Optical and thermal properties of photochromic fluorinated adamantylidene indolylfulgides

Fluorinated indolylfulgides are a class of photochromic organic compounds with potential applications in the areas of optical memory and optical switches. Absorption spectra, quantum yields, and thermal stability have been measured for a series of fluorinated adamantylidene indolylfulgides. The cyclizable form of the trifluoromethyl-substituted 5-methoxy-1,2-dimethylindolylfulgide displays the longest absorbance maxima reported for the fulgide family. The thermal stability of the cyclizable form of the fluorinated adamantylidene indolylfulgides was greater than that of their corresponding fluorinated isopropylidene analogs, as expected based upon the mechanism of decomposition for isopropylidene analogs. The pentafluoroethyl-substituted adamantylidene indolylfulgide showed only a 27% loss in absorbance after 5 weeks at 80 degreesC in a poly(methylmethacrylate) film. These studies have highlighted the rational design of a thermally stable cyclizable form for fluorinated indolylfulgides. (C) 2002 Elsevier Science B.V. All rights reserved.