Synthesis of IR-sensitive photoswitchable molecules: photochromic 9?- styrylquinolinedihydroindolizines

Abstract

New mono- (5a–t, w) and biphotochromic (5u, v) 9′-styrylquinolinespirodihydroindolizines (DHIs) with IR-absorbing colored forms (4) were prepared. The conformation and configuration of these new DHIs were investigated by NMR studies and the structure was proved by x-ray analysis. The kinetics of the fast cyclizing process of betaine 4 to DHI 5 takes place in the millisecond range and were studied by flash photolysis. The absorption bands of the betaines 4 were recorded at low temperature by FT-UV/VIS/near-IR spectroscopy. Large solvent effects on the absorption maxima of betaines 4 were observed. Copyright © 2000 John Wiley & Sons, Ltd.