN-221},

author = {C Koschnick and R St\"{a}glich and T Scholz and M W Terban and A Von Mankowski and G Savasci and F Binder and A Sch\"{o}kel and M Etter and J Nuss and R Siegel and L S Germann and C Ochsenfeld and R E Dinnebier and J Senker and B V Lotsch},

url = {https://doi.org/10.1038/s41467-021-23348-w},

doi = {10.1038/s41467-021-23348-w},

issn = {2041-1723},

year  = {2021},

date = {2021-05-25},

journal = {Nature Communications},

volume = {12},

number = {1},

pages = {3099},

abstract = {Porphyrin-based metal\textendashorganic frameworks (MOFs), exemplified by MOF-525, PCN-221, and PCN-224, are promising systems for catalysis, optoelectronics, and solar energy conversion. However, subtle differences between synthetic protocols for these three MOFs give rise to vast discrepancies in purported product outcomes and description of framework topologies. Here, based on a comprehensive synthetic and structural analysis spanning local and long-range length scales, we show that PCN-221 consists of Zr6O4(OH)4 clusters in four distinct orientations within the unit cell, rather than Zr8O6 clusters as originally published, and linker vacancies at levels of around 50%, which may form in a locally correlated manner. We propose disordered PCN-224 (dPCN-224) as a unified model to understand PCN-221, MOF-525, and PCN-224 by varying the degree of orientational cluster disorder, linker conformation and vacancies, and cluster\textendashlinker binding. Our work thus introduces a new perspective on network topology and disorder in Zr-MOFs and pinpoints the structural variables that direct their functional properties.},

keywords = {Foundry Inorganic, Molecularly-Functionalized},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Selective area growth of GaN nanowires and nanofins by molecular beam epitaxy on heteroepitaxial diamond (001) substrates},

author = {F Pantle and F Becker and M Kraut and S W\"{o}rle and T Hoffmann and S Artmeier and M Stutzmann},

url = {http://dx.doi.org/10.1039/D1NA00221J},

doi = {10.1039/D1NA00221J},

year  = {2021},

date = {2021-05-05},

journal = {Nanoscale Advances},

volume = {3},

number = {13},

pages = {3835-3845},

abstract = {GaN-on-diamond is a promising route towards reliable high-power transistor devices with outstanding performances due to better heat management, replacing common GaN-on-SiC technologies. Nevertheless, the implementation of GaN-on-diamond remains challenging. In this work, the selective area growth of GaN nanostructures on cost-efficient, large-scale available heteroepitaxial diamond (001) substrates by means of plasma-assisted molecular beam epitaxy is investigated. Additionally, we discuss the influence of an AlN buffer on the morphology of the GaN nanostructures. The nanowires and nanofins are characterized by a very high selectivity and controllable dimensions. Low temperature photoluminescence measurements are used to evaluate their structural quality. The growth of two GaN crystal domains, which are in-plane rotated against each other by 30°, is observed. The favoring of a certain domain is determined by the off-cut direction of the diamond substrates. By X-ray diffraction we show that the GaN nanostructures grow perpendicular to the diamond surface on off-cut diamond (001) substrates, which is in contrast to the growth on diamond (111), where the nanostructures are aligned with the substrate lattice. Polarity-selective wet chemical etching and Kelvin probe force microscopy reveal that the GaN nanostructures grow solely in the Ga-polar direction. This is a major advantage compared to the growth on diamond (111) and enables the application of GaN nanostructures on cost-efficient diamond for high-power/high-frequency applications.},

keywords = {Molecularly-Functionalized, Solid-Solid},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Massively Parallel Arrays of Size-Controlled Metallic Nanogaps with Gap-Widths Down to the Sub-3-nm Level},

author = {S Luo and A Mancini and R Bert\'{e} and B H Hoff and S A Maier and J C De Mello},

url = {https://onlinelibrary.wiley.com/doi/abs/10.1002/adma.202100491},

doi = {https://doi.org/10.1002/adma.202100491},

issn = {0935-9648},

year  = {2021},

date = {2021-05-03},

journal = {Advanced Materials},

volume = {33},

number = {20},

pages = {2100491},

abstract = {Abstract Metallic nanogaps (MNGs) are fundamental components of nanoscale photonic and electronic devices. However, the lack of reproducible, high-yield fabrication methods with nanometric control over the gap-size has hindered practical applications. A patterning technique based on molecular self-assembly and physical peeling is reported here that allows the gap-width to be tuned from more than 30 nm to less than 3 nm. The ability of the technique to define sub-3-nm gaps between dissimilar metals permits the easy fabrication of molecular rectifiers, in which conductive molecules bridge metals with differing work functions. A method is further described for fabricating massively parallel nanogap arrays containing hundreds of millions of ring-shaped nanogaps, in which nanometric size control is maintained over large patterning areas of up to a square centimeter. The arrays exhibit strong plasmonic resonances under visible light illumination and act as high-performance substrates for surface-enhanced Raman spectroscopy, with high enhancement factors of up to 3 × 108 relative to thin gold films. The methods described here extend the range of metallic nanostructures that can be fabricated over large areas, and are likely to find many applications in molecular electronics, plasmonics, and biosensing.},

