The development of novel and operationally simple synthetic routes to carbene‐metal‐amido (CMA) complexes of copper, silver and gold relevant for photonic applications are reported. A mild base and sustainable solvents allow all reactions to be conducted in air and at room temperature, leading to high yields of the targeted compounds even on multigram scales. The effect of various mild bases on the N−H metallation was studied in silico and experimentally, while a mechanochemical, solvent‐free synthetic approach was also developed. Our photophysical studies on [M(NHC)(Cbz)] (Cbz=carbazolyl) indicate that the occurrence of fluorescent or phosphorescent states is determined primarily by the metal, providing control over the excited state properties. Consequently, we demonstrate the potential of the new CMAs beyond luminescence applications by employing a selected CMA as a photocatalyst. The exemplified synthetic ease is expected to accelerate the applications of CMAs in photocatalysis and materials chemistry.
A series of new palladium allyl complexes bearing purine-based carbenes derived from caffeine, theophylline and theobromine have been prepared and characterized by NMR spectroscopy, and elemental analysis and in two cases by single crystal X-ray diffraction. The cytotoxic and proapoptotic activities of compounds have been determined in vitro on human ovarian cancer A2780 and SKOV-3 cell lines. These experiments have shown that the palladium-allyl fragment induces a general cytotoxicity, but the choice of the supporting ligands is of paramount importance for achieving the best results. In particular complexes 4c, 4d and 5d exhibit a higher antiproliferative effect (IC50: 0.09, 0.81 and 0.85 μM respectively) than cisplatin (IC50: 1.5 μM) on A2780 cells, and 4d (IC50: 1.7 μM vs. 5.94 μM) on SKOV-3 cell line. Moreover in many cases it has been proved that the cytotoxicity of our complexes is associated with the induction of apoptosis.
1 October 2019 in Journal of Organometallic Chemistry
The introduction of biologically relevant organic moieties in the coordination sphere of transition metal complexes has recently become a well-established strategy to increase the selectivity and biocompatibility of metallodrugs. In this review, the major advances achieved in this area of research in the last three years are described in detail. Particular attention is given to the metal complexes bearing the main biomolecules of life: carbohydrates, lipids, nucleotides, proteins and vitamins. Each paragraph summarizes the synthetic strategy employed to obtain the complexes of interest as well as the most interesting biological results obtained with these potential metallodrugs. Moreover, the structure–activity relationships observed by the different research groups are described and discussed, with the goal of suggesting to the reader the ligand/metal centre combinations that provide the most promising results in the fight against cancer. Some of the compounds examined in this review as well as other bioconjugated metal complexes published in recent decades exhibit interesting selectivity towards cancer cells over normal ones and a specific mode of action. These latter aspects are the basis of what is commonly known as anticancer target therapy.