Manganese(II) complexes of hydrazone based NNO-donor ligands and their catalytic activity in the oxidation of olefins

The reaction between tridentate NNO donor hydrazone ligands, (E)-2-cyano-N′-(phenyl(pyridin-2-yl)methylene)acetohydrazide (HL¹) and (E)-2-cyano-N′-(1-(pyridin-2-yl)ethylidene)acetohydrazide (HL²), with MnCl₂·4H₂O in methanol resulted in [Mn(HL¹)Cl₂(CH₃OH)] (1) and [Mn(HL²)Cl₂(CH₃OH)] (2). Molecular structures of the complexes were determined by single-crystal X-ray diffraction. All of the investigated compounds were further characterized by elemental analysis, FT-IR, TGA, and UV–Vis spectroscopy. These complexes were used as catalysts for olefin oxidation in the presence of tert-butylhydroperoxide (TBHP) as an oxidant. Under similar experimental conditions with equal manganese loading, the presence of [Mn(HL²)Cl₂(CH₃OH)] (2) resulted in higher conversion than [Mn(HL¹)Cl₂(CH₃OH)] (1).     

Copper complexes with a flexible piperazinyl arm: nuclearity driven catecholase activity and interactions with biomolecules

Three new Cu(II) complexes, [Cu(HL¹)(pyridine)(H₂O)](ClO₄)₂·2MeOH (1), [Cu₂(HL¹)₂(NO₃)₂](NO₃)₂·3H₂O (2) and [Cu(HL₂)(NO₃)₂]·MeCN (3), have been synthesized from two Schiff base ligands [HL¹ = 1-phenyl-3-((2-(piperazin-4-yl)ethyl)imino)but-1-en-1-ol and HL² = 4-((2-(piperazin-1-yl)ethyl)imino)pent-2-en-2-ol] using the chair conformer of a flexible piperazinyl moiety. Structural analysis reveals that 1 and 3 are monomeric Cu(II) complexes consisting of five- and six-coordinate Cu(II), respectively, whereas 2 is a dinuclear Cu(II) complex consisting of two different Cu(II) centers, one square planar with the other distorted octahedral. Screening tests were conducted to quantify the binding of 1–3 towards DNA and BSA as well as the DNA cleavage activity of these complexes using gel electrophoresis. Enzyme kinetic studies were also performed for the complexes mimicking catecholase-like activities. Antibacterial activities of these complexes were also examined towards Methicillin-Resistant Staphylococcus aureus bacteria. The results reflect that 2 is more active than the monomeric complexes, which is further corroborated by density functional theory study.     

Tin(IV), titanium(IV) and hafnium(IV) complexes of some aromatic Schiff bases derived from 4-aminoantipyrine

Summary Tin(IV), titanium(IV) and hafnium(IV) chloride complexes of ligands such as salicylidene-4-aminoantipyrine (HL¹), 5-chlorosalicylidene-4-aminoantipyrine (HL²), 2,4-dihydroxybenzylidene-4-aminoantipyrine (HL³), 2-hydroxy-1-naphthylidene-4-aminoantipyrine (HL⁴) and 2-hydroxyacetophenonylidene-4-aminoantipyrine (HL⁵) have been prepared and characterized. The analytical data show that tin(IV) forms only 1:1 metal complexes when reacted with HL¹, HL³ and HL⁴, whereas it forms 1:1 and 1:2 metal complexes when reacted with HL², depending on the molar ratio. HL⁵ produces only the binuclear complex SnHL⁵Cl₄(H₂O)SnCl₄. Titanium(IV) gives only one type of complex of the general formula [Ti(HL)₂Cl₂]Cl₂-2H₂O, whilst hafnium(IV) gives HfHL³Cl₄-4H₂O and Hf(L⁵)₂Cl₂.     

Chemical and Electrochemical Preparation for Co(II) Complexes of Some Novel Pyridine-2-(1H)-Thione Ring Fused Cycloalkane Derivatives

Anodic oxidation of cobalt and copper metals in an anhydrous acetone solution of pyridine-2-(1H)-thione-3-cyano-4-(2-bromophenyl)-5,6-ring fused cycloheptane (HL¹) and its derivatives, (HL²), (HL³), (HL⁴), (HL⁵), (HL⁶), (HL⁷), (HL⁸), and (HL⁹) yields complexes of composition [M(L)₂·(H₂O)₂]·n H₂O and [M(L)₂·(acetone)₂], where M = Co(II) or Cu(II) and L is the ligand. Also, reaction of an aqueous ethanolic solution of Co(Ac)₂·2H₂O with the previous ligands was prepared. Elemental analysis, and infrared and electronic spectral data are presented to confirm the formulation of the amorphous complexes. The spectral data indicate that the ligands are coordinated to the metal via the thioenol sulfur atom and the nitrogen atom of cyano groups. The ligands reacts in the enol form through the anodic dissolution of the ligands or during the reaction with metal salts. The ligand field parameters and crystal field splitting energies, Δ_o, for different cobalt metal complexes were calculated.     

