Synthesis of a polyphenol with a mesoionic 6-oxo-1,6-dihydropyrimidin-3-ium-4-olate as pendant group and its photochemical behavior

摘要

This study deals with synthesis of a polyphenol bearing photosensitive groups, and its photochemical behavior upon UV radiation. Mesoionic 5-(4-hydroxybenzyl)-6-oxo-1,2,3-triphenyl-1,6-dihydropyrimidin-3-ium-4-ola te was prepared by condensation of 4-benzyloxybenzylmalonic acid with N,N'-diphenylbenzamidine using dicyclohexylcarbodiimide as condensing agent, followed by deprotection of the benzyl group. The monomer was polymerized by an iron-salen complex to give a polymer with a mesoionic 6-oxo-1,6-dihydropyrimidin-3-ium-4-olate moiety as the pendant group. Spin coated polymer films were prepared and characterized. It was shown by IR spectroscopy that irradiation with UV light converted the mesoionic structure to a bis(beta-lactam) structure. Waveguide spectroscopy showed a large decrease in the film thickness without refractive index changes during irradiation. [References: 24]