Microwave-assisted synthesis of novel spirooxazines and their photochromic behaviors in polymer matrices

A series of 1,3,3-trimethylspiro[2H]-indol-2,3′-[3H]-naphtho[2,1-b][1,4]oxazine derivatives(spirooxazine) weresynthesized using the microwave method. Their photochromic behaviors in styrene-butadiene-styrene copolymer (SBS), polycarbonate (PC), and polymethylmethacrylate (PMMA) were investigated. Results show thatthe colored form of spirooxazine is more stable in polar PMMA and cause a blue shift in the absorption spectrum of merocyanine. Furthermore, a broad thermal relaxation time range was obtained, from 129s to 1724s(in PMMA, at 20°C) througha structuralmodification of6′-heterocycle and 9′-acyloxy. These results present a new strategy for designing photochromic molecules that feature different and acceptable relaxation times.