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@article{nokey,

title = {Applying an Anti-Kasha Model Resolves Differences Between Photosynthetic and Artificial Pigments},

author = {J P G\"{o}tze and S Petry and S Reiter and H Lokstein and R De Vivie-Riedle},

url = {\<Go to ISI\>://WOS:001535152400001},

doi = {10.1021/acs.jpcb.5c02465},

issn = {1520-6106},

year  = {2025},

date = {2025-08-07},

journal = {Journal of Physical Chemistry B},

volume = {129},

number = {31},

pages = {7884-7895},

abstract = {The current interpretation of excitation energy transfer (EET) processes in natural photosynthesis generally relies on Kasha's rule, suggesting that internal conversion (IC) processes usually outpace any EET between higher excited states. It is, however, known from research on artificial systems that Kasha's rule does not apply to many dyes, especially when found in assembled clusters analogous to photosynthetic chlorophyll (Chl)-protein complexes. In this contribution, a semiempirical Forster-type model is applied to otherwise well-investigated pigments of natural photosynthesis (Chls a, b, c1 and various carotenoids). Strong potential for anti-Kasha processes is identified in all investigated pigments, based on their high Coulomb coupling elements, similar to compounds with already known anti-Kasha properties. The pigments are further found to form strongly delocalized excitons, especially between the higher excited states usually responsible for anti-Kasha pathways. Test calculations with different pigment compositions for various natural light harvesting complexes (LHCII, CP24, CP26, CP29, FCP) demonstrate how the higher band EET network and absorbance could be affected by the presence of accessory pigments: Chl a-only networks should perform anti-Kasha EET, but this is suppressed by the presence of accessory pigments via several mechanisms (exciton disruption, spectral competition, energy sinks and fast, non-Chl a IC). The apparent "special" behavior of photosynthetic systems is thus resolved as the result of pigment mixtures.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Coupled Nuclear and Electron Dynamics in Chlorophyll Unraveled by XMS-CASPT2 X-ray Absorption Spectra},

author = {L B\"{a}uml and R De Vivie-Riedle},

url = {https://doi.org/10.1021/acs.jpcb.4c07787},

doi = {10.1021/acs.jpcb.4c07787},

issn = {1520-6106},

year  = {2025},

date = {2025-02-27},

journal = {The Journal of Physical Chemistry B},

volume = {129},

number = {8},

pages = {2159-2167},

abstract = {Attosecond spectroscopy, especially time-resolved X-ray absorption spectra (XAS), enables direct observation of ultrafast molecular dynamics. The complementary and even preceding development of theoretical simulations can offer the necessary guidance and stimulate new experiments. In this work, we simulated high-level XAS for the magnesium and nitrogen K-edge of chlorophyll a. In our previous work on the ultrafast relaxation process in the Q-band, our quantum dynamics simulations found the Qx and Qy states to be energetically close and therefore strongly coupled. Here, we analyze the strong coupling between Qx and Qy via XAS, indicating promising possibilities for experimental observation. The excited-state energies, potential energy surfaces, and XAS are computed at the XMS-CASPT2 level of theory to capture the complex multireference character of chlorophyll excitations. In our simulated spectra, we could follow the ultrafast population transfer between Qx and Qy and thus draw conclusions about the strong vibrational coupling between them.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Reassessing the role and lifetime of Qx in the energy transfer dynamics of chlorophyll a},

author = {E Keil and A Kumar and L B\"{a}uml and S Reiter and E Thyrhaug and S Moser and C D P Duffy and R De Vivie-Riedle and J Hauer},

