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@article{nokey,

title = {A Platform for the Development of Highly Red-Shifted Azobenzene-Based Optical Tools},

author = {K L\"{u}tzel and H Laqua and M B Sathian and B Nissl and J K Sz\'{a}nt\'{o} and C A Senser and G Savasci and L Allmendinger and B Kicin and V Ruf and D Kammerer and T Lohm\"{u}ller and K Karaghiosoff and A M Ali and U Storch and M M Y Schnitzler and C Ochsenfeld and D B Konrad},

url = {\<Go to ISI\>://WOS:001512840500001},

doi = {10.1002/anie.202501779},

year  = {2025},

date = {2025-06-04},

journal = {Angewandte Chemie-International Edition},

abstract = {Azobenzenes are versatile photoswitches that can be used to generate elaborate optical tools, including photopharmaceuticals. However, the targeted application-guided design of new photoswitches with specific properties remains challenging. We have developed synthetic protocols for derivatives of the dfdc (di-ortho-fluoro-di-ortho-chloro) azobenzene scaffold with chemical alterations in the para-/ortho-positions and performed an in-depth study into the effects of their structures on their photophysical properties with an emphasis on the n -\> pi* absorption band using NMR, UV-vis, and X-ray analysis. The data was used to establish and validate a computational approach that allows to compute realistic UV-vis spectra by combining TD-DFT excited-state calculations from 6000 thermally accessible structures generated through MD simulations while considering the high structural flexibility of ortho-substituted azobenzenes. We added 15 new visible light-operated photoswitches to the toolbox for the development of optical devices with relaxation rates across multiple orders of magnitude and identified several examples with stronger bathochromic shifts than the dfdc azobenzene lead structure. Our combined experimental and computational study forms the foundation for the advanced in silico design and synthesis of new highly red-shifted photoswitches. To showcase the potential of dfdc azobenzenes for the development of chemical tools, we synthesized dfdc-OptoBI-1 and demonstrated its biological activity as a red light-operated activator of TRPC6 channels in HEK293 cells.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {An embedding scheme for constraint-based orbital-optimized excitations in molecular and bulk environments},

author = {Y Lemke and J Kussmann and C Ochsenfeld},

url = {http://dx.doi.org/10.1039/D5CP00839E},

doi = {10.1039/D5CP00839E},

issn = {1463-9076},

year  = {2025},

date = {2025-05-29},

journal = {Physical Chemistry Chemical Physics},

abstract = {We recently presented a novel approach to variationally determine electronically excited states based on constrained density functional theory calculations. The constraint-based orbital-optimized excited state method (COOX) [Kussmann et al., J. Chem. Theory Comput., 2024, 20, 8461\textendash8473] allows the evaluation of arbitrary electronic excitations and has several advantages compared to other methods like ΔSCF. In this work, we present an embedding scheme for COOX where the constraint potential is drawn from a sub-system calculation. This approach enables the accurate evaluation of specific excited states within complex environments that are difficult to obtain with conventional methods. The validity and range of applicability of the presented method are investigated for first exemplary calculations.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Highly Accurate and Robust Constraint-Based Orbital-Optimized Core Excitations},

author = {Y Lemke and J Kussmann and C Ochsenfeld},

url = {https://doi.org/10.1021/acs.jpca.4c04139},

doi = {10.1021/acs.jpca.4c04139},

issn = {1089-5639},

year  = {2024},

date = {2024-11-14},

journal = {The Journal of Physical Chemistry A},

volume = {128},

number = {45},

pages = {9804-9818},

abstract = {We adapt our recently developed constraint-based orbital-optimized excited-state method (COOX) for the computation of core excitations. COOX is a constrained density functional theory (cDFT) approach based on excitation amplitudes from linear-response time-dependent DFT (LR-TDDFT), and has been shown to provide accurate excitation energies and excited-state properties for valence excitations within a spin-restricted formalism. To extend COOX to core-excited states, we introduce a spin-unrestricted variant which allows us to obtain orbital-optimized core excitations with a single constraint. Using a triplet purification scheme in combination with the constrained unrestricted Hartree\textendashFock formalism, scalar-relativistic zero-order regular approximation corrections, and a semiempirical treatment of spin\textendashorbit coupling, COOX is shown to produce highly accurate results for K- and L-edge excitations of second- and third-period atoms with subelectronvolt errors despite being based on LR-TDDFT, for which core excitations pose a well-known challenge. L- and M-edge excitations of heavier atoms up to uranium are also computationally feasible and numerically stable, but may require more advanced treatment of relativistic effects. Furthermore, COOX is shown to perform on par with or better than the popular ΔSCF approach while exhibiting more robust convergence, highlighting it as a promising tool for inexpensive and accurate simulations of X-ray absorption spectra.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {A Constraint-Based Orbital-Optimized Excited State Method (COOX)},

