Patent ID: 7777055

Claim:
A compound reversibly convertible between a ring-open isomer (I) and a ring-closed isomer (II): wherein: each R 1 is independently selected from the group consisting of H and a halogen; each R 2 is independently H, a halogen, or both R 2 when taken together form CH═CH, or R 2 is CH═CH and forms part of a polymer backbone; each R 3 is independently selected from the group consisting of H, a halogen, CO 2 Y (Y═H, Na, alkyl, aryl), and (X═N,O,S); R 4 is aryl; and each R 5 is independently selected from the group consisting of H, alkyl and aryl, and wherein compound is convertible from said ring-open isomer (I) to said ring-closed isomer (II) under photochemical conditions and from said ring-closed isomer (II) to said ring-open isomer (I) under electrochemical conditions.