The DNA cleavage activity of copper complexes of phenanthroline has been increased by the use of “2‐Clip‐Phen” and “3‐Clip‐Phen” ligands containing two phenanthroline entities linked by a serinol bridge. In order to optimize DNA cleavage activity, two series of new Clip‐Phen ligands (L) with two phenanthroline residues linked through their C‐2 or C‐3 carbon atoms by different bridges have been synthesized. The physicochemical properties and the DNA cleavage activities of the corresponding (Clip‐Phen)copper complexes were investigated in the presence of a reductant and air. X‐ray analyses of single crystals showed that the cupric complexes of Clip‐Phen were able adopt dimeric double‐helical geometries with L2Cu2 stoichiometries in the solid state. These complexes adopt different geometries and stoichiometries in solution, with monomeric LCu species predominant. The compounds with a bridge connected at C‐2 are less active as DNA cleavage agents than complexes with the bridge at the C‐3 positions. Copper complexes with a bridge containing three methylene units appear to give the best results in DNA cleavage experiments. This activity is increased in the case of 3‐Clip‐Phen·CuCl2 by the presence of the primary amine function of the serinol bridge. This amine function is probably coordinated to the copper atom in the case of 2‐Clip‐Phen·CuCl2, decreasing the reactivity toward DNA. (© Wiley‐VCH Verlag GmbH & Co KGaA, 69451 Weinheim, Germany, 2003)

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Due to its cost, environmental benefits, and safety advantages, water has become more and more important as a solvent for catalytic reactions and constitutes the best environment for biomedical applications. Therefore, water-soluble and water-stable metal complexes containing strong σ-donor ligands such as N-heterocyclic carbenes (NHCs) are of great interest in modern coordination chemistry. In this paper we present the successful preparation of two new dinuclear gold(I)–bis(NHC) complexes in water, by applying the Ag–NHC transfer route. This green synthetic strategy is valuable for gold(I) compounds involving N-functionalized neutral and dianionic bis(NHC) ligands. These two water-soluble compounds were analyzed by spectroscopic methods and by X-ray diffraction. Furthermore, ab initio and DFT calculations on the corresponding dinuclear gold complexes illustrate the important influence of the electrostatic environment of the dinuclear entity on the aurophilic interactions and help to understand the molecular arrangement presented in this paper.

Three heterobimetallic gold(I)–ruthenium(II) complexes containing heteroditopic bipyridine–N-heterocyclic carbene (NHC) ligands were synthesized and fully characterized by spectroscopic methods and in one case by single-crystal X-ray diffraction. In addition, the in vitro cytotoxic, antileishmanial, and antimalarial activities of these new heterobimetallic complexes were assessed. Moreover, the photophysical properties of two compounds have been used to localize them in tumor cells by confocal microscopy.

A series of new mononuclear cationic or neutral gold(I) complexes containing quinoline functionalized N-heterocyclic carbene(s) (NHC(s)) were synthesized and fully characterized by spectroscopic methods. The X-ray structures of two key compounds are presented. Proligands and their corresponding gold(I) complexes together with previously described silver(I) and gold(I) bis(NHC-quinoline) and gold(I) bis(NHC-methylbipyridine) complexes were evaluated in vitro towards Leishmania infantum. In parallel, the in vitro cytotoxicity of these molecules was assessed on the murine macrophages J774A.1. All gold(I) compounds show potent antileishmanial activity against L. infantum promastigotes and three of them are also efficient against L. infantum intracellular amastigotes. Structure-activity and toxicity relationships enables to evidence a lead-compound (6) displaying both a high activity and a good selectivity index.

We report the synthesis of Au(I) and Au(III) complexes, involving alcohol functionalized bis(N-heterocyclic carbene) ligands. Two short reaction pathways lead to the diimidazolium precursors, namely 1,1'-(2,6-pyridinediyl)bis[3-(2-hydroxyethyl)-1H-imidazol-3-ium]diiodide (), 3,3'(methanediyl)bis[1-(2-hydroxy-2-methylpropyl)-1H-imidazol-3-ium]dibromide () and 3,3'-(1,3-propanediyl)bis[1-(2-hydroxy-2-methylpropyl)-1H-imidazol-3-ium]bis(4-methylbenzenesulfonate) (), in which the two azolium rings are bridged by a rigid pyridine unit or an aliphatic chain (C1 or C3). The Au(I) complexes [AuI(Lpy)]2(2+)[PF6-]2 () and [AuI(LC1)]2(2+)[PF6-]2 () were obtained by direct metallation of the salts and , respectively, in the presence of sodium acetate with Au(SMe(2))Cl, followed by an anionic metathesis in the presence of KPF6. The trimethylene compound [AuI(LC3)]2(2+)[PF6-]2 () was prepared by transmetallation between the related precursor [AgI(LC3)]2(2+)[PF6-]2 () and Au(SMe2)Cl. The Au(III) complexes, [AuIII(Lpy)Br2]2(2+)[PF6-]2 (), [AuIII(LC1)Br2]2(2+)[PF6-]2 () and [AuIII(LC3)Br2]2(2+)[PF6-]2 () were generated by oxidation of the corresponding Au(I) species with an excess of elemental bromine. Complexes , [AuI(LC1)]2(2+)[Br-]2 () and have been characterized by single-crystal X-ray diffraction analyses. The electrochemical and luminescence properties of the Au(I) and Au(III) compounds have been studied.

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