The invention provides a colour change composition containing an electron donating organic colouring compound, an electron accepting compound and a compound of formula (I): wherein E is an ester linkage OCO or CO2, R is independently selected from an optionally substituted linear or branched alkyl group, alkenyl cycloalkyl group, alkenyl group, alkoxy group, aryl and alkylene aryl group having from 6 to 22 carbon atoms; Y.sub.1 Y.sub.2 X.sub.1 and X2 are independently selected from hydrogen, R, OR and halogen; wherein R is independently selected from an optionally substituted linear or branched alkyl group, alkenyl group, alkoxy group, aryl group and an alkylene aryl group; having from 5 to 22 carbon atoms; r and p each represent and integer from 0 to 3. The compound of formula (I) and compositions of the invention are useful in providing a colour change effect, in memory compositions and visual indicators, particularly in security and healthcare applications. ##STR00001##

The invention provides a colour change composition containing an electron donating organic colouring compound, an electron accepting compound and a compound of formula (I): wherein E is an ester linkage OCO or CO2, R is independently selected from an optionally substituted linear or branched alkyl group, alkenyl cycloalkyl group, alkenyl group, alkoxy group, aryl and alkylene aryl group having from 6 to 22 carbon atoms; Y.sub.1 Y.sub.2 X.sub.1 and X2 are independently selected from hydrogen, R, OR and halogen; wherein R is independently selected from an optionally substituted linear or branched alkyl group, alkenyl group, alkoxy group, aryl group and an alkylene aryl group; having from 5 to 22 carbon atoms; r and p each represent and integer from 0 to 3. The compound of formula (I) and compositions of the invention are useful in providing a colour change effect, in memory compositions and visual indicators, particularly in security and healthcare applications. ##STR00001##