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Novel mononuclear silver(I) complexes based on thiocarbamoyl-pyrazoline ligands were synthesized and structurally characterized. Complexes 1 and 2 were prepared in good yields using a sonochemical method. X-ray diffraction studies revealed trigonal coordination geometry for the AgI atom in complex 1 and distorted trigonal pyramidal geometry in complex 2, according to τ4 parameter analysis. Investigation of photophysical properties revealed intense blue-greenish emissions both in solution and in the solid state when excited at 300 nm. This emission was tentatively attributed to mixed (M+X)LCT and IL electronic transitions taking place after ligand metalation, as shown by DFT calculations. Complete characterization of the prepared compounds was also performed, including 1H and 13C NMR experiments, elemental analysis, infrared spectroscopy, absorption/emission studies, and time-resolved luminescence experiments. The synthesized ligands and complexes 1 and 2 were also tested as antibacterial agents against two standard bacterial strains (Staphylococcus aureus ATCC 25923 and Escherichia coli ATCC 25922) and a panel of clinical S. aureus strains with distinct antibiotic-resistance profiles. Antitumor activity was investigated against melanoma cells (B16F10) and mammary carcinoma cells (4T1).

This manuscript describes the synthesis, characterization and structural analysis of copper(II) complexes with pyridoxal-type bidentate ligands, obtained from the condensation between pyridoxal and ortho-halogenated substituted anilines (C1–C5). The complexes C1, C2 and C5 were measured by X-ray single crystal analysis which showed classic and trifurcated hydrogen bonds and interaction as a sigma-hole between the oxygen atoms of the iodine ligand derivative in the complex C5. All compounds were tested as mimetics of superoxide dismutase (SOD), through NBT photoreduction method in aqueous solution of pH 7.8, but the complex C5 showed an expressive IC50 of 0.4 μM. In addition, catecholase-like activity of C1–C5 in the presence of the substrate 3,5-di-tert-butylcatechol and cleavage of plasmid DNA were also evaluated. Again, the best results were associated with the complex C5 containing iodine in the ortho position.

This article presents the synthesis, characterization, evaluation of the mimetic potential of the catalytic activity of the superoxide dismutase enzyme, cytotoxic effects, evaluation of interactions with CT-DNA, and theoretical calculations of copper (II) mononuclear complexes. The C1, C2, and C3 complexes were obtained from the aldolic condensation between aromatic amines (furfurylamine, 2-thiophenethylamine, and 2-thiophenethylamine) and aromatic aldehydes (salicylic aldehyde, ortho-vanillin, and pyridoxal hydrochloride). The compounds were structurally characterized by X-ray diffraction, cyclic voltammetry, FTIR, and ultraviolet/visible spectroscopies. Although the complexes presented coordination modes with identical organic molecules, there were different coordination geometries. In addition, the varied chalcogen substituents revealed an electrochemical potential quite different from the complexes. The synthesized complexes were subjected to NBT photoreduction (nitrotetrazolium blue chloride) to quantify the antioxidant activity, and values of the McCord-Fridovich assay showed that the synthesized complexes have significant superoxide dismutation activity. Moreover, CuII complexes were tested in fluorimetric assays, colorimetric assays to assess cellular metabolic activity, and the dichlorofluorescein diacetate test. Our findings showed that the C2 complex presented the best antioxidant activity with the safest reactive oxygen species generation levels and the least damage to DNA using the evaluated methods. Finally, we evaluated how the synthesized complexes interacted with calf thymus deoxyribonucleic acid by spectroscopic techniques (absorption and emission) and theoretical calculations.

Reaction of fac-[RuCl3(NO)(P–N)] (1) with the triarylphosphines PR3 in MeOH allows for isolation of the monocationic Ru(II) complexes [RuCl2(NO)(P–N)(PR3)]PF6; P–N = o-diphenylphosphino-N,N-dimethylaniline, and R = p-MeO-C6H4 (complex 2), p-Me-C6H4 (3), Ph (4), and p-F-C6H4 (5). The complexes were characterized by elemental analysis, 31P{1H}, 1H NMR and IR spectroscopies, ESI-MS, CV, and X-ray structural data for complexes 3–5. The 31P{1H} spectra display two doublets with 2Jpp values consistent with cis P-atoms. The ESI-MS spectra reveal the molecular ion [RuCl2(NO)(P–N)(PR3)]+ and the fragmentation ions [M−PR3]+, [M−PR3−Cl]+, and [M−PR3−2Cl]+. CV data show a one-electron, quasi-reversible reduction process centred at the Ru–NO unit that depends on the pKa of the PR3. The IR spectra reveal νNO bands for coordinated NO+. A known, empirical inverse correlation between the δP value and the Ru–P bond length of the P–N ligand that exists for a series of cis- and trans-RuX2(L)(P–N)(PR3) complexes (X = Cl or Br), where L is a range of small molecules, is extended with L = NO+ and now covers the respective ranges of about 30–80 ppm and 2.39–2.17 A.

