Mixed-ligand aroylhydrazone complexes of molybdenum: Synthesis, structure and biological activity

Comprehensive Insights into Medicinal Research on Imidazole-Based Supramolecular Complexes

The electron-rich five-membered aromatic aza-heterocyclic imidazole, which contains two nitrogen atoms, is an important functional fragment widely present in a large number of biomolecules and medicinal drugs; its unique structure is beneficial to easily bind with various inorganic or organic ions and molecules through noncovalent interactions to form a variety of supramolecular complexes with broad medicinal potential, which is being paid an increasing amount of attention regarding more and more contributions to imidazole-based supramolecular complexes for possible medicinal application. This work gives systematical and comprehensive insights into medicinal research on imidazole-based supramolecular complexes, including anticancer, antibacterial, antifungal, antiparasitic, antidiabetic, antihypertensive, and anti-inflammatory aspects as well as ion receptors, imaging agents, and pathologic probes. The new trend of the foreseeable research in the near future toward imidazole-based supramolecular medicinal chemistry is also prospected. It is hoped that this work provides beneficial help for the rational design of imidazole-based drug molecules and supramolecular medicinal agents and more effective diagnostic agents and pathological probes.

Synthesis, Characterization, and Antibacterial Evaluation of Heteroleptic Oxytetracycline-Salicylaldehyde Complexes

A new series of mixed ligand complexes of Cd(II) and Mo(V) were successfully synthesized by refluxing the mixture solution of oxytetracycline hydrochloride (OTC.HCl) with an aqueous and alcoholic solution of metal (M = Cd(II) and Mo(V)) salts and an alcoholic solution of salicylaldehyde (Sal). The complexes were characterized by modern analytical and spectral methods such as elemental microanalysis, pH, conductivity, surface tension, viscosity, melting point, and spectral methods such as FT-IR, NMR, electronic absorption, SEM, and mass spectrometry. Conductivity measurements of the complexes revealed their electrolytic nature. The kinetic and thermal stabilities were investigated using thermogravimetric and differential thermal analysis techniques. Thermodynamic and kinetic parameters such as E∗, ΔH∗, ΔS∗, and ΔG∗ were calculated from TG curves using the Coats–Redfern method. Geometry optimization of the proposed structure of the complexes was achieved by running MM2 calculations in a Gaussian-supported CS ChemOffice 3D Pro.12.0 version software. The final optimized geometrical energies for respective Cd-OTC/Sal and Mo-OTC/Sal complexes were found to be 923.1740 and 899.3184 kcal/mol. The electronic absorption spectral study revealed a tetrahedral geometry for the Cd-OTC/Sal complex and octahedral geometry for the Mo-OTC/Sal complex. The antibacterial sensitivity of the complexes was evaluated against three bacterial pathogens such as S. aureus, E. coli, and P. mirabilis using the modified Kirby–Bauer paper disc diffusion method. The antibacterial study revealed significant growth inhibitory action of the complexes.

The reaction of oxidorhenium(v) with dipodal and tripodal aroylhydrazines: formation of dinuclear and trinuclear aroylhydrazone-bridged rhenium(v) complexes

The chemistry of aroylhydrazines has been attracting attention mainly due to the residual functional group, –CONH–NH₂, which has important effects on hydrophilicity and has the potential to provide special interaction sites for targeting molecules.

Discrete and polymeric ensembles based on dinuclear molybdenum(vi) building blocks with adaptive carbohydrazide ligands: from the design to catalytic epoxidation

Discrete and polymeric ensembles based on dimolybdenum(vi) units with adaptive carbohydrazide ligands are described. The polymeric complexes are efficient catalysts for cyclooctene epoxidation under eco-friendly conditions.

Polynuclear zinc(II) complexes of thiosemicarbazone: Synthesis, X-ray structure and biological evaluation

