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TYPE I AND TYPE II SENSITIZERS BASED ON ROSE BENGAL ONIUM SALTS *
Author(s) -
Linden Shwn Meei,
Neckers D. C.
Publication year - 1988
Publication title -
photochemistry and photobiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.818
H-Index - 131
eISSN - 1751-1097
pISSN - 0031-8655
DOI - 10.1111/j.1751-1097.1988.tb08842.x
Subject(s) - onium , rose bengal , sulfonium , chemistry , photochemistry , solvent , salt (chemistry) , singlet oxygen , singlet state , ion , inorganic chemistry , organic chemistry , oxygen , excited state , nuclear physics , physics
— New Rose Bengal oniurn salts containing one or two iodonium, sulfonium, phosphonium, and pyrylium ions have been prepared as part of a program to develop sensitizers which can function as Type I radical photoinitiators and Type II energy transfer donors depending on experimental conditions. The absorption spectra of the onium salts in different solvents indicate an equilibrium between tight and loose ion pairs which depends on the solvent polarity, the cation and concentration. Typical Rose Bengal photochemistry requires the structure be that of the loose ion pair in the solvent of choice. Similar factors also influence bleaching behavior, and bleaching is the result of electron transfer processes. The quantum yields of singlet oxygen production from the onium salts in polar solvents are similar to that of the parent, Rose Bengal disodium salt.