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C18H21N3O2, triclinic, P1̅ (no. 2), a = 8.5155(4) Å, b = 10.6415(4) Å, c = 19.0732(10) Å, α = 80.918(4)°, β = 89.689(4)°, γ = 80.666(4)°, V = 1683.74(14) Å3, Z = 4, Rgt(F) = 0.055, wRref(F2) = 0.133, T = 100 K. [ABSTRACT FROM AUTHOR]

C18H21N3O2, triclinic, P1̅ (no. 2), a = 8.5155(4) Å, b = 10.6415(4) Å, c = 19.0732(10) Å, α = 80.918(4)°, β = 89.689(4)°, γ = 80.666(4)°, V = 1683.74(14) Å3, Z = 4, Rgt(F) = 0.055, wRref(F2) = 0.133, T = 100 K. [ABSTRACT FROM AUTHOR]

S-4-methylbenzyl-β-N-(2-furylmethylene)dithiocarbazate (S4MFuH, 1 ) derived from the condensation reaction of furaldehyde (Fu) with S-4-methylbenzyldithiocarbazate (S4MBDTC) has been complexed with transition metal acetates to give Zn(S4MFu) 2 ( 2 ), Cd(S4MFu) 2 ( 3 ), Cu(S4MFu) 2 ( 4 ) and Ni(S4MFu) 2 ( 5 ). It is evident from the shift in ν (C N) and ν (N N) in the IR spectra of the complexes that deprotonated 1 acts as a bidentate ligand coordinating through the azomethine nitrogen and thiolato sulfur atoms. This was confirmed by single crystal X-ray diffractometry. The U-shaped dithiocarbazate 1 exists in the E configuration with the thione bond anti to the azo bond. A change in conformation is noted in the transition metal complexes resulting from deprotonation and N S-chelation. 2 and 3 display a distorted tetrahedral geometry with the major cause of the distortion being two close intramolecular M…O interactions. Binding interaction studies with calf thymus DNA demonstrated that 4 also had the strongest DNA binding affinity ( K b = 2.85 × 10 4 M −1 ) among all compounds prepared in this work. The Cu(II) complex, 4 , was also moderately active against estrogen receptor-positive breast cancer cells, MCF-7 (IC 50 = 3.02 μM) while the remainder were inactive against MCF-7 and all showed no activity towards receptor negative breast cancer cells, MDA-MB-231. [ABSTRACT FROM AUTHOR]

Abstract: Mixed-ligand complexes of general formula, [Cu(NNS)(sac)] (NNS′= S-benzyl-β-N-(2-acetylpyrid-2-yl)methylenedithiocarbazate, NNS″= S-benzyl-β-N-(2-benzoylpyrid-2-yl)methylenedithiocarbazate and NNS‴= S-benzyl-β-N-(6-methylpyrid-2-yl)methylenedithio-carbazate, sac=the saccharinate anion) have been synthesized by reacting [Cu(sac)2(H2O)4]·2H2O with the appropriate ligands in ethanol and characterized by various physico-chemical techniques. Magnetic and spectral evidence indicate that the complexes are four-coordinate in which the Schiff bases coordinate as NNS ligands and the sac- anion coordinates as a unidentate N-donor ligand. An X-ray crystallographic structural analysis of [Cu(NNS′)(sac)] shows that the complex has a distorted square-planar geometry with the Schiff base coordinated to the copper (II) ion as a uninegatively charged tridentate chelating agent via the pyridine nitrogen atom, the azomethine nitrogen atom and the thiolate sulphur atom while the fourth coordination position is occupied by the N-bonded saccharinate anion. The complexes have been evaluated for their biological activities against selected pathogens and cancer cell lines. They display weak activity against the pathogenic bacteria and fungi. The complexes were highly active against the leukemic cell line (HL-60) but only [Cu(NNS′)(sac)] was found to exhibit strong cytotoxicity against the ovarian cancer cell line (Caov-3). All complexes were inactive against the breast cancer cell line (MCF-7). [Copyright &y& Elsevier]

