Excited-State Proton Transfer of Phenol Cyanine Picolinium Photoacid.

ABSTRACT: Steady-state and time-resolved fluorescence techniques as well as quantum-mechanical calculations were used to study the photophysics and photochemistry of a newly synthesized photoacid-the phenol cyanine picolinium salt. We found that the nonradiative rate constant k _nr of the excited protonated form of the photoacid is larger than that of the excited-state proton transfer (ESPT) to the solvent, k _ESPT. We estimate that the quantum efficiency of the ESPT process is about 0.16. The nonradiative process is explained by a partial trans-cis isomerization reaction, which leads to the formation of a "dark" excited state that can cross to the ground state by nonadiabatic coupling. Moreover, the ESPT process is coupled to the photo-isomerization reaction, as th

SUBMITTER: Pinto da Silva L 

PROVIDER: S-EPMC6641337 | biostudies-literature | 2018 Feb

REPOSITORIES: biostudies-literature