Patent ID: 8557989

Claim:
A compound of the formula: wherein, R and R 1 are the same or different and each can be selected from: 2,2′-bipyridyl, 4,4′-disubstituted-2,2′-bipyridyl, 5-5′-disubstituted-2,2′-bipyridyl, 1,10-phenanthrolinyl, 4,7-disubstituted-1,10-phenanthrolinyl, 5,6-disubstituted-1,10-phenanthrolinyl, or N,N′-dimethyl 2,2′-biimidazole wherein each substituent is a methyl, ethyl, or phenyl group, and where the R and R′ groups are coordinated to Os through their nitrogen atoms; R 3 is H, CH 3 or C 2 H 5 ; L is (CH 2 ) i Q, wherein i is an integer 1-10 and Q is O or NR 3 ; B is a group comprising a ligand capable of binding to a specific analyte binding partner; Z is chlorine or bromine; X is a counter ion; y is selected to provide a neutral salt; and m is 1 or 2.