Berlin 2018 – wissenschaftliches Programm
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 11: Responsive and Adaptive Systems
CPP 11.1: Vortrag
Montag, 12. März 2018, 11:15–11:30, C 230
Light-responsive azobenzene star with a flat core — •Markus Koch1, Marina Saphiannikova1, Svetlana Santer2, and Olga Guskova1 — 1Institute Theory of Polymers, IPF Dresden, Germany — 2Institute of Physics and Astronomy, University of Potsdam
This study focuses on comparing physical properties of photoisomers of an azobenzene star with benzene-1,3,5-tricarboxamide core. Three azobenzene arms of the molecule undergo a reversible trans-cis isomerisation upon UV-vis light illumination giving rise to multiple states from the planar all-trans one, via two mixed states to the kinked all-cis isomer. To characterize the light-triggered switching of solvophilicity/solvophobicity of the star, the difference in solvation free energy is calculated for the transfer of an azobenzene star from its gas phase to implicit or explicit solvents. From the analysis of two contributions to the free energy of hydration, the non-polar van der Waals and the electrostatic terms, calculated using soft LJ and Coulomb potentials [1] we conclude that isomerization state largely determines the polarity of the molecule and the solute-solvent electrostatic interactions. This convertible hydrophilicity/hydrophobicity together with re-adjustable occupied volume and the surface area accessible to water, explains the physics of the self-assembly/disassembly of the azobenzene star with a flat core triggered by light.
This work was supported by DFG (Project No GU 1510/3-1 and SA 1657/13-1).
[1] M. Koch et al. J. Phys. Chem. B 2017, 121, 8854.