Various interaction modes between a group of six ruthenium polypyridyl complexes and DNA have been studied using a number of spectroscopic techniques. Five mononuclear species were selected with formula [Ru(tpy)L1L2](2−n)+, and one closely related dinuclear cation of formula [{Ru(apy)(tpy)}2{μ-H2N(CH2)6NH2}]4+. The ligand tpy is 2,2′:6′,2″-terpyridine and the ligand L1 is a bidentate ligand, namely, apy (2,2′-azobispyridine), 2-phenylazopyridine, or 2-phenylpyridinylmethylene amine. The ligand L2 is a labile monodentate ligand, being Cl−, H2O, or CH3CN. All six species containing a labile L2 were found to be able to coordinate to the DNA model base 9-ethylguanine by 1H NMR and mass spectrometry. The dinuclear cationic species, which has no positions available for coordination to a DNA base, was studied for comparison purposes. The interactions between a selection of four representative complexes and calf-thymus DNA were studied by circular and linear dichroism. To explore a possible relation between DNA-binding ability and toxicity, all compounds were screened for anticancer activity in a variety of cancer cell lines, showing in some cases an activity which is comparable to that of cisplatin. Comparison of the details of the compound structures, their DNA binding, and their toxicity allows the exploration of structure–activity relationships that might be used to guide optimization of the activity of agents of this class of compounds.Electronic supplementary materialThe online version of this article (doi:10.1007/s00775-008-0460-x) contains supplementary material, which is available to authorized users.

ICP reduction after a change in body position is significantly greater in patients with free CSF flow through the craniospinal junction than in those with Chiari malformation, indicating the difficulty or impossibility of CSF displacement into the spinal canal in the latter.

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.