author = {J Kussmann and Y Lemke and A Weinbrenner and C Ochsenfeld},

url = {https://doi.org/10.1021/acs.jctc.4c00467},

doi = {10.1021/acs.jctc.4c00467},

issn = {1549-9618},

year  = {2024},

date = {2024-10-08},

journal = {Journal of Chemical Theory and Computation},

volume = {20},

number = {19},

pages = {8461-8473},

abstract = {In this work, we present a novel method to directly calculate targeted electronic excited states within a self-consistent field calculation based on constrained density functional theory (cDFT). The constraint is constructed from the static occupied-occupied and virtual-virtual parts of the excited state difference density from (simplified) linear-response time-dependent density functional theory calculations (LR-TDDFT). Our new method shows a stable convergence behavior, provides an accurate excited state density adhering to the Aufbau principle, and can be solved within a restricted SCF for singlet excitations to avoid spin contamination. This also allows the straightforward application of post-SCF electron-correlation methods like MP2 or direct RPA methods. We present the details of our constraint-based orbital-optimized excited state method (COOX) and compare it to similar schemes. The accuracy of excitation energies will be analyzed for a benchmark of systems, while the quality of the resulting excited state densities is investigated by evaluating excited state nuclear forces and excited state structure optimizations. We also investigate the performance of the proposed COOX method for long-range charge transfer excitations and conical intersections with the ground-state.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Simulation of the non-adiabatic dynamics of an enone-Lewis acid complex in an explicit solvent},

author = {M T Peschel and J Kussmann and C Ochsenfeld and R De Vivie-Riedle},

url = {http://dx.doi.org/10.1039/D4CP02492C},

doi = {10.1039/D4CP02492C},

issn = {1463-9076},

year  = {2024},

date = {2024-08-28},

journal = {Physical Chemistry Chemical Physics},

volume = {26},

number = {35},

pages = {23256-23263},

abstract = {Unlocking the full potential of Lewis acid catalysis for photochemical transformations requires a comprehensive understanding of the ultrafast dynamics of substrate-Lewis acid complexes. In a previous article [Peschel et al., Angew. Chem. Int. Ed., 2021, 60, 10155], time-resolved spectroscopy supported by static calculations revealed that the Lewis acid remains attached during the relaxation of the model complex cyclohexenone-BF3. In contrast to the experimental observation, surface-hopping dynamics in the gas phase predicted ultrafast heterolytic dissociation. We attributed the discrepancy to missing solvent interactions. Thus, in this work, we present an interface between the SHARC and FermiONs++ program packages, which enables us to investigate the ultrafast dynamics of cyclohexenone-BF3 in an explicit solvent environment. Our simulations demonstrate that the solvent prevents the dissociation of the complex, leading to an intriguing dissociation\textendashreassociation mechanism. Comparing the dynamics with and without triplet states highlights their role in the relaxation process and shows that the Lewis acid inhibits intersystem crossing. These findings provide a clear picture of the relaxation process, which may aid in designing future Lewis acid catalysts for photochemical applications. They underscore that an explicit solvent model is required to describe relaxation processes in weakly bound states, as energy transfer to the solvent is crucial for the system to reach its minimum geometries.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Postsynthetic Transformation of Imine- into Nitrone-Linked Covalent Organic Frameworks for Atmospheric Water Harvesting at Decreased Humidity},

author = {L Grunenberg and G Savasci and S T Emmerling and F Heck and S Bette and A Cima Bergesch and C Ochsenfeld and B V Lotsch},