Two new dimeric Zn(II) ([{ZnL¹(DMSO₂)}₂]·DMSO (1), [{ZnL²Cl}₂] (2)) and a novel tetrameric Zn(II) complex ([(Zn₂L³)₂(μ-OAc)₂(μ₃-O)₂] (3)), where H₂L¹ = 4-(p-methoxyphenyl) thiosemicarbazone of o-hydroxynapthaldehyde, HL² = 4-(p-methoxyphenyl)thiosemicarbazone of benzoyl pyridine and H₂L³ = 4-(p-chlorophenyl)thiosemicarbazone of o-vanillin are reported. Ligands and their complexes were characterized by spectroscopic and single crystal X-ray diffraction techniques. In addition, the complexes exhibited good binding affinity towards HSA (10¹² M^-1), which is supported by their ability to quench the tryptophan fluorescence emission spectra of HSA. The complexes were also screened for their DNA binding propensity through UV-vis absorption titration, circular dichroism and fluorescence spectral studies. Results show that they effectively interact with CT-DNA through an intercalative mode of binding, with binding constants ranging from 10³ to 10⁴ M^-1. Among the three complexes 1 has the highest binding affinity towards CT-DNA. Further, the phosphatase activity was evaluated using bis(2,4-dinitrophenyl)phosphate (BDNPP) as substrate, however, the complexes did not yield any measurable catalytic activity. Nevertheless the complexes showed significant cytotoxic potential against HeLa and HT-29 cancer cell lines that was assessed through MTT assay and DAPI staining. Remarkably, complex 1 showed better activity than cisplatin against HT-29 cell line.

New mononuclear and binuclear oxomolybdenum(V) complexes containing NN chelator: Syntheses, DFT calculations, interaction with BSA protein and in vitro cytotoxic activity

A neutral bidentate ligand 2-(3-methyl-5-phenyl pyrazol-1-yl) benzthiazole (L) has been synthesized by refluxing equimolar proportions of 2-hydrazino benzthiazole and benzoyl acetone in ethanol. The ligand acts in a NN donor fashion and forms stable mononuclear, MoOX₃L [L = Ligand, X = Cl (1), Br (2)] and binuclear Mo₂O₄X₂L₂ [L = Ligand, X = Cl (3), Br (4)] complexes with molybdenum(V). The ligand and complexes are thoroughly characterized by elemental analyses, IR, UV-Vis spectroscopy, EPR study, magnetic susceptibility, thermogravimetry and cyclic voltammetry. Magnetic moment measurements reveal that the mononuclear complexes are paramagnetic while the binuclear complexes are diamagnetic in nature. EPR studies also confirm the presence of a mononuclear Mo(V) moiety in the complexes. Relevant Density Functional Theory (DFT) calculations have been carried out to determine the structures of the synthesized compounds. The binding mode and mechanism of interaction of the synthesized compounds with bovine serum albumin (BSA) were studied by concentration dependent absorption and fluorescence titration experiments. The ligand and complexes 1-4 are screened for their potential in vitro anticancer activities against three different human cancer cell lines, namely, cervix adenocarcinoma epithelial cells (HeLa), renal carcinoma cells (SK-RC-45) and breast adenocarcinoma cells (MCF-7). The oxomolybdenum(V) complexes are found to exhibit higher anticancer potency towards the cancer cells than the free ligand. Also, structure activity relationship (SAR) studies of this new series of oxomolybdenum(V) complexes indicate that the anticancer activity is to some extent dependent on the electronic effects of the halogen atom coordinated to the molybdenum centre.

Synthesis, structure and cytotoxicity of a series of Dioxidomolybdenum(VI) complexes featuring Salan ligands

Seven hexacoordinated cis-dioxidomolybdenum(VI) complexes [MoO₂L^1-7] (1-7) derived from various tetradentate diamino bis(phenolato) "salan" ligands, N,N'-dimethyl-N,N'-bis-(2-hydroxy-3-X-5-Y-6-Z-benzyl)-1,2-diaminoethane {(X=Br, Y=Me, Z=H (H₂L¹); X=Me, YCl, Z=H (H₂L²); X=ⁱPr, Y=Cl, Z=Me (H₂L³)} and N,N'-bis-(2-hydroxy-3-X-5-Y-6-Z-benzyl)-1,2-diaminopropane {(X=Y=^tBu, Z=H (H₂L⁴); X=Y=Me, Z=H (H₂L⁵); X=ⁱPr, YCl, Z=Me (H₂L⁶); X=Y=Br, Z=H (H₂L⁷)} containing O-N donor atoms, have been isolated and structurally characterized. The formation of cis-dioxidomolybdenum(VI) complexes was confirmed by elemental analysis, IR, UV-vis and NMR spectroscopy, ESI-MS and cyclic voltammetry. X-ray crystallography showed the O₂N₂ donor set to define an octahedral geometry in each case. The complexes (1-7) were tested for their in vitro antiproliferative activity against HT-29 and HeLa cancer cell line. IC₅₀ values of the complexes in HT-29 follow the order 6<7<<1<2<5<<3<4 while the order was 6<7<5<1<<3<4<2 in HeLa cells. Some of the complexes proved to be as active as the clinical referred drugs, and the greater potency of 6 and 7 (IC₅₀ values of 6 are 2.62 and 10.74μM and that of 7 is 11.79 and 30.48μM in HT-29 and HeLa cells, respectively) may be dependent on the substituents in the salan ligand environment coordinated to the metal.

