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The development of small molecules that can bind and recognize DNA with sequence- or stereo-specificity under physiological conditions has been attracting a great interest in chemistry and biochemistry. Here, spectroscopic characterization and gel electrophoresis methods have been utilized to investigate the DNA binding and recognition by a variety of binuclear transition metal complexes. The result indicate that the structures and charges of binuclear transition metal complexes, compositions of coordination spheres, central metal ions and their coordination unsaturation, and separations between two central metal atoms can exert significant effects on the DNA binding and recognition. If there are not intercalative ligands into DNA base pairs or kinetically substitutable ligands by DNA phosphate groups within coordination sphere, the coordination saturation and compact binuclear transition metal complexes weaker bind to DNA than the coordination unsaturation and extended ones to DNA. Since the different transtiometal ions exhibit different affinities to DNA phosphate oxygen atoms, the binding interactions between their binuclear complexes and DNA are controlled by the affinity. He binuclear complexes with one or more negative charges lead to a consequence that they can not efficient associate with DNA, because DNA phosphodiester backbone is negatively charged. Whenthe separations between two central transition metal atoms is more than the distance between two DNA base pairs, the binuclear complexes could bind and recognize the DNA sequence with two or more base pairs. The protonated and positively charged ligands can strengthen the DNA binding and recognition by these binuclear metal complexes. Based on such DNA binding and recognition principles, the binuclear zinc complex designed in the study preferentially bind and recognize the following DNA sequence on pBR322 DNA with binding constant K.
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