Three tridentate Schiff bases containing N and S donor atoms were synthesized via the condensation reaction between S-2-methylbenzyldithiocarbazate with 2-acetyl-4-methylpyridine ( S2APH ); 4-methyl-3-thiosemicarbazide with 2-acetylpyridine ( MT2APH ) and 4-ethyl-3-thiosemicarbazide with 2-acetylpyridine ( ET2APH ). Three new, binuclear and mixed-ligand copper(II) complexes with the general formula, [ Cu(sac)(L) ] 2 (sac = saccharinate anion; L = anion of the Schiff base) were then synthesized, and subsequently characterized by IR and UV/Vis spectroscopy as well as by molar conductivity and magnetic susceptibility measurements. The Schiff bases were also spectroscopically characterized using NMR and MS to further confirm their structures. The spectroscopic data indicated that the Schiff bases behaved as a tridentate NNS donor ligands coordinating via the pyridyl-nitrogen, azomethine-nitrogen and thiolate-sulphur atoms. Magnetic data indicated a square pyramidal environment for the complexes and the conductivity values showed that the complexes were essentially non-electrolytes in DMSO. The X-ray crystallographic analysis of one complex, [Cu(sac)(S2AP)] 2 showed that the Cu(II) atom was coordinated to the thiolate-S, azomethine-N and pyridyl-N donors of the S2AP Schiff base and to the saccharinate-N from one anion, as well as to the carbonyl-O atom from a symmetry related saccharinate anion yielding a centrosymmetric binuclear complex with a penta-coordinate, square pyramidal geometry. All the copper(II) saccharinate complexes were found to display strong cytotoxic activity against the MCF-7 and MDA-MB-231 human breast cancer cell lines. [ABSTRACT FROM AUTHOR]

Metal complexes of dithiocarbazate Schiff bases (abbreviated as NiSMdiAP, CoSMdiAP, FeSMdiAP, MnSMdiAP and ZnSMdiAP, where SMdiAP represents the Schiff base) were synthesized and characterized using techniques including Fourier transform infrared spectroscopy, nuclear magnetic resonance, 1 H NMR, 13 C NMR, magnetic susceptibility measurements, molar conductivity, ultraviolet–visible spectroscopy, and inductively coupled plasma-optical emission spectrometry. The study focused on the oxidation of cyclohexane by using the metal complexes as catalysts with hydrogen peroxide as the oxidative source under special conditions. These catalysts showed good conversion and high selectivity compared to other Schiff base complexes. The conditions of the oxidation reaction catalysed by these complexes were investigated. Gas chromatography was used to analyse the products of the oxidation reaction of cyclohexane and it showed that cyclohexanol and cyclohexanone are the main products. A copper complex of Schiff base formed from 2,6-diacetyl pyridine and S-methyldithiocarbazate, [Cu II SMdiAP] showed the highest level of activity during the screening studies towards cyclohexane oxidation. The time of reaction, temperature, and the concentration of H 2 O 2 as an environmentally friendly oxidant and the catalyst type played an important role in the selectivity and conversion of cyclohexane oxidation. The selectivity of the reaction was 98%. [ABSTRACT FROM AUTHOR]

Thiosemicarbazone Schiff bases 1 and 4 are useful lead candidates for future organic drug design development to treat cancers. Diphenyltin(IV) compounds 5, 8, 11 and 14 exhibited excellent cytotoxic activity against all the cancer cell lines tested. • Thiosemicarbazone Schiff bases 1 & 4 are useful lead candidates for anticancer drug development. • Diphenyltin(IV) compounds with trigonal bipyramidal geometry had excellent cytotoxicity. • Compounds 5, 8, 11 & 14 had the highest cytotoxicity against ten cancer cell lines tested. • Compounds 5, 8, 11 & 14 had low cytotoxicity against normal breast cancer cells MCF-10A. Twelve tin(IV) compounds (5 – 16) derived from four tridentate thiosemicarbazone Schiff bases of 4-methyl-3-thiosemicarbazide with 2-hydroxy-3-methoxybenzaldehyde (1, 2) and 4-phenyl-3-thiosemicarbazide with 2,3-dihydroxybenzaldehyde (3, 4) of the general formulae [R 2 Sn(L n)] and [Sn(L n) 2 ] (where R = Ph or Me; L n = 1 , 2 , 3 and 4) were synthesized and characterized by elemental analysis, IR, UV–vis, mass spectrometry and multinuclear NMR (1H, 13C and 119Sn) spectroscopy. X-ray crystallographic data was obtained for 11′ , a 2:1 co-crystal between Ph 2 Sn(L2) (11) and 3-methoxysalicylaldehyde azine, and Me 2 Sn(L2) (12) where L2H 2 is 2-(2-hydroxy-3-methoxybenzylidene)- N -phenylhydrazinecarbothioamide. The analysis revealed distinct coordination geometries for 11 and 12 approaching trigonal–bipyramidal. In the crystal of 11′ , supramolecular dimers arising from amine N H...S(thiolate) hydrogen bonding and {...HNCS} 2 synthons are evident; π(chelate ring)...π(oxidobenzylidene) stacking is also apparent. In the crystal of 12 , supramolecular, helical chains are generated by a combination of amine N H...O(phenoxide) hydrogen bonding and Sn...S secondary bonding. The cytotoxic activity of the compounds against a panel of ten cancer cell lines, [HT29 (colon), U87 and SJ-G2 (glioblastoma), MCF-7 (breast), A2780 (ovarian), H460 (lung), A431 (skin), DU145 (prostate), BE2-C (neuroblastoma) and MIA (pancreas), and one normal cell line, MCF-10A (normal breast)] were investigated. The thiosemicarbazone Schiff bases 1 and 4 as well as the diphenyltin(IV) compounds showed a strong ability to inhibit the growth of cancer cells, with particular selectivity against HT29, MCF-7, A2780, A431, BE2-C, SJ-G2 and MIA cell lines. The structure–activity relationship of all these compounds were studied by evaluating the effect of alkyl and aryl groups attached on the thiosemicarbazone backbone, the methoxy/hydroxyl groups present at the meta -position of the phenyl ring and alkyl or aryl groups bound to the tin center. [ABSTRACT FROM AUTHOR]

