Impacts of Ion‐Pairing Effects on Linear and Nonlinear Photophysical Properties of Polymethines Dyes

Simon Pascal (1) , San-Hui Chi , Joseph W Perry , Chantal Andraud , Olivier Maury , S.-H Chi

1 CINaM - Centre Interdisciplinaire de Nanoscience de Marseille

The two-photon absorption (2PA) and photophysics of heptamethine dyes featuring cyanine or dipolar electronic structures has been compared for the first time. The perfectly delocalized cyanine system is classically characterized by a two-photon transition matching the vibronic component of its lower energy absorption band. The dipolar species is generated by ion-pairing with a hard counterion in non-dissociating solvent and displays significant optical properties modifications, including dramatic hypochromic shift of absorption, weaker emission and 2PA matching the lower energy transition, thus revealing symmetry breaking within the polymethine electronic structure. 2

Domaines: Chimie organique; Chimie théorique et/ou physique

Simon Pascal, San-Hui Chi, Joseph W Perry, Chantal Andraud, Olivier Maury, et al.. Impacts of Ion‐Pairing Effects on Linear and Nonlinear Photophysical Properties of Polymethines Dyes. ChemPhysChem, 2020, ⟨10.1002/cphc.202000731⟩. ⟨hal-02999885⟩