| 5,6-(N-heterocycle)[1,10]phenantroline derivatives not only shows the properties ofσdonor /πacceptor of 1,10-phenanthrline, but also extends theπconjugation system of the N-heterocyclic aromatic ring with lower energy. They have been extensively used as ligand in both analytical and preparative coordination chemistry. There will be some differences in properties as merged aromatic ring into 5,6-(N-heterocycle)[1,10]phenantroline. In this paper, two series of 5,6-(N-heterocycle)[1,10]phenantroline ligands and complexes were synthesized and characterized. Their properties were investigated.With 1,10-phenanthroline and aromatic aldehydes as the starting materials, a series of 2,3-diarylpyrazino[2,3-f][1,10]phenantroline ligands were synthesized. The ligands were characterized with 1H-NMR, IR. UV-Vis Absorption and emission properties reveal that the terminal donor plays an important part on the optical activities of the ligands. Furan substituented ligand shows the strongest emission intensity. Thiophene substituented ligand displays the strongest electronic absorption. Benzene substituented ligand presents the weakest electronic absorption and emission intensity.A series of 2-thiopheneimidazo[4,5-f][1,10]phenanthroline derivatives were synthesized and characterized with 1H-NMR, IR and melting-point test. These ligands including 2-thiophenimidazo[4,5-f][1,10]phenanthroline(TIP), 2-(5-nitrothiophen)imidazo [4,5-f][1,10]phenanthroline(5-NTIP), 2-(5-methoxythiophen) imidazo[4,5-f][1,10] phen -anthroline(5-MOTIP), 2-(5-bromothiophen)imidazo[4,5-f][1,10] phenanthroline(5-BTIP) and 2-(4-bromothiophen)imidazo[4,5-f][1,10]phenanthroline (4-BTIP).With 2-thiopheneimidazo[4,5-f][1,10]phenanthroline derivatives as the starting material, their Ru(II) complexes have been synthesized and characterized with IR, element analysis. UV-Vis and emission spectra were collected. The photophysical results reveal that the substituents have important effect on the optical activity of the complexes. Complex with the nitro has the strongest electronic absorption in the MLCT band of the UV-Vis and the weakest emission intensity. Complex with the methoxy has the strongest emission intensity. The DNA-binding properties were investigated by means of spectraphotometrics and viscosity measurements. The results suggest that all these five complexes can bind to CT-DNA with different binding strength. The DNA-binding of complex Ru(bpy)2(5-NTIP)2+ is stronger than other complexes. Ru(bpy)2(5-MOTIP)2+ has the weakest binding affinity among these five complexes. The substituent position of Br atom on ligand makes Ru(bpy)2(4-BTIP)2+ interact stronger with CT-DNA than Ru(bpy)2(5-BTIP)2+. Binding affinity of complexes decrease with the order, Ru(bpy)2(5-NTIP)2+, Ru(bpy)2(4-BTIP)2+, Ru(bpy)2(5-BTIP)2+, Ru(bpy)2(TIP)2+ and Ru(bpy)2(5-MOTIP)2+.
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