url = {https://doi.org/10.1021/jacs.3c02572},

doi = {10.1021/jacs.3c02572},

issn = {0002-7863},

year  = {2023},

date = {2023-05-25},

journal = {Journal of the American Chemical Society},

volume = {145},

number = {24},

pages = {13241-13248},

abstract = {Herein, we report a facile postsynthetic linkage conversion method giving synthetic access to nitrone-linked covalent organic frameworks (COFs) from imine- and amine-linked COFs. The new two-dimensional (2D) nitrone-linked covalent organic frameworks, NO-PI-3-COF and NO-TTI-COF, are obtained with high crystallinity and large surface areas. Nitrone-modified pore channels induce condensation of water vapor at 20% lower humidity compared to their amine- or imine-linked precursor COFs. Thus, the topochemical transformation to nitrone linkages constitutes an attractive approach to postsynthetically fine-tune water adsorption properties in framework materials.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Accelerating Hybrid Density Functional Theory Molecular Dynamics Simulations by Seminumerical Integration, Resolution-of-the-Identity Approximation, and Graphics Processing Units},

author = {H Laqua and J C B Dietschreit and J Kussmann and C Ochsenfeld},

url = {https://doi.org/10.1021/acs.jctc.2c00509},

doi = {10.1021/acs.jctc.2c00509},

issn = {1549-9618},

year  = {2022},

date = {2022-09-22},

journal = {Journal of Chemical Theory and Computation},

volume = {18},

number = {10},

pages = {6010-6020},

abstract = {The computationally very demanding evaluation of the 4-center-2-electron (4c2e) integrals and their respective integral derivatives typically represents the major bottleneck within hybrid Kohn\textendashSham density functional theory molecular dynamics simulations. Building upon our previous works on seminumerical exact-exchange (sn-LinK) [Laqua, H., Thompsons, T. H., Kussmann, J., Ochsenfeld, C., J. Chem. Theory Comput.2020,16, 1465] and resolution-of-the-identity Coulomb (RI-J) [Kussmann, J., Laqua, H., Ochsenfeld, C., J. Chem. Theory Comput.2021,17, 1512], the expensive 4c2e integral evaluation can be avoided entirely, resulting in a highly efficient electronic structure theory method, allowing for fast ab initio molecular dynamics (AIMD) simulations even with large basis sets. Moreover, we propose to combine the final self-consistent field (SCF) step with the subsequent nuclear forces evaluation, providing the forces at virtually no additional cost after a converged SCF calculation, reducing the total runtime of an AIMD simulation by about another 25%. In addition, multiple independent MD trajectories can be computed concurrently on a single node, leading to a greatly increased utilization of the available hardware─especially when combined with graphics processing unit acceleration─improving the overall throughput by up to another 5 times in this way. With all of those optimizations combined, our proposed method provides nearly 3 orders of magnitude faster execution times than traditional 4c2e integral-based methods. To demonstrate the practical utility of the approach, quantum-mechanical/molecular-mechanical dynamics simulations on double-stranded DNA were performed, investigating the relative hydrogen bond strength between adenine\textendashthymine and guanine\textendashcytosine base pairs. In addition, this illustrative application also contains a general accuracy assessment of the introduced approximations (integration grids, resolution-of-the-identity) within AIMD simulations, serving as a protocol on how to apply these new methods to practical problems.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Statistically optimal analysis of the extended-system adaptive biasing force (eABF) method},

author = {A Hulm and J C B Dietschreit and C Ochsenfeld},

url = {https://aip.scitation.org/doi/abs/10.1063/5.0095554},

doi = {10.1063/5.0095554},

year  = {2022},

date = {2022-07-13},

journal = {The Journal of Chemical Physics},

volume = {157},

number = {2},

pages = {024110},

abstract = {The extended-system adaptive biasing force (eABF) method and its newer variants offer rapid exploration of the configuration space of chemical systems. Instead of directly applying the ABF bias to collective variables, they are harmonically coupled to fictitious particles, which separates the problem of enhanced sampling from that of free energy estimation. The prevalent analysis method to obtain the potential of mean force (PMF) from eABF is thermodynamic integration. However, besides the PMF, most information is lost as the unbiased probability of visited configurations is never recovered. In this contribution, we show how statistical weights of individual frames can be computed using the Multistate Bennett’s Acceptance Ratio (MBAR), putting the post-processing of eABF on one level with other frequently used sampling methods. In addition, we apply this formalism to the prediction of nuclear magnetic resonance shieldings, which are very sensitive to molecular geometries and often require extensive sampling. The results show that the combination of enhanced sampling by means of extended-system dynamics with the MBAR estimator is a highly useful tool for the calculation of ensemble properties. Furthermore, the extension of the presented scheme to the recently published Gaussian-accelerated molecular dynamics eABF hybrid is straightforward and approximation free.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {From Free-Energy Profiles to Activation Free Energies},