Four new mixed-ligand Ni(II) complexes (1 – 4) containing imidazole (im) or benzimidazole (bz) and tridentate Schiff bases derived from 2,4-dihydroxybenzaldehyde (24D) and 4-methyl-3-thiosemicarbazide (MT24D) or 4-phenyl-3-thiosemicarbazide (PT24D) were synthesised and characterised using elemental and spectral analysis including FTIR, UV–Vis, 1H NMR, 13C NMR and mass spectrometry for Schiff bases, while the complexes were additionally analysed using ICP-OES, molar conductivity, magnetic susceptibility measurements and single crystal X-Ray diffraction (SXRD) analysis. Magnetic susceptibility indicated a square planar geometry for all the metal complexes while molar conductance values showed that the complexes were non-electrolytes in DMSO. The molecular geometries of the neutral complex molecule in [Ni(MT24D)(bz)](bz). CH 3 OH (2′), that is 2 co-crystallised with a 1,3-benzimidazole molecule as a methanol solvate, and in the cation of [Ni(MT24D)(im)]O 2 CMe.2H 2 O (5), a reaction intermediate for 1 , were established by X-ray crystallography. Each featured a trans-N 2 OS coordination geometry defined by phenoxide-O, imine-N and thiolate-S (2′) or thione-S (5) donors as well as the imine-N donors derived from 1,3-benzimidazole (2′) or imidazole (5) molecules. Systematic variations in geometric parameters were correlated with the form of the tridentate ligand, i.e. di-anionic (2′) or mono-anionic (5). In the crystal of 2′ , supramolecular chains were sustained by hydrogen bonding and these were connected into a supramolecular layer by π ... π stacking interactions occurring between coordinated benzimidazole rings. In the crystal of 5 , hydrogen bonding led to a three-dimensional architecture. The Schiff bases and mixed-ligand Ni(II) complexes were tested for their cytotoxic activitY, but all compounds were inactive against the MDA-MB-231 and MCF-7 breast cancer cell lines. Interestingly, the antibacterial analysis of the compounds showed that the PT24D Schiff base, Ni(MT24D)im, Ni(MT24D)bz, and Ni(PT24D)bz complexes had specific and selective activity against Staphylococcus aureus (S. aureus), Bacillus subtilis (B. subtilis), Propionibacterium acne (P. acne) and Enterobacteraerogenes (E. aerogenes). The DNA binding studies of mixed-ligand Ni(II) complexes against calf thymus DNA revealed that slight hypochromism was observed in the absorption spectra suggesting π-π interactions between the aromatic chromophores and the DNA base pairs where 2 had higher K b values than 1 thus indicating stronger interactions. Image 1 • New mixed-ligand Ni(II) complexes containing imidazole derivatives are reported. • The single crystal structures of the complexes were unexpected. • The neutral complex 2′ co-crystallised with 1,3-benzimidazole as a methanol solvate. • The cationic complex (5) was a reaction intermediate from 1. • The complexes were active against some of the bacterial strains tested. [ABSTRACT FROM AUTHOR]