title: Ruthenium(III) chloride complex with a tridentate bis(arylimino)pyridine ligand: synthesis, spectra, X-ray structure, 9-ethylguanine binding pattern, and in vitro cytotoxicity.
abstract: The synthetic, spectroscopic, structural, and biological studies of a bis(arylimino)pyridine Ru(III) chloride compound containing the ligand, 2,6-bis(2,4,6-trimethylphenyliminomethyl)pyridine are reported. The bis(arylimino)pyridine ligand, with three donor nitrogen atoms, was synthesized by condensation of 2,6-pyridinedicarboxaldehyde with 2,4,6-trimethylaniline. The Ru(III) complex, with formula [RuCl 3(L1)](H 2O) (RuL1), where L1 = 2,6-bis(2,4,6-trimethylphenyliminomethyl)pyridine, was structurally determined on the basis of analytical and spectroscopic (IR, UV-vis, ESI-MS) studies. A straightforward strategy to fully characterize the paramagnetic compound using advanced (1)H NMR is reported. This new complex is a prototype for a series of new anticancer Ru(III) and Ru(II) compounds with improved cytostatic properties; likely to be modified in a desirable manner due to the relatively facile ligand modification of the bis(imino)pyridines and their molecular architecture. The present Ru(III) complex is the first example of this family of Ru(III)/Ru(II) anticancer compounds with the aimed physicochemical characteristics. Although the ligand itself is moderately active in selected cell lines (EVSA-T and MCF-7), the activity of the [Ru(L1)Cl 3] complex has increased significantly for a broad range of cancer cell lines tested in vitro (IC 50 values = 11 approximately 17 microM). Reaction of the RuL1 species with the DNA model base 9-ethylguanine (9EtGua) was found to produce in a redox reaction the species trans-[Ru(II)(L1)(9EtGua) 2(H 2O)](ClO 4) 2 (abbreviated as RuL1-9EtGua), which was studied in solution and also in the solid state, by X-ray crystallography. The structure comprises the as yet unknown trans-bis(purine)Ru(II) unit.
authors.affiliation: Leiden Institute of Chemistry, Gorlaeus Laboratories, Leiden University, P.O. Box 9502, 2300 RA Leiden, The Netherlands.
authors.forename: Ariadna
authors.initials: A
authors.lastname: Garza-Ortiz
authors.forename: Palanisamy Uma
authors.initials: PU
authors.lastname: Maheswari
authors.forename: Maxime
authors.initials: M
authors.lastname: Siegler
authors.forename: Anthony L
authors.initials: AL
authors.lastname: Spek
authors.forename: Jan
authors.initials: J
authors.lastname: Reedijk
mesh_terms: D000042:Absorption; D000970:Antineoplastic Agents / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology* / Q000633:toxicity; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D018360:Crystallography, X-Ray; D006801:Humans; D007097:Imines / Q000737:chemistry*; D011725:Pyridines / Q000737:chemistry*; D017975:Ruthenium Compounds / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology* / Q000633:toxicity; D013057:Spectrum Analysis
chemical_list: C531370:2,6-bis(2,4,6-trimethylphenyliminomethyl)pyridine; D000970:Antineoplastic Agents; D007097:Imines; D011725:Pyridines; D017975:Ruthenium Compounds; C038365:ruthenium chloride