author = {J C Dietschreit and D J Diestler and A Hulm and C Ochsenfeld and R G\'{o}mez-Bombarelli},

url = {https://arxiv.org/abs/2206.02893},

doi = {https://doi.org/10.48550/arXiv.2206.02893},

year  = {2022},

date = {2022-06-06},

journal = {arXiv preprint arXiv:2206.02893},

abstract = {Given a chemical reaction going from reactant (R) to the product (P) on a potential energy surface (PES) and a collective variable (CV) that discriminates between R and P, one can define a free-energy profile (FEP) as the logarithm of the marginal Boltzmann distribution of the CV. The FEP is not a true free energy, however, it is common to treat the FEP as the free-energy analog of the minimum energy path on the PES and to take the activation free energy, ΔF‡RP, as the difference between the maximum of the FEP at the transition state and the minimum at R. We show that this approximation can result in large errors. Since the FEP depends on the CV, it is therefore not unique, and different, discriminating CVs can yield different activation free energies for the same reaction. We derive an exact expression for the activation free energy that avoids this ambiguity with respect to the choice of CV. We find ΔF‡RP to be a combination of the probability of the system being in the reactant state, the probability density at the transition state surface, and the thermal de~Broglie wavelength associated with the transition from R to P. We then evaluate the activation free energies based on our formalism for simple analytic models and realistic chemical systems. The analytic models show that the widespread FEP-based approximation applies only at low temperatures for CVs for which the effective mass of the associated pseudo-particle is small. Most chemical reactions of practical interest involve polyatomic molecules with complex, high-dimensional PES that cannot be treated analytically and pose the added challenge of choosing a good CV, typically through heuristics. We study the influence of the choice of CV and find that, while the reaction free energy is largely unaffected, ΔF‡RP is quite sensitive.},

keywords = {},

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://doi.org/10.1002/adma.202107061},

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

issn = {0935-9648},

year  = {2022},

date = {2022-02-01},

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?42%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?5 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 = {},

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 = {},

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 = {},

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 = {},

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 = {},

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 = {},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {Highly Efficient Resolution-of-Identity Density Functional Theory Calculations on Central and Graphics Processing Units},

author = {J Kussmann and H Laqua and C Ochsenfeld},

url = {https://doi.org/10.1021/acs.jctc.0c01252},

doi = {10.1021/acs.jctc.0c01252},

issn = {1549-9618},

year  = {2021},

date = {2021-02-22},

journal = {Journal of Chemical Theory and Computation},

abstract = {We present an efficient method to evaluate Coulomb potential matrices using the resolution of identity approximation and semilocal exchange-correlation potentials on central (CPU) and graphics processing units (GPU). The new GPU-based RI-algorithm shows a high performance and ensures the favorable scaling with increasing basis set size as the conventional CPU-based method. Furthermore, our method is based on the J-engine algorithm [White; , Head-Gordon, J. Chem. Phys. 1996, 7, 2620], which allows for further optimizations that also provide a significant improvement of the corresponding CPU-based algorithm. Due to the increased performance for the Coulomb evaluation, the calculation of the exchange-correlation potential of density functional theory on CPUs quickly becomes a bottleneck to the overall computational time. Hence, we also present a GPU-based algorithm to evaluate the exchange-correlation terms, which results in an overall high-performance method for density functional calculations. The algorithms to evaluate the potential and nuclear derivative terms are discussed, and their performance on CPUs and GPUs is demonstrated for illustrative calculations.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {Photocatalytic Hydrogen Evolution: Interfacial Engineering for Improved Photocatalysis in a Charge Storing 2D Carbon Nitride: Melamine Functionalized Poly(heptazine imide) (Adv. Energy Mater. 6/2021)},

author = {J Kr\"{o}ger and A Jim\'{e}nez-Solano and G Savasci and P Rov\'{o} and I Moudrakovski and K K\"{u}ster and H Schlomberg and H A Vignolo-Gonz\'{a}lez and V Duppel and L Grunenberg and C B Dayan and M Sitti and F Podjaski and C Ochsenfeld and B V Lotsch},