url = {http://dx.doi.org/10.1039/D4SC06441K},

doi = {10.1039/D4SC06441K},

issn = {2041-6520},

year  = {2024},

date = {2024-11-27},

journal = {Chemical Science},

abstract = {Chlorophylls are photoactive molecular building blocks essential to most photosynthetic systems. They have comparatively simple optical spectra defined by states with near-orthogonal transition dipole moments, referred to as Bx and By in the blue/green spectral region, and Qx and Qy in the red. Underlying these spectra is a surprisingly complex electronic structure, where strong electronic-vibrational interactions are crucial to the description of state characters. Following photoexcitation, energy-relaxation between these states is extremely fast and connected to only modest changes in spectral shapes. This has pushed conventional theoretical and experimental methods to their limits and left the energy transfer pathway under debate. In this work, we address the electronic structure and photodynamics of chlorophyll a using polarization-controlled static \textendash and ultrafast \textendash optical spectroscopies. We support the experimental data analysis with quantum dynamical simulations and effective heat dissipation models. We find clear evidence for B → Q transfer on a timescale of ∼100 fs and identify Qx signatures within fluorescence excitation and transient spectra. However, Qx is populated only fleetingly, with a lifetime well below our ∼30 fs experimental time resolution. Outside of these timescales, the kinetics are determined by vibrational relaxation and cooling. Despite its ultrashort lifetime, our theoretical analysis suggests that Qx plays a crucial role as a bridging state in B → Q energy transfer. In summary, our findings present a unified and consistent picture of chlorophyll relaxation dynamics based on ultrafast and polarization-resolved spectroscopic techniques supported by extensive theoretical models; they clarify the role of Qx in the energy deactivation network of chlorophyll a.},

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 = {Molecular interactions of photosystem I and ZIF-8 in bio-nanohybrid materials},

author = {S Reiter and I Gordiy and K L Kollmannsberger and F Liu and E Thyrhaug and D Leister and J Warnan and J Hauer and R De Vivie-Riedle},

url = {http://dx.doi.org/10.1039/D4CP03021D},

doi = {10.1039/D4CP03021D},

issn = {1463-9076},

year  = {2024},

date = {2024-08-22},

journal = {Physical Chemistry Chemical Physics},

volume = {26},

number = {35},

pages = {23228-23239},

abstract = {Bio-nanohybrid devices featuring natural photocatalysts bound to a nanostructure hold great promise in the search for sustainable energy conversion. One of the major challenges of integrating biological systems is protecting them against harsh environmental conditions while retaining, or ideally enhancing their photophysical properties. In this mainly computational work we investigate an assembly of cyanobacterial photosystem I (PS I) embedded in a metal\textendashorganic framework (MOF), namely the zeolitic imidazolate framework ZIF-8. This complex has been reported experimentally [Bennett et al., Nanoscale Adv., 2019, 1, 94] but so far the molecular interactions between PS I and the MOF remained elusive. We show via absorption spectroscopy that PS I remains intact throughout the encapsulation-release cycle. Molecular dynamics (MD) simulations further confirm that the encapsulation has no noticeable structural impact on the photosystem. However, the MOF building blocks frequently coordinate to the Mg2+ ions of chlorophylls in the periphery of the antenna complex. High-level quantum mechanical calculations reveal charge-transfer interactions, which affect the excitonic network and thereby may reversibly change the fluorescence properties of PS I. Nevertheless, our results highlight the stability of PS I in the MOF, as the reaction center remains unimpeded by the heterogeneous environment, paving the way for applications in the foreseeable future.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Determining Excited-State Absorption Properties of a Quinoid Flavin by Polarization-Resolved Transient Spectroscopy},

author = {Y Xu and M T Peschel and M J\"{a}nchen and R Foja and G Storch and E Thyrhaug and R De Vivie-Riedle and J Hauer},

url = {https://doi.org/10.1021/acs.jpca.4c01260},

doi = {10.1021/acs.jpca.4c01260},

issn = {1089-5639},

year  = {2024},

date = {2024-05-16},

journal = {The Journal of Physical Chemistry A},

volume = {128},

number = {19},

pages = {3830-3839},

abstract = {As important naturally occurring chromophores, photophysical/chemical properties of quinoid flavins have been extensively studied both experimentally and theoretically. However, little is known about the transition dipole moment (TDM) orientation of excited-state absorption transitions of these important compounds. This aspect is of high interest in the fields of photocatalysis and quantum control studies. In this work, we employ polarization-associated spectra (PAS) to study the excited-state absorption transitions and the underlying TDM directions of a standard quinoid flavin compound. As compared to transient absorption anisotropy (TAA), an analysis based on PAS not only avoids diverging signals but also retrieves the relative angle for ESA transitions with respect to known TDM directions. Quantum chemical calculations of excited-state properties lead to good agreement with TA signals measured in magic angle configuration. Only when comparing experiment and theory for TAA spectra and PAS, do we find deviations when and only when the S0 → S1 of flavin is used as a reference. We attribute this to the vibronic coupling of this transition to a dark state. This effect is only observed in the employed polarization-controlled spectroscopy and would have gone unnoticed in conventional TA.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Thermal site energy fluctuations in photosystem I: new insights from MD/QM/MM calculations},

