A compound represented by general formula (IA) or a salt thereof useful as a fluorescent probe for zinc: wherein R.sup.1 and R.sup.2 represent a hydrogen atom or a group represented by formula (A), wherein X.sup.1, X.sup.2, X.sup.3, and X.sup.4 represent a hydrogen atom, an alkyl group, a 2-pyridylmethyl group, or a protective group for an amino group, and m and n represent 0 or 1 provided that R.sup.1 and R.sup.2 do not simultaneously represent hydrogen atoms; R.sup.3 and R.sup.4 represent a hydrogen atom or a halogen atom; and R.sup.5 and R.sup.6 represent a hydrogen atom, an alkylcarbonyl group, or an alkylcarbonyloxymethyl group, and R.sup.7 represents a hydrogen atom or an alkyl group. ##STR00001##