A 2,2"-bipyridine ligand for incorporation into oligodeoxynucleotides: synthesis, stability and fluorescence properties of ruthenium-DNA complexes.

A non-nucleoside linker based upon the ligand 2,2'-bipyridine and ethylene glycol is prepared and placed into the backbone of a number of oligonucleo-tides. The bipyridine ligand is reacted with cis -dichloro bis(2,2'-bipyridyl) Ru(II) to generate the relatively substitutionally inert complex based upon the well-characterized tris -2,2'-bipyridyl Ru(II). The ruthenium-containing DNA complexes exhibited UV and fluorescence characteristics that are consistent with those previously observed for simple tris -2,2'-bipyridyl Ru(II) complexes. Oligonucleotides containing the ruthenium complex will form both DNA duplexes and triplexes with stabilities that are slightly better than those formed from simple tethered oligonucleotide probes in which the two hybridizing sequences are tethered by simple tri(ethylene glycol) or hexa(ethylene glycol) linkers.