ubstituted, provided that at least one of ArMC1 and ArMC2 has at least one substituent selected from ???COOH and ???COSH, as a substituent; each of RMC1 and RMC2 which are independent of each other, is a hydrogen atom, an alkyl group which may be substituted, or an alkenyl group which may be substituted; YMC represents the following group: YMC1 represents a bivalent organic connecting group, cMC i