A large number of new [Ru II ([9]aneS 3 )(L)Cl] ϩ complexes (where L is a polypyridyl bidentate ligand) were synthesized from the precursor [Ru ([9]aneS 3 )(dmso)Cl 2 ] in the search for new DNA intercalators. The ancillary ligands used have different molecular architectures which include cross bridges, pyridyl units, phenanthroline and diamine derivatives. The related complex [Ru ([9]aneS 3 )(ind)Cl 2 ], containing the monodentate ligand indazole, was also prepared. The diimine complexes [Ru ([9]aneS 3 )(pdi)Cl] ϩ and [Ru ([9]aneS 3 )(phi)Cl] ϩ were prepared in situ from the ligands pda (o-phenylenediamine) and dap (phenanthrene-9,10-diamine), respectively, via Ru assisted amine/imine oxidation. All complexes were characterised through 1 H NMR, IR, UV-Vis and electrospray mass spectrometry. Furthermore, the PF 6 salts of seven [Ru ([9]aneS 3 )(L)Cl] ϩ and [Ru ([9]aneS 3 )(dip)Cl]BF 4 (dip = 4,7-diphenylphenanthroline) have been investigated by X-ray single crystal diffraction. The crystal structures are presented and analysed in terms of the molecular assemblies of the complex cations and anions and the molecular hydrogen bonding interactions. The π-stacking geometric arrangements of the extended aromatic systems dppz (dipyrido[3,2-a : 2Ј,3Ј-c]phenazine) and dip in their metal complexes are also discussed.

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The synthesis and properties of 3 new ligand-bridged bimetallic complexes, 1(2+), 2(2+), and 3(2+), containing [RuCl([9]aneS(3))](+) metal centers are reported. Each complex was bridged by a different ditopic ligand. 1(2+) is bridged by 3,6-bis(2-pyridyl)-1,2,4,5-tetrazine (bptz), while 2(2+) and 3(2+) are bridged by 2,3-bis(2-pyridyl)pyrazine (dpp) and 2,2'-bipyrimidine (bpym), respectively. The Ru([II]) isovalent states of these complexes have been investigated using a variety of techniques. In the case of 3(2+), X-ray crystallography studies show preferential crystallization of an anti form with respect to coordinated chloride ligands (crystal data for [3][Cl(2)].4H(2)O: C(20)H(38)Cl(4)N(4)O(4)Ru(2)S(6), monoclinic, space group P2(1)/a, a = 10.929(14), b = 13.514(17), c = 11.299(16) A, beta = 90.52(1), V = 1669 A(3), Z = 2). UV/vis spectroscopy shows that spectra of these complexes are dominated by intraligand (pi-->pi) and metal-to-ligand Ru(d)-->L(pi) charge transfer transitions. Electrochemical studies reveal that metal-metal interactions are sufficiently intense to generate the Ru(III)/Ru(II) mixed valence [[RuCl([9]aneS(3))(2)](L-L)](3+) state, where L-L = individual bridging ligands. Although the 1(3+), 2(3+), and 3(3+) mixed valence states were EPR silent at room temperature and 77 K, isotropic solution spectra were observed for the electrochemically generated radical cations 1(+), 2(+), and 3(+), with 1(+) displaying well-resolved hyperfine coupling to bridging ligand nitrogens. Using UV/vis/NIR spectroelectrochemistry, we investigated optical properties of the mixed valence complexes. All three showed intervalence charge transfer (IVCT) bands that are much more intense than electrochemical data indicate. Indeed, a comparison of IVCT data for 1(3+) with an analogous structure containing [(NH3)(3)Ru](2+) metal centers shows that the IVCT in the new complex is an order of magnitude more intense. It is concluded that although the new complexes show relatively weak electrostatic interactions, they possess large resonance energies.

The complexes [Ru([9]aneS3)(dppz)Cl]Cl 1 and [Ru([12]aneS4)(dppz)]Cl2 2 ([9]aneS3 = 1,4,7- trithiaciclononane and [12]aneS4 = 1,4,7,10-tetrathiaciclododecane) were synthesised and fully characterised. These complexes belong to a small family of dipyridophenazine complexes with non-polypyridyl ancillary ligands . Interaction studies of these complexes with CT-DNA (UV/Vis titrations, steady-state emission and thermal denaturation) revealed their high affinity for DNA . Intercalation constants determined by UV/Vis titrations are of the same order of magnitude (106) as other dppz metallointercalators, namely [Ru(II)(bpy)2dppz]S2+. Differences between l and2 were identified by steady-state emission and thermal denaturation studies . Emission results are in accordance with structural data, which indicate how geometric distortions and different donor and/or acceptor ligand abilities affect luminescence. The possibility of noncovalent interactions between ancillary ligands and nucleobases by van der Waals contacts and H-bridges is discussed . Furthermore, complex l undergoes aquation under intra-cellular conditions and an equilibrium with the aquated form l' is attained . This behaviour may increase the diversity of available interaction modes.