Gold complexes that could act as antitumor agents have attracted great attention. Heterocyclic compounds and their metal complexes display a broad spectrum of pharmacological properties. The present study reports the preparation and characterization of four novel gold(I) complexes containing tertiary phosphine and new ligands 5-adamantyl-1,3-thiazolidine-2-thione, 3-methyladamantane-1,3,4-oxadiazole-2-thione. Spectroscopic data suggest that gold is coordinated to the exocyclic sulfur atom in all cases, as confirmed by X-ray crystallographic data obtained for complex (1) and supported by quantum-mechanical calculations. The cytotoxicity of the compounds has been evaluated in comparison to cisplatin and auranofin in three different tumor cell lines, colon cancer (CT26WT), metastatic skin melanoma (B16F10), mammary adenocarcinoma (4T1) and kidney normal cell (BHK-21). The gold complexes were more active than their respective free ligands and able to inhibit the thioredoxin reductase (TrxR) enzyme, even in the presence of albumin. Molecular modeling studies were carried out to understand the interaction between the compounds and the TrxR enzyme, considered as a potential target for new compounds in cancer treatment. The docking results show that the adamantane ring is essential to stabilize the ligand-enzyme complex prior the formation of covalent bond with gold center. The structure of the new gold compounds was established on the basis of spectroscopic data, DFT calculations and X-ray diffraction. TrxR inhibition was evaluated and the results correlated with the assays in tumor cells, suggesting the TrxR as possible target for these compounds.

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Eight different coordination polymers (CPs) of Co 2+ and Zn 2+ ions with rigid polycarboxylate ligands (fumaric acid (fum) and 2,5-dihydroxyterephalic acid (dhbdc)) have been synthesized using the same solvents, stoichiometry, and counterion but two different synthetic methods: liquid−liquid diffusion method−method A and pH control method−method B. The synthesis using method A resulted in four novel CPs: trans-Co(dmsoand [trans-Zn(dmso) 2 (H 2 O) 2 (dhbdc)] n (4). Synthesis using method B resulted in one new ([Zn(fum)(OH) 2 ] (6)) and three previously described CPs ([Co 3 (H 2 O) 4 (OH) 2 (fum) 2 ]•2H 2 O (5), [Co 2 (dobdc)] (7), and [Zn 2 (dobdc)] ( 8), where dobdc = 2,5-dioxyterephtalic acid). The new CPs (1−4) were also structurally investigated by single-crystal X-ray diffraction techniques, which showed that all of them form one-dimensional (1D) CPs with linear chain structure: it was evidenced that (1) and ( 3) are isomorphus crystals of ( 2) and ( 4), respectively. The crystal structures of 1−4 were compared with similar 1D, two-and three-dimensional (2D and 3D) CPs reported in the literature. Intraand interchain H-bond networks and coordination (fum, dhbdc, DMSO, water) as well as linkage (fum and dhbdc) isomerism guide the chain configuration (linear or zigzag). It was also demonstrated that the new series of 1D CPs synthesized here (1−4) can work as precursors for CP with higher dimensionality. Our studies showed that the synthetic method plays a crucial role in the crystal growth of coordination polymers.

The first report of the preparation of symmetric and nonsymmetric diaminotruxinic derivatives through the photoredox [2 + 2] cycloadditions of Erlenmeyer azlactones is described, affording the desired compounds in high regio-and diastereocontrol (only head-to-head coupling). Mechanistic studies by DFT suggest that the reaction proceeds through a neutral photocatalytic pathway.

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