Organic fatigue-resistant photochromic imaging materials

Photochromism in the fulgides described in the paper depends upon conrotatory photocyclisation on exposure to ultraviolet light. The reverse process occurs on irradiation of the resulting coloured compounds with visible light. The reactions, being concerted, do not involve reactive intermediates and the photochromic systems show a very high resistance to fatigue processes as well as complete thermal stability at ambient temperatures. Linear response, high sensitivity, low destructive readout and retention of all these characteristics when in plastic matrix make these systems well suited for optical data storage.