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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 46: Poster II
CPP 46.32: Poster
Donnerstag, 12. März 2026, 09:30–11:30, P5
Photoresponsive Interfacial Behavior of Hybrid Photosensitizer-Surfactant Mixtures — •Phat Tan Pham1, Julius Gemen2, Frank Glorius2, and Björn Braunschweig1 — 1Universität Münster, Institut für Physikalische Chemie, Corrensstr. 28/30, 48149 Münster — 2University of Münster, Organisch-Chemisches Institut, Corrensstraße 40, 48149 Münster
Fluid interfaces that adapt to external triggers such as light or temperature are of great interest for driving changes in soft matter systems like foams and emulsions. Arylazopyrazoles (AAPs), as photo-responsive surfactants, can control surface tension and molecular organization at air-water interfaces through E/Z photoisomerization. However, light-induced switching of AAP derivatives is typically limited to UV and green light. To overcome this, we combined AAP with the water-soluble photosensitizer resazurin (Rez) and achieved pronounced interfacial changes under 625 nm red-light irradiation. By tuning the AAP/Rez molar ratio, we further introduced history-dependent, quasi-adaptive changes in surface tension and molecular structure. The latter was examined in situ with surface tensiometry and vibrational sum-frequency generation (SFG) when the samples where irradiated at 365, 520, or 625 nm. We propose that red-light activation occurs at the interface, through photoexcited Rez moieties at 625 nm and subsequent intersystem crossing to adjacent interfacial AAP molecules. These results demonstrate a new strategy to extend the optical control of photo-responsive surfactants into the red-light region.
Keywords: Photosensitizer; AAP; Photo-responsive; Fluid interfaces; Soft matter