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MO: Fachverband Molekülphysik

MO 13: Poster – Ultrafast Electronic Dynamics

MO 13.5: Poster

Tuesday, March 3, 2026, 17:00–19:00, Philo 1. OG

Unraveling Strong Coupling and Excitonic Dipole Reorganization in Macrocyclic Squaraine Dimers via 2DES Anisotropy — •Yi Xu¹, Jonathan Herpich², Christoph Lambert², and Tobias Brixner¹ — ¹Institut für Physikalische und Theoretische Chemie, Universität Würzburg, Am Hubland, 97074 Würzburg, Germany — ²Institut für Organische Chemie, Universität Würzburg, Am Hubland 97074 Würzburg

A macrocyclic squaraine (MSQ) consists of two covalently linked squaraine chromophores forming a torus-shaped π-conjugated ring that exhibits H-aggregate-like interactions. When two such macro-cycles associate to form an MSQ dimer, additional inter-macrocycle coupling arises, giving rise to new excitonic states with mixed H- and J-aggregate character, as revealed by UV-vis-NIR and CD spectra.

To probe how local squaraine transition dipole moments reorganize in the MSQ dimer, we employ polarization-resolved 2DES anisotropy. The anisotropy dynamics reveal a clear reorganization of transition dipole moments (TDMs), suggesting the emergence of delocalized excitonic dipoles spanning both macrocycles. Ongoing analysis aims to quantify the relative dipole orientation and the extent of electronic delocalization across the dimer.

These findings offer a microscopic view of dipole reorganization in hierarchical chromophore assemblies and demonstrate that 2DES anisotropy is a powerful tool for disentangling inter-macrocycle coupling and aggregate character in complex π-conjugated systems.

Keywords: macrocyclic squaraine; two-dimensional electronic spectroscopy; anisotropy; polarization dependence; electronic delocalization