url = {https://onlinelibrary.wiley.com/doi/abs/10.1002/aenm.202170028},

doi = {https://doi.org/10.1002/aenm.202170028},

issn = {1614-6832},

year  = {2021},

date = {2021-02-11},

journal = {Advanced Energy Materials},

volume = {11},

number = {6},

pages = {2170028},

abstract = {In article number 2003016, Bettina V. Lotsch and co-workers demonstrate that covalent surface modifications of the 2D carbon nitride poly(heptazine imide) with melamine groups strongly influence its polarity and photo(electrochemical) properties. This potent tuning pathway also results in the boosting of photocatalytic hydrogen evolution due to increased donor interactions and enhanced hole extraction.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Morphology Control in 2D Carbon Nitrides: Impact of Particle Size on Optoelectronic Properties and Photocatalysis},

author = {J Kr\"{o}ger and A Jim\'{e}nez-Solano and G Savasci and V W H Lau and V Duppel and I Moudrakovski and K K\"{u}ster and T Scholz and A Gouder and M-L Schreiber and F Podjaski and C Ochsenfeld and B V Lotsch},

url = {https://onlinelibrary.wiley.com/doi/abs/10.1002/adfm.202102468},

doi = {https://doi.org/10.1002/adfm.202102468},

issn = {1616-301X},

year  = {2021},

date = {2021-01-01},

urldate = {2021-01-01},

journal = {Advanced Functional Materials},

volume = {31},

number = {28},

pages = {2102468},

abstract = {Abstract The carbon nitride poly(heptazine imide), PHI, has recently emerged as a powerful 2D carbon nitride photocatalyst with intriguing charge storing ability. Yet, insights into how morphology, particle size, and defects influence its photophysical properties are virtually absent. Here, ultrasonication is used to systematically tune the particle size as well as concentration of surface functional groups and study their impact. Enhanced photocatalytic activity correlates with an optimal amount of those defects that create shallow trap states in the optical band gap, promoting charge percolation, as evidenced by time-resolved photoluminescence spectroscopy, charge transport studies, and quantum-chemical calculations. Excessive amounts of terminal defects can act as recombination centers and hence, decrease the photocatalytic activity for hydrogen evolution. Re-agglomeration of small particles can, however, partially restore the photocatalytic activity. The type and amount of trap states at the surface can also influence the deposition of the co-catalyst Pt, which is used in hydrogen evolution experiments. Optimized conditions entail improved Pt distribution, as well as enhanced wettability and colloidal stability. A description of the interplay between these effects is provided to obtain a holistic picture of the size\textendashproperty\textendashactivity relationship in nanoparticulate PHI-type carbon nitrides that can likely be generalized to related photocatalytic systems.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {Interfacial Engineering for Improved Photocatalysis in a Charge Storing 2D Carbon Nitride: Melamine Functionalized Poly(heptazine imide)},

author = {J Kr\"{o}ger and A Jim\'{e}nez-Solano and G Savasci and P Rov\'{o} and I Moudrakovski and K K\"{u}ster and H Schlomberg and H A Vignolo-Gonz\'{a}lez and V Duppel and L Grunenberg and C B Dayan and M Sitti and F Podjaski and C Ochsenfeld and B V Lotsch},