author = {S Reiter and F L Kiss and J Hauer and R De Vivie-Riedle},

url = {http://dx.doi.org/10.1039/D2SC06160K},

doi = {10.1039/D2SC06160K},

issn = {2041-6520},

year  = {2023},

date = {2023-02-06},

journal = {Chemical Science},

volume = {14},

number = {12},

pages = {3117-3131},

abstract = {Cyanobacterial photosystem I (PSI) is one of the most efficient photosynthetic machineries found in nature. Due to the large scale and complexity of the system, the energy transfer mechanism from the antenna complex to the reaction center is still not fully understood. A central element is the accurate evaluation of the individual chlorophyll excitation energies (site energies). Such an evaluation must include a detailed treatment of site specific environmental influences on structural and electrostatic properties, but also their evolution in the temporal domain, because of the dynamic nature of the energy transfer process. In this work, we calculate the site energies of all 96 chlorophylls in a membrane-embedded model of PSI. The employed hybrid QM/MM approach using the multireference DFT/MRCI method in the QM region allows to obtain accurate site energies under explicit consideration of the natural environment. We identify energy traps and barriers in the antenna complex and discuss their implications for energy transfer to the reaction center. Going beyond previous studies, our model also accounts for the molecular dynamics of the full trimeric PSI complex. Via statistical analysis we show that the thermal fluctuations of single chlorophylls prevent the formation of a single prominent energy funnel within the antenna complex. These findings are also supported by a dipole exciton model. We conclude that energy transfer pathways may form only transiently at physiological temperatures, as thermal fluctuations overcome energy barriers. The set of site energies provided in this work sets the stage for theoretical and experimental studies on the highly efficient energy transfer mechanisms in PSI.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Q-Band relaxation in chlorophyll: new insights from multireference quantum dynamics},

author = {S Reiter and L B\"{a}uml and J Hauer and R De Vivie-Riedle},

url = {http://dx.doi.org/10.1039/D2CP02914F},

doi = {10.1039/D2CP02914F},

issn = {1463-9076},

year  = {2022},

date = {2022-10-27},

journal = {Physical Chemistry Chemical Physics},

abstract = {The ultrafast relaxation within the Q-bands of chlorophyll plays a crucial role in photosynthetic light-harvesting. Yet, despite being the focus of many experimental and theoretical studies, it is still not fully understood. In this paper we look at the relaxation process from the perspective of non-adiabatic wave packet dynamics. For this purpose, we identify vibrational degrees of freedom which contribute most to the non-adiabatic coupling. Using a selection of normal modes, we construct four reduced-dimensional coordinate spaces and investigate the wave packet dynamics on XMS-CASPT2 potential energy surfaces. In this context, we discuss the associated computational challenges, as many quantum chemical methods overestimate the Qx\textendashQy energy gap. Our results show that the Qx and Qy potential energy surfaces do not cross in an energetically accessible region of the vibrational space. Instead, non-adiabatic coupling facilitates ultrafast population transfer across the potential energy surface. Moreover, we can identify the excited vibrational eigenstates that take part in the relaxation process. We conclude that the Q-band system of chlorophyll a should be viewed as a strongly coupled system, where population is easily transferred between the x and y-polarized electronic states. This suggests that both orientations may contribute to the electron transfer in the reaction center of photosynthetic light-harvesting systems.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Sub-optical-cycle light-matter energy transfer in molecular vibrational spectroscopy},

author = {M T Peschel and M H\"{o}gner and T Buberl and D Keefer and R De Vivie-Riedle and I Pupeza},

