Patent ID: 7399639

Claim:
A compound comprising a first fluorophore, a second fluorophore and a cleavable linker covalently linking the first fluorophore and the second fluorophore, wherein the fluorescence of the first and second fluorophores are substantially quenched by one another before the cleavable linker is cleaved, and wherein the first fluorophore is represented by the following structure: or a tautomer thereof, wherein, independently for each occurrence: Y is O, S, Se, NR, or C(CH 3 ) 2 , wherein R is an alkyl; Q is O, S or Se; Z is V, QH, or QU′ wherein U′ is a hydroxyl-protecting group; W and W′ are each independently K or V; K is hydrogen, halogen, linear or branched alkyl, alkenyl, linear or branched aminoalkyl, linear or branched acylamino, linear or branched acyloxy, linear or branched alkoxycarbonyl, linear or branched alkoxy, linear or branched alkylaryl, linear or branched hyrdoxyalkyl, linear or branched thioalkyl, acyl, aryloxy, arylalkoxy, alkynyl, cyano, sulihydryl, carbamoyl, trifluoromethyl, lower alkylthio, lower alkylamino, nitro, amine, hydroxyl, carbonyl, formyl or sulfonyl; L is the cleavable linker covalently bonded to either the 5 or 6 position of the indicated aromatic ring; L comprises an ester; and V is a chemical moiety comprising at least one Lewis base capable of coordinating to a metal ion; and wherein one or more fluorescence properties of the first fluorophore change measurably upon coordination of said Lewis base to a metal ion.