New polymeric, dimeric and mononuclear dioxidomolybdenum(vi) complexes with an ONO donor ligand: crystal structures, DFT calculations, catalytic performance and protein binding study of the ligand

Catalytic activity and BSA binding is reported.

Crystal structure of aqua-[(E)-N'-(5-bromo-2-oxido-benzyl-idene-κO)benzohydrazidato-κ(2) O,N']dioxidomolybdenum(VI) di-methyl-formamide monosolvate

The title compound, [Mo(C14H9BrN2O2)O2(H2O)]·C3H7NO, has a distorted octa-hedral geometry around the Mo atom, with the two terminal oxide groups lying cis to each other. The two aromatic rings present in the mol-ecule are almost coplanar, forming a dihedral angle of 1.4 (2)°. The five-membered ring involving the metal atom is puckered, with an amplitude Q = 0.358 (2) Å and ϕ = 204.1 (6)°. In the crystal, pairs of inversion-related mol-ecules are linked by O-H⋯N hydrogen bonds. An O-H⋯O hydrogen bond connects the water ligand to the di-methyl-formamide solvent mol-ecule. The crystal packing also features π-π [centroid-centroid distance of 3.688 (2) Å] and C-H⋯O inter-actions.

Synthesis, X-ray structure and in vitro cytotoxicity studies of Cu(i/ii) complexes of thiosemicarbazone: special emphasis on their interactions with DNA

The interactions of four Cu-TSC complexes with DNA & their cytotoxicity studies against the HeLa cell have been reported.

Effect of N-based additive on the optimization of liquid phase oxidation of bicyclic, cyclic and aromatic alcohols catalyzed by dioxidomolybdenum(vi) and oxidoperoxidomolybdenum(vi) complexes

Catalytic potentials of [Mo^VIO₂]²⁺ and [Mo^VIO(O₂)]²⁺ complexes with dibasic tridentate ONO donor ligands for the oxidation of bicyclic, cyclic and aromatic alcohols in the presence of NEt₃ are reported.

Supramolecular frameworks of binuclear dioxomolybdenum(vi) complexes with ONS donor ligands using 4,4′-azopyridine as a pillar: crystal structure, DFT calculations and biological study

4,4′-Azpy is used as linker forming pillared dioxoMo(vi) complexes first time, biological activities are reported.

Microwave assisted synthesis, characterization and biocidal activities of some new chelates of carbazole derived Schiff bases of cadmium and tin metals

This study is planned to report the advancement of green microwave approach in the fabrication of a new series of biologically potent (N^X, where X=O/S) donor Schiff bases and their cadmium(II) and tin(II) complexes. The ligands and their metal complexes have been characterized in terms of elemental analysis, molar ionic conductance, magnetic moment and spectral (IR, UV-Vis, NMR ((1)H, (119)Sn), FAB-mass, thermal and XRD) data. The data revealed that the ligands coordinated to the metal center via nitrogen and oxygen/sulfur atoms and form an octahedral arrangement of the ligands around central metal atom. All compounds were evaluated for their in vitro antimicrobial activities against two pathogenic bacteria Bacillus subtilis and Escherichia coli and two fungi Aspergillus niger and Aspergillus flavus by standard disc diffusion method. The discs were stored in an incubator at 37°C. The compounds were dissolved in DMF at 500 and 1000 ppm concentrations for screening biocidal activity. The compounds were dissolved in DMF to get the 100 and 200 ppm concentration of test solutions for screening fungicidal activity. The inhibition zone around each disc was measured (in mm) after 24 h and 96 h for biocidal and fungicidal activities respectively.

Synthesis of Oxovanadium(IV) Complexes with Tetraaza Coordinating Ligands

Oxovanadium(IV) complexes of the type [VO(mac)]SO4(where mac = tetraaza macrocyclic ligands derived by condensation of thenil with 1,4-diaminobenzene or 3,4-diaminopyridine and their reaction withβ-diketones) have been prepared using vanadyl ion as kinetic template. The prepared macrocyclic complexes were characterized by elemental analyses, molar conductance, magnetic moments, and infrared, electronic, and electron spin resonance data. From the spectroscopic studies, five-coordinate square-pyramidal geometry for the VO2+complexes have been proposed wherein derived ligands act as tetradentate chelating agents.