Positive and negative fluorescent imaging induced by naphthalimide polymers

Abstract

Two novel polymers with naphthalimide pendant groups have been prepared. In poly(2-methylacrylic acid 2-[6-(4-methylpiperazin-1-yl)-1,3-dioxo-2,3-dihydro-1H-benzo[de]isoquinolin-2-yl]ethyl ester-co-methyl methacrylate) (copolymer 1), an alkylated tertiary amine acts as an electron donor and quenches the fluorescence of the naphthalimide fluorophore via the photo-induced electron transfer (PET) process. Protonation of the alkylated tertiary amine by an acid generated by a photoacid generator (PAG) can switch off the PET path and the fluorescence of the naphthalimide fluorophore would be recovered and enhanced. For poly(2-methylacrylic acid 2-[6-(4-methylpiperazin-1-yl)-1,3-dioxo-2,3-dihydro-1H-benzo[de]isoquinolin-2-yl]ethyl ester) (polymer 3), protonation both of the aromatic amine and the alkylated amine by the acids generated from may result in significant fluorescence quenching and alter the fluorophore. When protonation processes occur, the fluorescence enhancement (×2) of copolymer 1 or the fluorescence quenching (×15) of polymer 3 would be applied to generate positive or negative fluorescent patterned images on their net films.