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  - JOUR
A1  - Röhr, Merle I. S.
A1  - Lisinetskaya, Polina G.
A1  - Mitric, Roland
T1  - Excitonic Properties of Ordered Metal Nanocluster Arrays: 2D Silver Clusters at Multiporphyrin Templates
JF  - Journal of Physical Chemistry A
N2  - The design of ordered arrays of metal nanoclusters such as for example 2D cluster organic frameworks might open a new route towards the development of materials with tailored optical properties. Such systems could serve as plasmonically enhanced light-harvesting materials, sensors or catalysts. We present here a theoretical approach for the simulation of the optical properties of ordered arrays of metal clusters that is based on the ab initio parametrized Frenkel exciton model. We demonstrate that small atomically precise silver clusters can be assembled in one- and two-dimensional arrays on suitably designed porphyrin templates exhibiting remarkable optical properties. By employing explicit TDDFT calculations on smaller homologs, we show that the intrinsic optical properties of metal clusters are largely preserved but undergo J- and H-type excitonic coupling that results in controllable splitting of their excited states.
Furthermore, ab initio parameterized Frenkel exciton model calculations allow us to predict an energetic splitting of up to 0.77 eV in extended two-dimensional square arrays and 0.79 eV in tilted square aggregates containing up to 25 cluster-porphyrin subunits.
KW  - Excitons
KW  - Porphyrin arrays
Y1  - 2016
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-159464
UR  - https://pubs.acs.org/doi/10.1021/acs.jpca.6b04243
N1  - Accepted version
VL  - 120
IS  - 26
ER  -