In this work, two novel ruthenium-based compounds containing mercaptothiazolinate ligands were synthesized. A methanol (MeOH) solution containing [RuCl2(PPh3)3], 2-mercaptothiazoline (Hmctz) or 2-mercaptobenzothiazoline (Hmcbtz) (ligand/Ru = 2) and triethylamine (NEt3) was refluxed leading to the formation of neutral complexes with the general formula cis-[Ru(N–S)2(PPh3)2] (N–S = mctz− – complex 1; N–S = mcbtz− – complex 2). We used NMR (1H and 31P{1H}), vibrational spectroscopy (FTIR), and elemental analysis to analyze these two complexes. Cyclic voltammetry revealed that complexes 1 and 2 underwent a reversible one-electron process due to the Ru(III)/Ru(II) pair. Reactivity of the complexes 1 and 2 with dmso leading to the substitution of one PPh3 by dmso was observed (complexes 3 and 4). Complex 1 showed higher antimicrobial activity against Gram (+) and Gram (−) bacteria (Bacillus subtilis and Escherichia coli, respectively). The formation of complex [Ru(mctz)2(dmso)(PPh3)] (3) was faster than complex [Ru(mcbtz)2(dmso)(PPh3)] (4) and this may account for the higher antibacterial activity of complex 1. Single-crystal X-ray diffraction furnished the molecular structures of complex 1 and of the product of its reaction with dmso, [Ru(mctz)2(dmso)(PPh3)] (3).

This work describes the synthesis and structural analysis of the uranium and vanadium complexes [(UO2)(C22H30N6O4)]·MeOH (1) and [(VO)2(O)(C30H36N7O6)]·3MeOH (2) with ligands obtained from the condensation of pyridoxal and triethylenetetramine. The probable mechanism for the formation of imidazoline rings in these complexes is described in some details. Finally, electrochemical and UV–Vis studies of the dinuclear vanadium complex were also carried out in order to determine the variation in the oxidation states of the metallic centers (VO2+/VO3+) in DMSO solution.

The synthesis and the structural characterization of symmetric dimers containing uranium and vanadium atoms provide an outstanding opportunity for the study of hydrogen bonding in supramolecular architectures and unusual interactions. On the search of ligands able to coordinate itself to two metal ions simultaneously, we have synthesized the Schiff bases bis((3-hydroxy-5-(hydroxymethyl)-2-methylpyridin-4-yl)methylene) oxalohydrazide (H6Pyr2oxdihyd) and bis((3-hydroxy-5-(hydroxymethyl)-2-methylpyridin-4-yl)methylene) succinohydrazide (H10pyr2sucdihyd), efficient symmetric ligands with an inversion center, obtained through the reaction of pyridoxine/pyridoxal hydrochloride with oxalyl dihydrazide and succinic dihydrazide. Their reactions and the products obtained with the oxofilic uranyl(VI) and vanadyl(V) cations were discussed, as well as computational methods were used as complementary tools in the study of intra and intermolecular bonds.

Synthesis of three novel inorganic complexes (Zn(II), Pd(II), and Pt(II) – [Zn(H2L)](NO3)2, [Pd(L)], and [Pt(L)], respectively) based on 2,6-diformylpyridine-bis-(4-phenyl) thiosemicarbazone (H2L) was obtained under reflux medium, yielded in the range of 67% and 86%. Characterization of each compound was done via X-ray diffraction and spectroscopic methods. Structural analysis revealed the formation of complexes with pentagonal and quadratic bipyramidal geometry. Electronic absorption spectra for the ligand and inorganic complexes exhibited π → π* and n → π* transitions in the UV region, however, [Pd(L)] and [Pt(L)] showed other less energetic bands attributed to ligand-to-metal charge transfer (LMCT). The interaction between each compound and two macromolecules: calf-thymus DNA (CT-DNA) and bovine serum albumin (BSA) was conducted by spectroscopic techniques combined to molecular docking calculation. For CT-DNA interaction, [Zn(H2L)](NO3)2 is the weakest intercalate compound and the increasing order of Kb values follows [Zn(H2L)](NO3)2

In this work, the formation and characterisation of two new isostructural metal–organochalcogen clusters from simple starting materials was investigated. A sonochemical synthesis was performed in a one-pot procedure without the isolation of synthetic intermediates. This methodology offers a new approach to prepare cluster compounds, and this experiment led to the formation of [(PhTe)12Hg8(S)X2(Py)2]·Py (X = Br, I; Py = Pyridine) in good yield. The X-ray analyses reveal that the framework of the clusters contains a similar [Hg8(μ4-S)Te12] core as the central unit. The sulphur atom present in the core of both structures has a tetrahedral coordination geometry achieved by four S–Hg(II) bonds. The complete characterisation of the synthesised materials also includes elemental analyses, IR spectroscopy and UV–Vis absorption data.

UO2(NO3)2·6H2O and VO(acac)2 react with 2-(2′-hydroxylphenyl)benzoxazole (Hpbx) in methanol to give [UO2(pbx)2(CH3OH)] (1) and [VO(pbx)2] (2). Complex 1 shows a distorted pentagonal bipyrimidal geometry, characteristic for the coordination number 7. Reciprocal OH⋯O interactions between neighbored molecules hold 1 in a pseudo-dimeric association with an inversion center. Complex 2 achieves a distorted octahedral geometry and the molecules “stack” along the b axis through secondary interactions. The molecule heaping is wholly linear, with Vn′−O(1)n′⋯V x′ angles of 180°. Luminescence properties of Hpbx, 1 and 2 are discussed.

Two new compounds of Cu(II) of stoichiometry CuCl4(polyamineH2) containing the polyamines (PA): spermidine or spermine were prepared. Their synthesis, spectroscopic and structural characterization are herein described. The obtained complex with spermidine was characterized by elemental and thermogravimetric analysis, electronic and infrared spectroscopy. In the case of the compound with spermine, crystals were obtained. So, beside all other techniques the compound was also characterized by single crystal X-ray diffractometry. In both cases the species [CuCl4]2− is present and displays a similar polymeric structure. The X-ray, infrared and electronic spectra are herein discussed based on structural peculiarities of the compounds.