In order to improve the photochromic properties and the fatigue resistance of spiropyran, nitrogen-containing heterocycles were introduced into the indolino ring of the spiropyran through the short carbon chain linkage leading to the synthesis of novel spiropyran compound 1 -(3-N-heterocyc- licpropyl)-3 ,3 -dimethyl-6-nitrospiro[indoline-2,2 (2H)benzopyran] (4a～4f). All compound 4a～4f were characterized by ¹H NMR, ¹³C NMR, IR, and elemental analysis. The photochromic properties of compounds 4a～4f in different solution (ethanol, dichloromathane, and cyclohexane) and polymer film (PMMA and PVB) were studied with the aid of UV absorption spectrometry. The thermal decay process of the representative compound 4a in different solution and polymer film were recorded and analyzed, and the kinetic process were fitted and discussed according to the first-order and second-order kinetics equation. Finally, in comparision with parent spiropyran compound without nitrogen-containing heterocyclic residue, compound 4a possess the better fatigue resistance.

Key words: photochromism, spiropyran, thermal decay, kinetics, fatigue resistance