Synthesis and photochromic properties of ferrocenyl-substituted benzo- anddibenzochromenes

The synthesis, photochromic behaviour, photodegradation parameters and fluo rescence spectra of a range of benzo- and dibenzochromenes substituted by a ferrocenyl group in the 2-position have been investigated. The ferrocenyl group leads to two absorption bands in the visible spectrum bf the photomer ocyanine Species, in contrast to the single band observed with correspondin g phenyl substituted derivatives. It also increases the thermal rate of ble aching of the photomerocyanine.