TICT and ULM models for the radiationless deactivation of rhodamines

Abstract

The formation of a twisted intramolecular charge transfer state (TICT model) and changing of the amino group from a planar to a pyramidal structure (ULM model) are applied to explain the radiationless deactivation of rhodamines with different molecular structures in water and in ethanol. Both theories offer valid interpretation for the photophysics of rhodamines if intramolecular xanthene-carboxyphenyl and specific solutesolvent interactions are considered. © 1992 Indian Academy of Sciences.