Patent ID: 8288544

Claim:
A compound of the formula: wherein R and R 1 are the same or different and each can be selected from: 2,2â€²-bipyridyl, 4,4â€²-disubstituted-2,2â€²-bipyridyl, 5-5â€²-disubstituted-2,2â€²-bipyridyl, 1,10-phenanthrolinyl, 4,7-disubstituted-1,10-phenanthrolinyl, 5,6-disubstituted-1,10-phenanthrolinyl, or N,Nâ€²-dimethyl 2,2â€²-biimidazole, wherein each substituent is a methyl, ethyl, or phenyl group, and where the R and R 1 groups are coordinated to osmium through their nitrogen atoms; R 2 is hydrogen, methyl, or ethyl; B is a group comprising a ligand capable of binding to a specific analyte binding partner; Z is chloro or bromo; X is a counter ion; y is selected to provide a neutral salt; and m is 2 to 4.