keywords = {Foundry Inorganic, Molecularly-Functionalized},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {The central role of the metal ion for photoactivity: Zn\textendash vs. Ni\textendashMabiq},

author = {R Lauenstein and S L Mader and H Derondeau and O Z Esezobor and M Block and A J R\"{o}mer and C Jandl and E Riedle and V R I Kaila and J Hauer and E Thyrhaug and C R Hess},

url = {http://dx.doi.org/10.1039/D0SC06096H},

doi = {10.1039/D0SC06096H},

issn = {2041-6520},

year  = {2021},

date = {2021-04-21},

journal = {Chemical Science},

abstract = {Photoredox catalysts are integral components of artificial photosystems, and have recently emerged as powerful tools for catalysing numerous organic reactions. However, the development of inexpensive and efficient earth-abundant photoredox catalysts remains a challenge. We here present the photochemical and photophysical properties of a Ni\textendashMabiq catalyst ([NiII(Mabiq)]OTf (1); Mabiq = 2-4:6-8-bis(3,3,4,4-tetramethyldihydropyrrolo)-10-15-(2,2-biquinazolino)-[15]-1,3,5,8,10,14-hexaene1,3,7,9,11,14-N6)\textemdashand of a Zn-containing analogue ([ZnII(Mabiq)OTf] (2))\textemdashusing steady state and time resolved optical spectroscopy, time-dependent density functional theory (TDDFT) calculations, and reactivity studies. The Ni and Zn complexes exhibit similar absorption spectra, but markedly different photochemical properties. These differences arise because the excited states of 2 are ligand-localized, whereas metal-centered states account for the photoactivity of 1. The distinct properties of the Ni and Zn complexes are manifest in their behavior in the photo-driven aza-Henry reaction and oxidative coupling of methoxybenzylamine.},

keywords = {Molecularly-Functionalized, Solid-Liquid},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {Increasing Photostability of Inverted Nonfullerene Organic Solar Cells by Using Fullerene Derivative Additives},

author = {M G\"{u}nther and D Bl\"{a}tte and A L Oechsle and S S Rivas and Yousefi A A Amin and P M\"{u}ller-Buschbaum and T Bein and T Ameri},

url = {https://doi.org/10.1021/acsami.1c00700},

doi = {10.1021/acsami.1c00700},

issn = {1944-8244},

year  = {2021},

date = {2021-04-16},

urldate = {2021-04-16},

journal = {ACS Applied Materials \& Interfaces},

abstract = {Organic solar cells (OSCs) recently achieved efficiencies of over 18% and are well on their way to practical applications, but still considerable stability issues need to be overcome. One major problem emerges from the electron transport material zinc oxide (ZnO), which is mainly used in the inverted device architecture and decomposes many high-performance nonfullerene acceptors due to its photocatalytic activity. In this work, we add three different fullerene derivatives\textemdashPC71BM, ICMA, and BisPCBM\textemdashto an inverted binary PBDB-TF:IT-4F system in order to suppress the photocatalytic degradation of IT-4F on ZnO via the radical scavenging abilities of the fullerenes. We demonstrate that the addition of 5% fullerene not only increases the performance of the binary PBDB-TF:IT-4F system but also significantly improves the device lifetime under UV illumination in an inert atmosphere. While the binary devices lose 20% of their initial efficiency after only 3 h, this time is increased fivefold for the most promising ternary devices with ICMA. We attribute this improvement to a reduced photocatalytic decomposition of IT-4F in the ternary system, which results in a decreased recombination. We propose that the added fullerenes protect the IT-4F by acting as a sacrificial reagent, thereby suppressing the trap state formation. Furthermore, we show that the protective effect of the most promising fullerene ICMA is transferable to two other binary systems PBDB-TF:BTP-4F and PTB7-Th:IT-4F. Importantly, this effect can also increase the air stability of PBDB-TF:IT-4F. This work demonstrates that the addition of fullerene derivatives is a transferable and straightforward strategy to improve the stability of OSCs.},

keywords = {Foundry Organic, Molecularly-Functionalized},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {Fast-Switching Vis\textendashIR Electrochromic Covalent Organic Frameworks},

