Abstract: A compound represented by the following general formula (II): wherein R21 represents hydrogen atom or one to four monovalent substituents substituting on the benzene ring, and when R21 represents two or more substituents, the substituents may be the same or different; R22, R24, R25, and R27 independently represent hydrogen atom, or a monovalent substituent; R23 represents —OH or —N(R28)(R29) (wherein R28 and R29 independently represent an alkyl group which may be substituted); R26 represents —N(R30)(R31) (wherein R30 and R31 independently represent an alkyl group which may be substituted); n represents an integer of 1 to 3; and Y represents —S— or —O—, which is useful for selective measurement of hypochlorite ion.

Abstract: A compound represented by the following general formula (I): [R1 represents hydrogen atom, or 1 to 4 monovalent substituents; R2, R4, R5, and R7 represent hydrogen atom, or a monovalent substituent; R3 represents ?O or ?N+(R8)(R9).M? (R8 and R9 represent an alkyl group, and M? represents a counter ion); R6 represents —OH or —N(R10)(R11) (R10 and R11 represent an alkyl group); n represents an integer of 1 to 3; and X represents —SH or —OH], which is useful for selective measurement of hypochlorite ion and the like.

Abstract: A fluorescent probe which is represented by the following formula (I): (wherein, R1 and R2 represent hydrogen atom, or a substituent for trapping proton, a metal ion, or an active oxygen species, or the like; R3 represents a monovalent substituent; R4 and R5 represent hydrogen atom or a halogen atom; R6 represents hydrogen atom, an alkylcarbonyl group, or an alkylcarbonyloxymethyl group, provided that a combination of R1, R2, and R3 provides (1) substantially high electron density of the benzene ring to which said groups bind, so that the compound represented by the formula (I) is substantially no fluorescent before the trapping of proton, or the like, and (2) substantially reduced electron density of the benzene ring to which said groups bind, so that a compound after the trapping, which is derived from the compound represented by the formula (I) is substantially highly fluorescent after the trapping of proton or the like). A fluorescent probe having an excellent fluorescence property is provided.

Abstract: A fluorescent probe which is represented by the following formula (I): (wherein, R1 and R2 represent hydrogen atom, or a substituent for trapping proton, a metal ion, or an active oxygen species, or the like; R3 represents a monovalent substituent; R4 and R5 represent hydrogen atom or a halogen atom; R6 represents hydrogen atom, an alkylcarbonyl group, or an alkylcarbonyloxymethyl group, provided that a combination of R1, R2, and R3 provides (1) substantially high electron density of the benzene ring to which said groups bind, so that the compound represented by the formula (I) is substantially no fluorescent before the trapping of proton, or the like, and (2) substantially reduced electron density of the benzene ring to which said groups bind, so that a compound after the trapping, which is derived from the compound represented by the formula (I) is substantially highly fluorescent after the trapping of proton or the like). A fluorescent probe having an excellent fluorescence property is provided.