Synthesis, characterization, and electrochemical studies of Co(II, III) dithiocarbamate complexes

Antiproliferative activity of Fe(II), Co(II), Ni(II), Cu(II), and Zn(II) complexes of dithiocarbamate: synthesis, structural characterization, and thermal studies

Five new metal complexes of Fe(II) (1), Co(II) (2), Ni(II) (3), Cu(II) (4), and Zn(II) (5), derived from an N-cyclohexyl N-(3,4-dimethoxybenzyl) dithiocarbamate ligand, have been successfully synthesized and fully characterized by different analytical techniques i.e. elemental analyses, FT-IR, UV-Vis, 1H & 13C NMR, and HRMS. Furthermore, complexes 4 and 5 have been characterized by the SC-XRD technique. Complex 4 adopts a distorted square planar geometry around the Cu(II) center while complex 5 adopts a distorted tetrahedral geometry around the Zn(II) center. In addition, an eight-membered symmetric chair-like metallacycle ring containing two Zn(II) centers has also been found in complex 5. XRD data also show that complexes 4 and 5 are stabilized by various weak intermolecular hydrogen bonding interactions. The course of the thermal degradation of metal complexes 1-5 has been examined by TG-DTA data which revealed that metal sulphide formed as the final residue. Complexes 1-5 demonstrated concentration-dependent cytotoxicity and growth inhibition of DL tumor cells. Among the compounds, complexes 1, 4, and 5 showed significant cytotoxicity and induced a loss in the viability of DL cells. Therapy with complexes 1, 4, and 5 protects DL tumor-bearing animals from exacerbation of the disease, increases lifespan, and significantly improves the histopathological parameters of the vascularized organ, including preventing metastasis. Overall cytotoxicity assay results indicate that all complexes have remarkable cytotoxic potential in comparison with the free ligand.

Antiviral Potential of Selected N-Methyl-N-phenyl Dithiocarbamate Complexes against Human Immunodeficiency Virus (HIV)

Despite the use of highly active antiretroviral therapy approved by the United States Food and Drug Administration (FDA) for the treatment of human immunodeficiency virus (HIV) infection, HIV remains a public health concern due to the inability of the treatment to eradicate the virus. In this study, N-methyl-N-phenyl dithiocarbamate complexes of indium(III), bismuth(III), antimony(III), silver(I), and copper(II) were synthesized. The complexes were characterized by thermal gravimetric analysis (TGA), differential scanning calorimetry (DSC), and Fourier transform infrared spectroscopy (FTIR). The N-methyl-N-phenyl dithiocarbamate complexes were then evaluated for their antiviral effects against HIV-1 subtypes A (Q168), B (QHO.168), and C (CAP210 and ZM53). The results showed that the copper(II)-bis (N-methyl-N-phenyl dithiocarbamate) complex had a neutralization efficiency of 94% for CAP210, 54% for ZM53, 45% for Q168, and 63% for QHO.168. The silver(I)-bis (N-methyl-N-phenyl dithiocarbamate) complex showed minimal neutralization efficiency against HIV, while indium(III) and antimony(III) N-methyl-N-phenyl dithiocarbamate complexes had no antiviral activity against HIV-1. The findings revealed that copper(II)-bis (N-methyl-N-phenyl dithiocarbamate), with further improvement, could be explored as an alternative entry inhibitor for HIV.

Diaryl dithiocarbamates: synthesis, oxidation to thiuram disulfides, Co(III) complexes [Co(S2CNAr2)3] and their use as single source precursors to CoS2