Syntheses,characterization and X-ray crystal structures of Ni(II) complexes of tridentate monocondensed and tetradentate dicondensed Schiff bases

Two octahedral complexes [Ni(HL¹)₂](ClO₄)₂ (1) and [Ni(HL²)₂](ClO₄)₂ (2) and a square planar complex [Ni(HL³)]ClO₄ (3) have been prepared, where [HL¹ = 3-(2-amino-ethylimino)-butan-2-one oxime, HL² = 3-(2-amino-propylimino)butan-2-one oxime] and H₂L³ = 3-[2-(3-hydroxy-1-methyl-but-2-enylideneamino)-1-methyl-ethylimino]-butan-2-one oxime. All the complexes have been characterized by elemental analyses, spectral studies and room temperature magnetic moment measurements. The molecular structures of all three compounds were elucidated on the basis of X-ray crystallography; complexes 1 and 2 are seen to be the mer isomers.     

Synthesis,characterization, and antitumour studies of some curcuminoid analogues and their aluminum complexes

Aluminum(III) complexes of three curcuminoid analogues [1,7-diphenyl-1,6-heptadiene-3,5-dione, HL¹; 1,7-bis(2-hydroxyphenyl)-1,6-heptadiene-3,5-dione, HL²; and 1,7-bis(4-ethoxyphenyl)-1,6-heptadiene-3,5-dione, HL³] of [AlL₃] stoichiometry were synthesized and characterized by UV, IR, ¹H NMR, and mass spectral data. The compounds were investigated for cytotoxic and antitumor activities. The aluminum chelates are remarkably active compared to free curcuminoid analogues. The aluminum complex of HL² with hydroxyl in the phenyl ring was most active towards Ehrlich ascites carcinoma cells (concentration needed for 50% inhibition of 5?μg/mL) and cultured L929 cells (1?μg/mL produced 60?+?3% cell death). Increase in lifespan and reduction of solid tumor volume in mice were also largest for the aluminum complex of HL². The study reveals that the antitumor activities of curcuminoids are more enhanced by complexation with aluminum than with transition metal ions.     

Synthesis and study of the structure of new 3d-metal coordination compounds with substituted 2-amino-4(5H)-ketothiophens

A series of new 3d-metal complexes based on 2-amino-3-(1-methylbenzimidazol-2-yl)-4(5H)-ketothiophen (HL¹) and 2-amino-3-(2-benzothiazolyl)-4(5H)-ketothiophen (HL²) were synthesized. Compounds of the general formulas [ML₂] and [M(HL¹)₂Cl₂] (where M = Co²⁺, Ni²⁺, Zn²⁺, Cu²⁺) were prepared by the reaction of the above mentioned ligands with the corresponding acetate (for [ML₂]) or chloride (for [M(HL¹)₂Cl₂]) salts in a methanol or a methanol–chloroform medium. The choice of the anion in the initial metal salt, as well as the selection of the ligand, is crucial for obtaining coordination compounds with a neutral or deprotonated form of the 2-amino-4(5H)-ketothiophens. Thus, in contrast to HL¹, complexes with the neutral form of HL² cannot be obtained under the same conditions. All the complexes were studied by spectroscopic methods and X-ray crystallography (for [CuL¹₂] · H₂O). The coordination polyhedron of the copper atom is formed by four nitrogen atoms from two ligand anions and the geometry of the coordination sphere is intermediate between tetrahedral and square-planar.     

Synthesis,structure, and properties of coordination compounds of copper(II) acetate with substituted 2-{[2-(2-hydroxyethylamino)ethylimino]methyl}phenol

Salicylic, 5-chloro-5-bromo-5-nitro-, 3-methoxysalicylic, 2-hydroxy-1-naphthoic aldehydes and 2,3-, 2,4-, and 2,5-dihydroxybenzaldehyde were shown to react in ethanol with 2-(2-aminoethylamino)ethanol in the presence of copper acetate hydrate forming coordination compounds Cu(L^1-9)CH₃COO {HL^1-8, 2-([2-(2-hydroxyethylamino)ethylimino]methyl}phenol (HL¹) and respective chloro(HL²), bromo- (HL³), nitro- (HL⁴), methoxy- (HL⁸), or hydroxy-substituted (HL^5-7); HL⁹, 2-{[2-(2-hydroxyethylamine)ethylimino] methylnaphthol)}. Structure of the complex Cu(L³)CH₃COO was determined by X-ray diffraction analysis. Coordination polyhedron of its central atom is a distorted tetragonal bipyramid with (4+1+1) modes of coordinating the copper atom. The bipyramid base is formed by the atoms of phenol oxygen and of azomethine and imine nitrogen atoms of the ligand (HL³) and the oxygen atom of the acetate ion. Axial apices of the bipyramid are occupied by the alcohol oxygen atoms of the azomethine (HL³) and the second oxygen atom of the acetate ion. Other complexes are also of monomer structure. Azomethines (HL^1-9) behave as monodeprotonated tetradentate O,N,N,O ligands. The thermolysis of substances includes a stage of complete thermal decomposition (360–530°C). Synthesized complexes show selective antimicrobial activity against a series of standard strains of Staphylococcus aureus and E. coli at the concentration in the range of 75–300 μg ml⁻¹.     

