Dresden 2014 – wissenschaftliches Programm
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 9: Crystallization, Nucleation and Self Assembly II
CPP 9.3: Vortrag
Montag, 31. März 2014, 15:45–16:00, ZEU 260
Modelling the structure of tubular J-aggregates using MD-simulations and MD-based calculations of exciton spectra — •Jörg Megow1, Stefan Kirstein1, Merle Röhr2, Marcel Schmidt am Busch3, Roland Mitrić2, Thomas Renger3, Jürgen P. Rabe1, and Volkhard May1 — 1Humboldt-Universität zu Berlin, Deutschland — 2Julius-Maximilians-Universität, Würzburg, Deutschland — 3Johannes Kepler Universität, Linz, Österreich
Tubular J-aggregates composed of amphiphilic cyanine dyes have been studied in [1,2]. Two different approaches were used to build a molecular model of the structure: First, a theoretical model based on absorption spectra and on orientations of transition dipoles was translated into real arrangements of molecules [1]. Second, molecules were packed to reproduce best a structure model based on high resolution cryo-TEM [2]. For the first time now, molecular dynamics (MD) simulations of the aggregates in solution together with MD-based calculations of optical spectra are utilized to study the structure of the system. MD simulations of both structure models show that the model of [1] is instable, while the model that is consistent with [2] is stable during MD simulation. Based on the simulations, Frenkel exciton spectra for both structure models have been computed. It will be shown that a detailed calculation of the energy transfer coupling, including screening effects, allows for a reasonably good description of the absorption spectrum also for the second structure model.
[1] D. Eisele, et al., Nature Chemistry 4, 655-662 (2012)
[2] H. v. Berlepsch et al., Chem. Phys. 285, 27-34 (2011)