Air and moisture stable diaryl dithiocarbamate salts, Ar₂NCS₂Li, result from addition of CS₂ to Ar₂NLi, the latter being formed upon deprotonation of diarylamines by ⁿBuLi. Oxidation with K₃[Fe(CN)₆] affords the analogous thiuram disulfides, (Ar₂NCS₂)₂, two examples of which (Ar = p-C₆H₄X; X = Me, OMe) have been crystallographically characterised. The interconversion of dithiocarbamate and thiuram disulfides has also been probed electrochemically and compared with that established for the widely-utilised diethyl system. While oxidation reactions are generally clean and high yielding, for Ph(2-naphthyl)NCS₂Li an ortho-cyclisation product, 3-phenylnaphtho[2,1-d]thiazole-2(3H)-thione, is also formed, resulting from a competitive intramolecular free-radical cyclisation. To demonstrate the coordinating ability of diaryl dithiocarbamates, a small series of Co(III) complexes have been prepared, with two examples, [Co{S₂CN(p-tolyl)₂}₃] and [Co{S₂CNPh(m-tolyl)}₃] being crystallographically characterised. Solvothermal decomposition of [Co{S₂CN(p-tolyl)₂}₃] in oleylamine generates phase pure CoS₂ nanospheres in an unexpected phase-selective manner.

Dithiocarbamate Complexes as Single Source Precursors to Nanoscale Binary, Ternary and Quaternary Metal Sulfides

Nanodimensional metal sulfides are a developing class of low-cost materials with potential applications in areas as wide-ranging as energy storage, electrocatalysis, and imaging. An attractive synthetic strategy, which allows careful control over stoichiometry, is the single source precursor (SSP) approach in which well-defined molecular species containing preformed metal-sulfur bonds are heated to decomposition, either in the vapor or solution phase, resulting in facile loss of organics and formation of nanodimensional metal sulfides. By careful control of the precursor, the decomposition environment and addition of surfactants, this approach affords a range of nanocrystalline materials from a library of precursors. Dithiocarbamates (DTCs) are monoanionic chelating ligands that have been known for over a century and find applications in agriculture, medicine, and materials science. They are easily prepared from nontoxic secondary and primary amines and form stable complexes with all elements. Since pioneering work in the late 1980s, the use of DTC complexes as SSPs to a wide range of binary, ternary, and multinary sulfides has been extensively documented. This review maps these developments, from the formation of thin films, often comprised of embedded nanocrystals, to quantum dots coated with organic ligands or shelled by other metal sulfides that show high photoluminescence quantum yields, and a range of other nanomaterials in which both the phase and morphology of the nanocrystals can be engineered, allowing fine-tuning of technologically important physical properties, thus opening up a myriad of potential applications.

Morphological Studies, Photocatalytic Activity, and Electrochemistry of Platinum Disulfide Nanoparticles from Bis(morpholinyl-4-carbodithioato)-platinum(II)

Bis(morpholinyl-4-carbodithioato)-platinum(II) was synthesized and characterized using spectroscopic techniques and single-crystal X-ray crystallography. The Pt(II) complex crystallized in a monoclinic space group P2₁/n with a Pt(II) ion located on an inversion center coordinated two morpholinyl dithiocarbamate ligands that are coplanar to form a slightly distorted square planar geometry around the Pt(II) ion. The complex was thermolyzed at 120, 180, and 240 °C to prepare PtS₂ nanoparticles. Powder X-ray diffraction patterns confirmed the hexagonal crystalline phase for the as-prepared PtS₂ nanoparticles irrespective of thermolysis temperature. Bead-like shaped PtS₂-120 nanoparticles with a particle size in the range of 12.46-64.97 nm were formed at 120 °C, while PtS₂-180 prepared at 180 °C is quasi-spherical in shape with particles in the range of 24.30-46.87 nm. The PtS₂-240 obtained at 240 °C is spherical with particles in the range of 11.45-46.85 nm. The broad emission maxima of the as-prepared PtS₂ nanoparticles are ascribed to the particles' broad size distributions. The photocatalytic degradation of methylene blue by the PtS₂ nanoparticles shows a maximum efficiency of 87% for PtS₂-240 after 360 min. The effects of photocatalytic dosage, irradiation time, pH medium, and scavengers were also evaluated. Cyclic voltammetry of the PtS₂ nanoparticles showed a reversible redox reaction, while the electrochemistry of the as-prepared PtS₂ indicates that the electron transfer process is diffusion-controlled.