author = {D Bessinger and K Muggli and M Beetz and F Auras and T Bein},

url = {https://doi.org/10.1021/jacs.0c12392},

doi = {10.1021/jacs.0c12392},

issn = {0002-7863},

year  = {2021},

date = {2021-03-16},

journal = {Journal of the American Chemical Society},

abstract = {Electrochromic coatings are promising for applications in smart windows or energy-efficient optical displays. However, classical inorganic electrochromic materials such as WO3 suffer from low coloration efficiency and slow switching speed. We have developed highly efficient and fast-switching electrochromic thin films based on fully organic, porous covalent organic frameworks (COFs). The low band gap COFs have strong vis\textendashNIR absorption bands in the neutral state, which shift significantly upon electrochemical oxidation. Fully reversible absorption changes by close to 3 OD can be triggered at low operating voltages and low charge per unit area. Our champion material reaches an electrochromic coloration efficiency of 858 cm2 C\textendash1 at 880 nm and retains >95% of its electrochromic response over 100 oxidation/reduction cycles. Furthermore, the electrochromic switching is extremely fast with response times below 0.4 s for the oxidation and around 0.2 s for the reduction, outperforming previous COFs by at least an order of magnitude and rendering these materials some of the fastest-switching frameworks to date. This combination of high coloration efficiency and very fast switching reveals intriguing opportunities for applications of porous organic electrochromic materials.},

keywords = {Foundry Organic, Molecularly-Functionalized},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {Picosecond time-resolved photon antibunching measures nanoscale exciton motion and the true number of chromophores},

author = {G J Hedley and T Schr\"{o}der and F Steiner and T Eder and F J Hofmann and S Bange and D Laux and S H\"{o}ger and P Tinnefeld and J M Lupton and J Vogelsang},

url = {https://doi.org/10.1038/s41467-021-21474-z},

doi = {10.1038/s41467-021-21474-z},

issn = {2041-1723},

year  = {2021},

date = {2021-02-26},

journal = {Nature Communications},

volume = {12},

number = {1},

pages = {1327},

abstract = {The particle-like nature of light becomes evident in the photon statistics of fluorescence from single quantum systems as photon antibunching. In multichromophoric systems, exciton diffusion and subsequent annihilation occurs. These processes also yield photon antibunching but cannot be interpreted reliably. Here we develop picosecond time-resolved antibunching to identify and decode such processes. We use this method to measure the true number of chromophores on well-defined multichromophoric DNA-origami structures, and precisely determine the distance-dependent rates of annihilation between excitons. Further, this allows us to measure exciton diffusion in mesoscopic H- and J-type conjugated-polymer aggregates. We distinguish between one-dimensional intra-chain and three-dimensional inter-chain exciton diffusion at different times after excitation and determine the disorder-dependent diffusion lengths. Our method provides a powerful lens through which excitons can be studied at the single-particle level, enabling the rational design of improved excitonic probes such as ultra-bright fluorescent nanoparticles and materials for optoelectronic devices.},

keywords = {Foundry Organic, Molecularly-Functionalized},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Amine-Linked Covalent Organic Frameworks as a Platform for Postsynthetic Structure Interconversion and Pore-Wall Modification},

author = {L Grunenberg and G Savasci and M W Terban and V Duppel and I Moudrakovski and M Etter and R E Dinnebier and C Ochsenfeld and B V Lotsch},

url = {https://doi.org/10.1021/jacs.0c12249},

doi = {10.1021/jacs.0c12249},

issn = {0002-7863},

year  = {2021},

date = {2021-02-24},

urldate = {2021-02-24},

journal = {Journal of the American Chemical Society},

volume = {143},

number = {9},

pages = {3430-3438},

abstract = {Covalent organic frameworks have emerged as a powerful synthetic platform for installing and interconverting dedicated molecular functions on a crystalline polymeric backbone with atomic precision. Here, we present a novel strategy to directly access amine-linked covalent organic frameworks, which serve as a scaffold enabling pore-wall modification and linkage-interconversion by new synthetic methods based on Leuckart\textendashWallach reduction with formic acid and ammonium formate. Frameworks connected entirely by secondary amine linkages, mixed amine/imine bonds, and partially formylated amine linkages are obtained in a single step from imine-linked frameworks or directly from corresponding linkers in a one-pot crystallization-reduction approach. The new, 2D amine-linked covalent organic frameworks, rPI-3-COF, rTTI-COF, and rPy1P-COF, are obtained with high crystallinity and large surface areas. Secondary amines, installed as reactive sites on the pore wall, enable further postsynthetic functionalization to access tailored covalent organic frameworks, with increased hydrolytic stability, as potential heterogeneous catalysts.},

keywords = {Foundry Organic, Molecularly-Functionalized},

pubstate = {published},

tppubtype = {article}

}