Fluorescent indicators for calcium metal ion detection

A compound with the chemical structure (I), or a salt thereof:

• wherein:
• R is H, an ammonium salt, a metal cation, an alkyl having 1-10 carbons, —Ac, or —CH2OAc;
• R1-R11 are independently H, a halogen, an alkyl, an aryl or a heteroaryl;
• and
• R12-R15 are independently H, an alkyl, a halogen, carboxy, carboxyalkylester, carboxyamide, an acyloxymethylcarbonyl, an alkoxy, an aryloxy, a thiol, an alkylthiol, an arylthiol, an azido, a nitro, a nitroso, a cyano, an amino, a hydroxy, a phosphonyl, a sulfonyl, a sulfonamide, a carbonyl, a boronyl, an aryl, a heteroaryl, a heterocycle or a fluorophore moiety;
• or any two of R1-R11 are cyclically linked together, where R12-R15 are independently H, an alkyl, a halogen, carboxy, carboxyalkylester, carboxyamide, an acyloxymethylcarbonyl, an alkoxy, an aryloxy, a thiol, an alkylthiol, an arylthiol, an azido, a nitro, a nitroso, a cyano, an amino, a hydroxy, a phosphonyl, a sulfonyl, a sulfonamide, a carbonyl, a boronyl, an aryl, a heteroaryl, a heterocycle or a fluorophore moiety;
• or R10 is cyclically linked to R12, where R1-R9 and R11 are independently H, a halogen, an alkyl, an aryl or a heteroaryl;
• R13-R15 are independently H, an alkyl, a halogen, carboxy, carboxyalkylester, carboxyamide, an acyloxymethylcarbonyl, an alkoxy, an aryloxy, a thiol, an alkylthiol, an arylthiol, an azido, a nitro, a nitroso, a cyano, an amino, a hydroxy, a phosphonyl, a sulfonyl, a sulfonamide, a carbonyl, a boronyl, an aryl, a heteroaryl, a heterocycle or a fluorophore moiety;
• or R11 is cyclically linked to R12, where R1-R10 are independently H, a halogen, an alkyl, an aryl or a heteroaryl:
• R13-R15 are independently H, an alkyl, a halogen, carboxy, carboxyalkylester, carboxyamide, an acyloxymethylcarbonyl, an alkoxy, an aryloxy, a thiol, an alkylthiol, an arylthiol, an azido, a nitro, a nitroso, a cyano, an amino, a hydroxy, a phosphonyl, a sulfonyl, a sulfonamide, a carbonyl, a boronyl, an aryl, a heteroaryl, a heterocycle or a fluorophore moiety;
• or R8 is cyclically linked to R15, where R1-R7 and R9-R11 are independently H, a halogen, an alkyl, an aryl or a heteroaryl;
• R12-R14 are independently H, an alkyl, a halogen, carboxy, carboxyalkylester, carboxyamide, an acyloxymethylcarbonyl, an alkoxy, an aryloxy, a thiol, an alkylthiol, an arylthiol, an azido, a nitro, a nitroso, a cyano, an amino, a hydroxy, a phosphonyl, a sulfonyl, a sulfonamide, a carbonyl, a boronyl, an aryl, a heteroaryl, a heterocycle or a fluorophore moiety;
• or R9 is cyclically linked to R15, where R1-R8 and R10-R11 are independently H, a halogen, an alkyl, an aryl or a heteroaryl;
• R12-R14 are independently H, an alkyl, a halogen, carboxy, carboxyalkylester, carboxyamide, an acyloxymethylcarbonyl, an alkoxy, an aryloxy, a thiol, an alkylthiol, an arylthiol, an azido, a nitro, a nitroso, a cyano, an amino, a hydroxy, a phosphonyl, a sulfonyl, a sulfonamide, a carbonyl, a boronyl, an aryl, a heteroaryl, a heterocycle or a fluorophore moiety.