Berlin 2024 – wissenschaftliches Programm

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 21: Poster II

CPP 21.24: Poster

Dienstag, 19. März 2024, 18:00–20:00, Poster E

Spiropyran/Merocyanine Amphiphile in Organic and Aqueous Media — •Olga Guskova — IPF Dresden, Dresden, Germany

This theoretical study delves into the molecular and photophysical characteristics of an amphiphilic compound containing spiropyran in both organic and aqueous environments. In organic solvents, the system exhibits positive photochromism: under UV radiation, the colorless spiropyran transitions to a vibrant merocyanine isomer. Conversely, in aqueous solutions, a negative photochromism is observed: the orange-red merocyanine form becomes more thermodynamically stable in water, and exposure to UV and visible light results in partial or complete photobleaching. The underlying rationale for this phenomenon is elucidated through density functional theory calculations and classical modeling, including thermodynamic integration. The explanation lies in the molecular properties of merocyanine. Following the ring-opening reaction, this molecule transforms into a zwitterionic form. The presence of three charged groups on the periphery of a flat conjugated backbone promotes the self-assembly of merocyanine molecules in water, leading to the formation of elongated associates with stack-like building blocks. Molecular dynamics simulations of the aqueous solution, with a concentration above the critical micelle concentration, confirm this self-assembly phenomenon. This work is supported by DFG. For more information see: V. Savchenko, N. Lomadze, S. Santer, O. Guskova, Int. J. Mol. Sci. 23 (2022) 11535.

Keywords: spiropyran; merocyanine; photochromism; simulation; DFT