url = {https://doi.org/10.1038/s41467-022-33477-5},

doi = {10.1038/s41467-022-33477-5},

issn = {2041-1723},

year  = {2022},

date = {2022-10-06},

journal = {Nature Communications},

volume = {13},

number = {1},

pages = {5897},

abstract = {The evolution of ultrafast-laser technology has steadily advanced the level of detail in studies of light-matter interactions. Here, we employ electric-field-resolved spectroscopy and quantum-chemical modelling to precisely measure and describe the complete coherent energy transfer between octave-spanning mid-infrared waveforms and vibrating molecules in aqueous solution. The sub-optical-cycle temporal resolution of our technique reveals alternating absorption and (stimulated) emission on a few-femtosecond time scale. This behaviour can only be captured when effects beyond the rotating wave approximation are considered. At a femtosecond-to-picosecond timescale, optical-phase-dependent coherent transients and the dephasing of the vibrations of resonantly excited methylsulfonylmethane (DMSO2) are observed. Ab initio modelling using density functional theory traces these dynamics back to molecular-scale sample properties, in particular vibrational frequencies and transition dipoles, as well as their fluctuation due to the motion of DMSO2 through varying solvent environments. Future extension of our study to nonlinear interrogation of higher-order susceptibilities is fathomable with state-of-the-art lasers.},

keywords = {},

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 = {},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {Electro-mediated PhotoRedox Catalysis for Selective C(sp3)-O Cleavages of Phosphinated Alcohols to Carbanions},

author = {X Tian and T A Karl and S Reiter and S Yakubov and R De Vivie-Riedle and B Koenig and J P Barham},

url = {https://onlinelibrary.wiley.com/doi/abs/10.1002/anie.202105895},

doi = {https://doi.org/10.1002/anie.202105895},

issn = {1433-7851},

year  = {2021},

date = {2021-06-24},

urldate = {2021-06-24},

journal = {Angewandte Chemie International Edition},

volume = {n/a},

number = {n/a},

abstract = {We report a novel example of electro-mediated photoredox catalysis (e-PRC) in the reductive cleavage of C(sp 3 )-O bonds of phosphinated alcohols to alkyl carbanions. As well as deoxygenations, olefinations are reported which are E -selective and can be made Z -selective in a tandem reduction/photosensitization process where both steps are photoelectrochemically promoted. Spectroscopy, computation and catalyst structural variations reveal that our new naphthalene monoimide-type catalyst allows for a more intimate dispersive precomplexation of its radical anion form with the phosphinate substrate, facilitating a reactivity-determining C(sp 3 )-O cleavage. Surprisingly and in contrast to previously reported photoexcited radical anion chemistries, our conditions i) tolerate aryl chlorides/bromides and ii) do not give rise to Birch-type reductions.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {Electronic and Geometric Characterization of TICT Formation in Hemithioindigo Photoswitches by Picosecond Infrared Spectroscopy},

author = {K Stallhofer and M Nuber and F Sch\"{u}ppel and S Thumser and H Iglev and R De Vivie-Riedle and W Zinth and H Dube},

url = {https://doi.org/10.1021/acs.jpca.1c02646},

doi = {10.1021/acs.jpca.1c02646},

issn = {1089-5639},

year  = {2021},

date = {2021-05-14},

urldate = {2021-05-14},

journal = {The Journal of Physical Chemistry A},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {Activation of 2-Cyclohexenone by BF3 Coordination: Mechanistic Insights from Theory and Experiment},

author = {M Peschel and P Kabacinski and D P Schwinger and E Thyrhaug and G Cerullo and T Bach and J Hauer and R De Vivie-Riedle