url = {https://onlinelibrary.wiley.com/doi/abs/10.1002/aenm.202003016},

doi = {https://doi.org/10.1002/aenm.202003016},

issn = {1614-6832},

year  = {2020},

date = {2020-12-21},

journal = {Advanced Energy Materials},

volume = {11},

number = {6},

pages = {2003016},

abstract = {Abstract Carbon nitrides constitute a class of earth-abundant polymeric semiconductors, which have high potential for tunability on a molecular level, despite their high chemical and thermal inertness. Here the first postsynthetic modification of the 2D carbon nitride poly(heptazine imide) (PHI) is reported, which is decorated with terminal melamine (Mel) moieties by a functional group interconversion. The covalent attachment of this group is verified based with a suite of spectroscopic and microscopic techniques supported by quantum\textendashchemical calculations. Using triethanolamine as a sacrificial electron donor, Mel-PHI outperforms most other carbon nitrides in terms of hydrogen evolution rate (5570 µmol h−1 g−1), while maintaining the intrinsic light storing properties of PHI. The origin of the observed superior photocatalytic performance is traced back to a modified surface electronic structure and enhanced interfacial interactions with the amphiphile triethanolamine, which imparts improved colloidal stability to the catalyst particles especially in contrast to methanol used as donor. However, this high activity can be limited by oxidation products of donor reversibly building up at the surface, thus blocking active centers. The findings lay out the importance of surface functionalization to engineer the catalyst\textendashsolution interface, an underappreciated tuning parameter in photocatalytic reaction design.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {A Fermi smearing variant of the Tamm\textendashDancoff approximation for nonadiabatic dynamics involving S1\textendashS0 transitions: Validation and application to azobenzene},

author = {L D M Peters and J Kussmann and C Ochsenfeld},

url = {https://aip.scitation.org/doi/abs/10.1063/5.0016487},

doi = {10.1063/5.0016487},

year  = {2020},

date = {2020-09-02},

journal = {The Journal of Chemical Physics},

volume = {153},

number = {9},

pages = {094104},

abstract = {The main shortcoming of time-dependent density functional theory (TDDFT) regarding its use for nonadiabatic molecular dynamics (NAMD) is its incapability to describe conical intersections involving the ground state. To overcome this problem, we combine Fermi smearing (FS) DFT with a fractional-occupation variant of the Tamm\textendashDancoff approximation (TDA) of TDDFT in the generalized gradient approximation. The resulting method (which we denote as FS-TDA) gives access to ground- and excited-state energies, gradients, and nonadiabatic coupling vectors, which are physically correct even in the vicinity of S1\textendashS0 conical intersections. This is shown for azobenzene, a widely used photoswitch, via single point calculations and NAMD simulations of its cis\textendashtrans photoisomerization. We conclude that FS-TDA may be used as an efficient alternative to investigate these processes.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {Ionothermal Synthesis of Imide-Linked Covalent Organic Frameworks},

author = {J Maschita and T Banerjee and G Savasci and F Haase and C Ochsenfeld and B V Lotsch},

url = {https://doi.org/10.1002/anie.202007372},

doi = {https://doi.org/10.1002/anie.202007372},

issn = {1433-7851},

year  = {2020},

date = {2020-09-01},

journal = {Angewandte Chemie International Edition},

volume = {59},

number = {36},

pages = {15750-15758},

abstract = {Abstract Covalent organic frameworks (COFs) are an extensively studied class of porous materials, which distinguish themselves from other porous polymers in their crystallinity and high degree of modularity, enabling a wide range of applications. COFs are most commonly synthesized solvothermally, which is often a time-consuming process and restricted to well-soluble precursor molecules. Synthesis of polyimide-linked COFs (PI-COFs) is further complicated by the poor reversibility of the ring-closing reaction under solvothermal conditions. Herein, we report the ionothermal synthesis of crystalline and porous PI-COFs in zinc chloride and eutectic salt mixtures. This synthesis does not require soluble precursors and the reaction time is significantly reduced as compared to standard solvothermal synthesis methods. In addition to applying the synthesis to previously reported imide COFs, a new perylene-based COF was also synthesized, which could not be obtained by the classical solvothermal route. In situ high-temperature XRPD analysis hints to the formation of precursor?salt adducts as crystalline intermediates, which then react with each other to form the COF.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Disorder and Linker Deficiency in Porphyrinic Zr-MOFs: Resolving the Zr8O6 Cluster Conundrum in PCN-221},

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

url = {http://europepmc.org/abstract/PPR/PPR210987 

https://doi.org/10.26434/chemrxiv.12918968.v1},

doi = {10.26434/chemrxiv.12918968.v1},

year  = {2020},

date = {2020-09-01},

urldate = {2020-09-01},

publisher = {ChemRxiv},

abstract = {Porphyrin-based metal-organic frameworks (MOFs), exemplified by the prototypical representatives MOF-525, PCN-221, and PCN-224 are among the most promising MOF 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, we reveal the type and disorder of the Zr-clusters based on a comprehensive synthetic and structural analysis spanning local and long-range length scales. Our analysis on PCN-221 reveals Zr6O4(OH)4 clusters in four distinct orientations within the unit cell, rather than Zr8O6 clusters as originally published, accompanied by random linker vacancies around 50%. 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\textemdashlinker 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 = {},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {Rational Design of Covalent Cobaloxime-Covalent Organic Framework Hybrids for Enhanced Photocatalytic Hydrogen Evolution},

