Synthesis and photochemical behavior of 2-(N-acridonyl)ethyl methacrylate and its polymer

Abstract

A polymerizable photosensitizer, 2-(N-acridonyl)ethyl methacrylate (AEMA), containing both aromatic ketone and aromatic tertiary amine moieties in the same molecule, was prepared by reaction of N-hydroxyethyl acridone (HEA) and methacryloyl chloride in the presence of triethylamine (TEA). HEA was obtained by reaction of acridone with ethylene carbonate. The photochemical behavior including photoinitiation and fluorescence properties of AEMA and its polymer P(AEMA) were studied. It was found that the photoinitiation efficiency of monomeric AEMA is lower than that of its polymer for the photopolymerization of acrylonitrile (AN) in DMF. By the kinetic study and the analysis of recorded electron spin resonance spectra of the photoinitiation systems of AEMA or AEMA-dimethylaminoethyl methacrylate (DMAEMA) trapped by 2-methyl-2-nitritopropane (MNP), the mechanism is deduced to be similar to that of the benzophenone-TEA system. The recorded fluorescence spectra show that AEMA and P(AEMA) possess a strong fluorescence emission peak at 410 and 439 nm, respectively. The concentration self-quenching effect was observed with maximum intensities at a concentration of 8.6 X 10 -5 mol/L in DMF for both AEMA and P(AEMA). Even though AEMA has a tertiary amino group and an electron-deficient acrylic double bond in the same molecule, it did not display structural self-quenching effect as we reported previously. This may be due to the two benzene rings in acridone that lessen the electron-donating ability of the N atom. The fluorescence quenching of AEMA and P(AEMA) by electron-donating and electron-accepting compounds was also investigated.