},

url = {https://onlinelibrary.wiley.com/doi/abs/10.1002/anie.202016653},

doi = {https://doi.org/10.1002/anie.202016653},

issn = {1433-7851},

year  = {2021},

date = {2021-02-17},

urldate = {2021-02-17},

journal = {Angewandte Chemie International Edition},

volume = {n/a},

number = {n/a},

abstract = {Lewis acids have recently been recognized as catalysts enabling enantioselective photochemical transformations. Mechanistic studies on these systems are however rare, either due to their absorption at wavelengths shorter than 260 nm, or due to the limitations of theoretical dynamic studies for larger complexes. In this work, we overcome these challenges and employ sub-30-fs transient absorption in the UV, in combination with a highly accurate theoretical treatment on the XMS-CASPT2 level. We investigate 2-cyclohexenone and its complex to boron trifluoride and analyze the observed dynamics based on trajectory calculations including non-adiabatic coupling and intersystem crossing. This approach explains all ultrafast decay pathways observed in the complex. We show that the Lewis acid remains attached to the substrate in the triplet state, which in turn explains why chiral boron-based Lewis acids induce a high enantioselectivity in photocycloaddition reactions.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Multiscale Conformational Sampling Reveals Excited-State Locality in DNA Self-Repair Mechanism},

author = {V Piccinni and S Reiter and D Keefer and R De Vivie-Riedle},

url = {https://doi.org/10.1021/acs.jpca.0c07207},

doi = {10.1021/acs.jpca.0c07207},

issn = {1089-5639},

year  = {2020},

date = {2020-10-22},

urldate = {2020-10-22},

journal = {The Journal of Physical Chemistry A},

volume = {124},

number = {44},

pages = {9133-9140},

abstract = {Ultraviolet (UV) irradiation is known to be responsible for DNA damage. However, experimental studies in DNA oligonucleotides have shown that UV light can also induce sequence-specific self-repair. Following charge transfer from a guanine adenine sequence adjacent to a cyclobutane pyrimidine dimer (CPD), the covalent bond between the two thymines could be cleaved, recovering the intact base sequence. Mechanistic details promoting the self-repair remained unclear, however. In our theoretical study, we investigated whether optical excitation could directly lead to a charge-transfer state, thereby initiating the repair, or whether the initial excited state remains localized on a single nucleobase. We performed conformational sampling of 200 geometries of the damaged DNA double strand solvated in water and used a hybrid quantum and molecular mechanics approach to compute excited states at the complete active space perturbation level of theory. Analysis of the conformational data set clearly revealed that the excited-state properties are uniformly distributed across the fluctuations of the nucleotide in its natural environment. From the electronic wavefunction, we learned that the electronic transitions remained predominantly local on either adenine or guanine, and no direct charge transfer occurred in the experimentally accessed energy range. The investigated base sequence is not only specific to the CPD repair mechanism but ubiquitously occurs in nucleic acids. Our results therefore give a very general insight into the charge locality of UV-excited DNA, a property that is regarded to have determining relevance in the structural consequences following absorption of UV photons.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {Regio- and diastereoselective reactions of chiral secondary alkylcopper reagents with propargylic phosphates: preparation of chiral allenes},

author = {J Skotnitzki and A Kremsmair and D Keefer and F Schuppel and B L De Bonneville and R De Vivie-Riedle and P Knochel},

url = {\<Go to ISI\>://WOS:000537133000020},

doi = {10.1039/c9sc05982b},

issn = {2041-6520},

year  = {2020},

date = {2020-05-28},

journal = {Chemical Science},

volume = {11},

number = {20},

pages = {5328-5332},

abstract = {The diastereoselective S(N)2 '-substitution of secondary alkylcopper reagents with propargylic phosphates enables the preparation of stereodefined alkylallenes. By using enantiomerically enriched alkylcopper reagents and enantioenriched propargylic phosphates as electrophiles anti-S(N)2 '-substitutions were performend leading to alpha-chiral allenes in good yields with excellent regioselectivity and retention of configuration. DFT-calculations were performed to rationalize the structure of these alkylcopper reagents in various solvents, emphasizing their configurational stability in THF.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {Excited State Conformations of Bridged and Unbridged Pyrene Excimers},

author = {S Reiter and M K Roos and R De Vivie-Riedle},

url = {\<Go to ISI\>://WOS:000487014600024},

doi = {10.1002/cptc.201900096},

issn = {2367-0932},

year  = {2019},

date = {2019-05-06},

journal = {Chemphotochem},

volume = {3},

number = {9},

pages = {881-888},

keywords = {},

pubstate = {published},

tppubtype = {article}

}