author = {K Gottschling and G Savasci and H Vignolo-Gonzalez and S Schmidt and P Mauker and T Banerjee and P Rovo and C Ochsenfeld and B V Lotsch},

url = {\<Go to ISI\>://WOS:000551495700030},

doi = {10.1021/jacs.0c02155},

issn = {0002-7863},

year  = {2020},

date = {2020-07-15},

journal = {Journal of the American Chemical Society},

volume = {142},

number = {28},

pages = {12146-12156},

abstract = {Covalent organic frameworks (COFs) display a unique combination of chemical tunability, structural diversity, high porosity, nanoscale regularity, and thermal stability. Recent efforts are directed at using such frameworks as tunable scaffolds for chemical reactions. In particular, COFs have emerged as viable platforms for mimicking natural photosynthesis. However, there is an indisputable need for efficient, stable, and economical alternatives for the traditional platinum-based cocatalysts for light-driven hydrogen evolution. Here, we present azide-functionalized chloro(pyridine)cobaloxime hydrogen-evolution cocatalysts immobilized on a hydrazone-based COF-42 backbone that show improved and prolonged photocatalytic activity with respect to equivalent physisorbed systems. Advanced solid-state NMR and quantum-chemical methods allow us to elucidate details of the improved photoreactivity and the structural composition of the involved active site. We found that a genuine interaction between the COF backbone and the cobaloxime facilitates recoordination of the cocatalyst during the photoreaction, thereby improving the reactivity and hindering degradation of the catalyst. The excellent stability and prolonged reactivity make the herein reported cobaloxime-tethered COF materials promising hydrogen evolution catalysts for future solar fuel technologies.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {Important components for accurate hyperfine coupling constants: electron correlation, dynamic contributions, and solvation effects},

author = {S Vogler and J C B Dietschreit and L D M Peters and C Ochsenfeld},

url = {\<Go to ISI\>://WOS:000543577500001},

doi = {10.1080/00268976.2020.1772515},

issn = {0026-8976},

year  = {2020},

date = {2020-06-03},

journal = {Molecular Physics},

abstract = {The calculation of hyperfine coupling constants is a challenging task in balancing accuracy and computational effort. While previous work has shown the importance of electron correlation and molecular dynamic contributions, we present a systematic study simultaneously analyzing the influence of both effects on hyperfine coupling constants. To this end, we thoroughly study two organic radicals, namely the dimethylamino radical and ethanal radical cation, proving the need to account for conformational flexibility as well as the large influence of electron correlation. Based on these results, we analyse the effect of electron correlation and dynamic simulations on a set of 12 organic radicals, illustrating that both effects are vital for an accuratein silicodescription on the same scale. Furthermore, we study the influence of solvation using the efficient nuclei-selected algorithm to obtain hyperfine coupling constants with electron correlation for large systems, indicating the necessity to include explicit solvent molecules. Finally, we introduce a composite approach to incorporate all contributions for hyperfine coupling of radicals in solution at comparatively low computational cost. This is successfully tested on the hydroxylated TEMPO radical in aqueous solution, where we are able to compute aN-HFCC of 44.4 MHz compared to the experimentally measured 47.6 MHz. [GRAPHICS] .},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Combining Graphics Processing Units, Simplified Time-Dependent Density Functional Theory, and Finite-Difference Couplings to Accelerate Nonadiabatic Molecular Dynamics},

author = {L D M Peters and J Kussmann and C Ochsenfeld},

url = {https://doi.org/10.1021/acs.jpclett.0c00320},

doi = {10.1021/acs.jpclett.0c00320},

year  = {2020},

date = {2020-05-06},

journal = {The Journal of Physical Chemistry Letters},

volume = {11},

number = {10},

pages = {3955-3961},

abstract = {Starting from our recently published implementation of nonadiabatic molecular dynamics (NAMD) on graphics processing units (GPUs), we explore further approaches to accelerate ab initio NAMD calculations at the time-dependent density functional theory (TDDFT) level of theory. We employ (1) the simplified TDDFT schemes of Grimme et al. and (2) the Hammes-Schiffer\textendashTully approach to obtain nonadiabatic couplings from finite-difference calculations. The resulting scheme delivers an accurate physical picture while virtually eliminating the two computationally most demanding steps of the algorithm. Combined with our GPU-based integral routines for SCF, TDDFT, and TDDFT derivative calculations, NAMD simulations of systems of a few hundreds of atoms at a reasonable time scale become accessible on a single compute node. To demonstrate this and to present a first, illustrative example, we perform TDDFT/MM-NAMD simulations of the rhodopsin protein.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Nonadiabatic Molecular Dynamics on Graphics Processing Units: Performance and Application to Rotary Molecular Motors},

