TY  - JOUR
A1  - Wohlgemuth, Matthias
A1  - Mitric, Roland
T1  - Photochemical Chiral Symmetry Breaking in Alanine
JF  - Journal of Physical Chemistry A
N2  - We introduce a general theoretical approach for the simulation of photochemical dynamics under the influence of circularly polarized light to explore the possibility of generating enantiomeric enrichment through polarized-light-selective photochemistry. The method is applied to the simulation of the photolysis of alanine, a prototype chiral amino acid. We show that a systematic enantiomeric enrichment can be obtained depending on the helicity of the circularly polarized light that induces the excited-state photochemistry of alanine. By analyzing the patterns of the photoinduced fragmentation of alanine we find an inducible enantiomeric enrichment up to 1.7%, which is also in good correspondence to the experimental findings. Our method is generally applicable to complex systems and might serve to systematically explore the photochemical origin of homochirality.
KW  - circularly-polarized light
KW  - amino-acids
KW  - homochirality
KW  - molecular dynamics
KW  - dichroism
Y1  - 2016
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-158557
UR  - https://pubs.acs.org/doi/10.1021/acs.jpca.6b07611
N1  - This document is the Accepted Manuscript version of a Published Work that appeared in final form in Journal of Physical Chemistry A, copyright © American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see https://pubs.acs.org/doi/10.1021/acs.jpca.6b07611
VL  - 45
IS  - 120
ER  - 
TY  - INPR
A1  - Wohlgemuth, Matthias
A1  - Mitric, Roland
T1  - Excitation energy transport in DNA modelled by multi-chromophoric field-induced surface hopping
T2  - Physical Chemistry Chemical Physics
N2  - Absorption of ultraviolet light is known as a major source of carcinogenic mutations of DNA. The underlying processes of excitation energy dissipation are yet not fully understood. In this work we provide a new and generally applicable route for studying the excitation energy transport in multi-chromophoric complexes at an atomistic level. The surface-hopping approach in the frame of the extended Frenkel exciton model combined with QM/MM techniques allowed us to simulate the photodynamics of the alternating (dAdT)10 : (dAdT)10 double-stranded DNA. In accordance with recent experiments, we find that the excited state decay is multiexponential, involving a long and a short component which are due to two distinct mechanisms: formation of long-lived delocalized excitonic and charge transfer states vs. ultrafast decaying localized states resembling those of the bare nucleobases. Our simulations explain all stages of the ultrafast photodynamics including initial photoexcitation, dynamical evolution out of the Franck-Condon region, excimer formation and nonradiative relaxation to the ground state.
KW  - Photodynamics
KW  - DNA
Y1  - 2020
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-209467
ET  - submitted version
ER  - 
TY  - JOUR
A1  - Wohlgemuth, Matthias
A1  - Miyazaki, Mitsuhiko
A1  - Tsukada, Kohei
A1  - Weiler, Martin
A1  - Dopfer, Otto
A1  - Fujii, Masaaki
A1  - Mitrić, Roland
T1  - Deciphering environment effects in peptide bond solvation dynamics by experiment and theory
JF  - Physical Chemistry Chemical Physics
N2  - Most proteins work in aqueous solution and the interaction with water strongly affects their structure and function. However, experimentally the motion of a specific single water molecule is difficult to trace by conventional methods, because they average over the heterogeneous solvation structure of bulk water surrounding the protein. Here, we provide a detailed atomistic picture of the water rearrangement dynamics around the –CONH– peptide linkage in the two model systems formanilide and acetanilide, which simply differ by the presence of a methyl group at the peptide linkage. The combination of picosecond pump–probe time-resolved infrared spectroscopy and molecular dynamics simulations demonstrates that the solvation dynamics at the molecular level is strongly influenced by this small structural difference. The effective timescales for solvent migration triggered by ionization are mainly controlled by the efficiency of the kinetic energy redistribution rather than the shape of the potential energy surface. This approach provides a fundamental understanding of protein hydration and may help to design functional molecules in solution with tailored properties.
KW  - infrared-spectra
KW  - hydration dynamics
KW  - trans-formanilide
KW  - water migration
KW  - protein hydration
Y1  - 2017
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-159647
UR  - http://pubs.rsc.org/en/content/articlelanding/2017/cp/c7cp03992a
N1  - Accepted Version
VL  - 19
IS  - 33
ER  -