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Published on: December 21, 2017
Impact of Ion-Pairing Effects on Linear and Nonlinear Photophysical Properties of Polymethine Dyes*
Simon Pascal1,2, San-Hui Chi3, Joseph W Perry3
1Laboratoire de Chimie, Univ. Lyon, ENS Lyon, CNRS, Université Lyon 1, 46 Allée d'Italie, 69364, Lyon, France.
Abstract:
The two-photon absorption (2PA) and photophysics of heptamethine dyes featuring cyanine or dipolar electronic structures have 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 a non-dissociating solvent and displays significant modifications oft he optical properties, including a significant hypochromic shift of absorption, weaker emission and 2PA matching the lower energy transition, thus revealing symmetry breaking within the polymethine electronic structure.
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