author = {L D M Peters and J Kussmann and C Ochsenfeld},

url = {https://doi.org/10.1021/acs.jctc.9b00859},

doi = {10.1021/acs.jctc.9b00859},

issn = {1549-9618},

year  = {2019},

date = {2019-11-25},

journal = {Journal of Chemical Theory and Computation},

volume = {15},

number = {12},

pages = {6647-6659},

abstract = {Nonadiabatic molecular dynamics (NAMD) simulations of molecular systems require the efficient evaluation of excited-state properties, such as energies, gradients, and nonadiabatic coupling vectors. Here, we investigate the use of graphics processing units (GPUs) in addition to central processing units (CPUs) to efficiently calculate these properties at the time-dependent density functional theory (TDDFT) level of theory. Our implementation in the FermiONs++ program package uses the J-engine and a preselective screening procedure for the calculation of Coulomb and exchange kernels, respectively. We observe good speed-ups for small and large molecular systems (comparable to those observed in ground-state calculations) and reduced (down to sublinear) scaling behavior with respect to the system size (depending on the spatial locality of the investigated excitation). As a first illustrative application, we present efficient NAMD simulations of a series of newly designed light-driven rotary molecular motors and compare their S1 lifetimes. Although all four rotors show different S1 excitation energies, their ability to rotate upon excitation is conserved, making the series an interesting starting point for rotary molecular motors with tunable excitation energies.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {Structural Insights into Poly(Heptazine Imides): A Light Storing Carbon Nitride Material for Dark Photocatalysis},

author = {H Schlomberg and J Kr\"{o}ger and G Savasci and M Terban and S Bette and I Moudrakovski and V Duppel and F Podjaski and R Siegel and J Senker and R Dinnebier and C Ochsenfeld and B V Lotsch},

doi = {10.1021/acs.chemmater.9b02199},

year  = {2019},

date = {2019-08-12},

journal = {Chemistry of Materials},

volume = {31},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {Low-Scaling Self-Consistent Minimization of a Density Matrix Based Random Phase Approximation Method in the Atomic Orbital Space},

author = {D Graf and M Beuerle and C Ochsenfeld},

url = {\<Go to ISI\>://WOS:000480826800016},

doi = {10.1021/acs.jctc.9b00444},

issn = {1549-9618},

year  = {2019},

date = {2019-08-01},

journal = {Journal of Chemical Theory and Computation},

volume = {15},

number = {8},

pages = {4468-4477},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {Sustained Solar H-2 Evolution from a Thiazolo 5,4-d thiazole-Bridged Covalent Organic Framework and Nickel-Thiolate Cluster in Water},

author = {B P Biswal and H A Vignolo-Gonzalez and T Banerjee and L Grunenberg and G Savasci and K Gottschling and J Nuss and C Ochsenfeld and B V Lotsch},

url = {\<Go to ISI\>://WOS:000476684700023},

doi = {10.1021/jacs.9b03243},

issn = {0002-7863},

year  = {2019},

date = {2019-06-20},

journal = {Journal of the American Chemical Society},

volume = {141},

number = {28},

pages = {11082-11092},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {Sub-stoichiometric 2D covalent organic frameworks from tri- and tetratopic linkers},

author = {T Banerjee and F Haase and S Trenker and B P Biswal and G Savasci and V Duppel and I Moudrakovski and C Ochsenfeld and B V Lotsch},

url = {\<Go to ISI\>://WOS:000472032300004},

doi = {10.1038/s41467-019-10574-6},

issn = {2041-1723},

year  = {2019},

date = {2019-06-19},

journal = {Nature Communications},

volume = {10},

keywords = {},

pubstate = {published},

tppubtype = {article}

}