Ruthenium polypyridyl complexes containing the bischelating ligand 2,2′-azobispyridine. Synthesis, characterization and crystal structures

Abstract

Three ruthenium polypyridyl compounds of structural formula [Ru(apy)(tpy)L nÀ ](ClO 4 ) (2Àn) (apy = 2,2 0 -azobispyridine; tpy = 2,2 0 :6 0 ,2 00 -terpyridine; L = Cl, H 2 O, CH 3 CN) (1a-c) were synthesized and crystallized. These complexes were fully characterized by means of 1D and 2D 1 H NMR spectroscopy, as well as mass spectrometry and elemental analysis. Although in theory two isomers are possible, i.e. the one in which the central N atom in tpy is trans to the azo N in apy and the one in which the former is trans to the pyridine N in apy, in all cases only the latter was observed. The molecular structures of the compounds were elucidated by single-crystal X-ray diffraction.

Ruthenium polypyridyl complexes and their modes of interaction with DNA: Is there a correlation between these interactions and the antitumor activity of the compounds?

“…2 has been used. The assignment of the proton signals was based on 2D NMR spectra (data not shown, assignments based on [ 36 ])…”

“…The ligands apy, 2-phenylazopyridine (azpy), and 2-phenylpyridinylmethylene amine (impy) and the metal compounds Ru(tpy)Cl 3 , [Ru(apy)(tpy)Cl](ClO 4 ), [Ru(apy)(tpy)(H 2 O)](ClO 4 ) 2 ·2H 2 O, [Ru(apy)(tpy)(CH 3 CN)](ClO 4 ) 2 , [Ru(azpy)(tpy)Cl]Cl·5H 2 O, and [Ru(impy)(tpy)Cl](ClO 4 ) were synthesized as described in the literature [ 42 , 43 ] and in our earlier reports [ 36 – 38 ].…”

“…The selected series of ruthenium(II) complexes contains the chelating polypyridyl ligand 2,2′:6′,2″-terpyridine (tpy), a bidentate arylazopyridine or aryliminopyridine ligand, and also a labile monodentate ligand L 2 [36–38] (Fig. 1).…”

“…The present investigation focuses on ruthenium polypyridyl coordination compounds which contain only one available coordination site, in an attempt to see whether this is a significant variable in ruthenium complex cytotoxicity. The selected series of ruthenium(II) complexes contains the chelating polypyridyl ligand 2,2′:6′,2″-terpyridine (tpy), a bidentate arylazopyridine or aryliminopyridine ligand, and also a labile monodentate ligand L 2 [ 36 – 38 ] (Fig. 1 ).…”

Role of X-Ray Crystallography in Structural Studies of Pyridyl-Ruthenium Complexes

“…The corresponding complex with 4 ([Ru(4)(bpy)(CO)Cl] + ) is also selectively synthesized by using the above methodology ). Molecular structures of various ruthenium mono-terpyridine complexes of the type [Ru(tpy)(azopyridine)L] n+ (azopyridine = 3, 4, 6; L = Cl, OH 2 , CH 3 CN, NO 2 ) have been determined by X-ray analysis (Corral et al, 2006;Mondal, Walawalkar & Lahili, 2000;Mondal et al, 2001;Ooyama & Asaha, 2005;Oyama, Fujita & Yui, 2008). The asymmetrical nature of azopyridines lead to the possibility of two isomers as shown in Fig.…”