Herein, we report the synthesis and structural characteristics of three tetrazole-containing compounds, 1-benzyl-1H-tetrazole (bntz), 1-benzyl-1H-tetrazol-5-amine (bntza) and 1-(4methoxybenzyl)-1H-tetrazol-5-amine (mbntza) and the corresponding silver(I) complexes of the general formula [Ag(NO3-O)(L-N4)2]n, L = bntz (1), bntza (2) and mbntza (3). Silver(I) complexes 1 -3 and 1-benzyl-1H-tetrazoles have been studied in detail by NMR, IR and UV-Vis spectroscopic methods and the structures of 1 and 2 have been determined by single-crystal Xray diffraction analysis. The results of these analyses revealed a monodentate coordination of the ligands to Ag(I) ion via the N4 tetrazole nitrogen. The antimicrobial potential of silver(I) complexes 1 -3 was evaluated against the broad panel of Gram-positive and Gram-negative bacteria and fungi, displaying their remarkable inhibiting activity with MIC (minimal inhibitory concentration) values in the range 2 -8 and 0.16 -1.25 μg/mL (3.8 -16.3 and 0.31 -2.15 μM), respectively. On the other hand, 1-benzyl-1H-tetrazoles used for the synthesis of the silver(I) complexes were not active against the investigated strains, suggesting that the activity of the complexes originates from the Ag(I) ion exclusively. Moreover, silver(I) complexes 1 -3 have good therapeutic potential, which can be deduced from their moderate cytotoxicity on the human fibroblast cell line MRC5, with IC50 values falling in the range 30 -60 μg/mL (57.7 -103.4 μM).

Silver(i) complexes with pyridine-4,5-dicarboxylates show significant activity against clinical isolates from the milk of a cow diagnosed with mastitis.

Three new silver(I) complexes [Ag(NO3)(tia)(H2O)]n (Ag1), [Ag(CF3SO3)(1,8-naph)]n (Ag2) and [Ag2(1,8-naph)2(H2O)1.2](PF6)2 (Ag3), where tia is thianthrene and 1,8-naph is 1,8-naphthyridine, were synthesized and structurally characterized by different spectroscopic and electrochemical methods and their crystal structures were determined by single-crystal X-ray diffraction analysis. Their antimicrobial potential was evaluated against four bacterial and three Candida species, and the obtained results revealed that these complexes showed significant activity toward the Gram-positive Staphylococcus aureus, Gram-negative Pseudomonas aeruginosa and the investigated Candida species with minimal inhibitory concentration (MIC) values in the range 1.56–7.81 μg/mL. On the other hand, tia and 1,8-naph ligands were not active against the investigated strains, suggesting that their complexation with Ag(I) ion results in the formation of antimicrobial compounds. Moreover, low toxicity of the complexes was detected by in vivo model Caenorhabditis elegans. The interaction of the complexes with calf thymus DNA (ct-DNA) and bovine serum albumin (BSA) was studied to evaluate their binding affinity towards these biomolecules for possible insights into the mode of antimicrobial activity. The binding affinity of Ag1–3 to BSA was higher than that for DNA, indicating that proteins could be more favorable binding sites for these complexes in comparison to the nucleic acids.

Antifungal copper(ii) complexes with pyridine-4,5-dicarboxylate esters show the ability to inhibit the filamentation and biofilm formation of Candida albicans, and efficiently prevent the adhesion of this fungus.

1,2-Bis(4-pyridyl)ethane (bpa) and 1,2-bis(4-pyridyl)ethene (bpe) were used for the synthesis of polynuclear silver(I) complexes, {[Ag(bpa)]NO 3 } n (1), {[Ag(bpa) 2 ]CF 3 SO 3 . H 2 O} n (2) and {[Ag(bpe)]CF 3 SO 3 } n (3). In complexes 1-3, the corresponding nitrogencontaining heterocycle acts as a bridging ligand between two Ag(I) ions. In vitro antimicrobial activity of these complexes, along with the ligands used for their synthesis, was evaluated against the broad panel of Gram-positive and Gram-negative bacteria and fungi. e silver(I) complexes 1-3 showed selectivity towards Candida spp. and Gram-negative Escherichia coli in comparison to the other investigated bacterial strains, effectively inhibiting the growth of four different Candida species with minimal inhibitory concentrations (MICs) between 2.5 and 25 μg/mL and the growth of E. coli, with MIC value being 12.5 μg/mL. Importantly, complex 2 significantly reduced C. albicans filamentation, an essential process for its pathogenesis. Antiproliferative effect on the normal human lung fibroblast cell line MRC-5 was also evaluated with the aim of determining the therapeutic potential of the complexes 1-3. e interactions of these complexes with calf thymus DNA (ctDNA) and bovine serum albumin (BSA) were studied to evaluate their binding activities towards these biomolecules for possible insights on their mode of action.