Carbonylative Suzuki coupling reactions catalyzed by ONO pincer–type Pd(II) complexes using chloroform as a carbon monoxide surrogate

Benzoylhydrazone Schiff base–ligated three new ONO pincer–type palladium(II) complexes, [(PdL¹(PPh₃)] ( 1 ), [(PdL²(PPh₃)] ( 2 ), and [(PdL³(PPh₃)] ( 3 ), were synthesized by the reaction of the respective ligand, N-(2-hydroxybenzylidene)benzohydrazide (HL¹), N-(2-hydroxy-3-methoxybenzylidene)benzohydrazide (HL²), or N-(5-bromo-2-hydroxybenzylidene) benzohydrazide (HL³), with Pd(OAc)₂ and PPh₃ in methanol and isolated as air-stable reddish-orange crystalline solids in high yields (78%–83%). All three complexes were fully characterized by elemental analysis, Fourier-transform infrared spectroscopy, UV–Visible, ¹H nuclear magnetic resonance (NMR), ¹³C{¹H} NMR, and ³¹P{¹H} NMR spectroscopic studies. The molecular structure of all three complexes was established unambiguously by single-crystal X-ray diffraction studies which revealed a distorted square planar geometry of all three complexes. The ONO pincer–type ligands occupied three coordination sites at the palladium, while the fourth site is occupied by the monodentate triphenylphosphine ligand. The catalytic potential of all three complexes was explored in the carbonylative Suzuki coupling of aryl bromides and iodides with arylboronic acids to yield biaryl ketones, using CHCl₃ as the source of carbonyl. The reported protocol is convenient and safe as it obviates the use of carbon monoxide (CO) balloons or pressured CO reactors which are otherwise needed for the carbonylation reactions. The methodology has been successfully applied to the synthesis of two antineoplastic drugs, namely, phenstatin and naphthylphenstatin, in good yields (81% and 85%, respectively). Under the optimized reaction conditions, complex 2 exhibited the best catalytic activity in the carbonylative Suzuki couplings. The reported catalysts have wide reaction scope with good functional group tolerance. All catalysts could be retrieved from the reaction after completion and recycled up to three times with insignificant loss in the catalytic activity.     

Ni(II) complexes with pyrazole-derived ligands. Crystal structures of [Ni(HL0)2ClH2O][Ni(HL0)2(H2O)2]Cl3·CH3OH·H2O and [Ni(HL1)2(H2O)2]Br2·2.5DMF (HL0=3-phenyl-5-(2-pyridyl)pyrazole and HL1=3-phenyl-5-(6-methyl-(2-pyridyl))pyrazole

The reaction of 3-phenyl-5-(2-pyridyl)pyrazole (HL⁰) and 3-phenyl-5-(6-methyl-(2-pyridyl))pyrazole (HL¹) with nickel(II) salts produces mononuclear coordination compounds. The new complexes have been characterised by elemental analyses, conductivity measurements and infrared and electronic spectroscopies.Two different forms of mononuclear nickel(II) complexes have been prepared and structurally characterised by X-ray crystallography: [Ni(HL⁰)₂Cl(H₂O)][Ni(HL⁰)₂(H₂O)₂]Cl₃·CH₃OH·H₂O and [Ni(HL¹)₂(H₂O)₂]Br₂·2.5DMF. In the cationic complexes, the coordination of the Ni(II) is octahedral with two bidentate HL⁰ or HL¹ neutral ligands in a cis disposition. The degree of distortion from regular octahedral geometry is compared to closely related structures. In the solid state, cations and anions are bonded by hydrogen bonding.     

Synthesis,spectral, thermal and crystallographic investigations on oxovanadium(IV) and manganese(III) complexes derived from heterocyclic β-diketone and 2-amino ethanol

Novel mononuclear oxovanadium(IV) and manganese(III) complexes [VO(L¹)₂·H₂O] (1); [VO(L²)₂·H₂O] (2); [VO(L³)₂·H₂O] (3); [Mn(L¹)₂]ClO₄·H₂O (4); [Mn(L²)₂] ClO₄·H₂O (5); [Mn(L³)₂]ClO₄·H₂O (6) were prepared by condensation of 1 mol of VOSO₄·5H₂O or Mn(OAc)₃· 2H₂O with 2 mol of ligand HL¹, HL² or HL³ (where HL¹ = 4-[(2-hydroxy-ethylamino)-methylene]-5-methyl-2- phenyl-2,4-dihydro-pyrazol-3-one; HL²=4-[(2-hydroxy-ethylamino)-methylene]-5-methyl-2-p-tolyl-2,4-dihydro-pyrazol-3-one; HL³=4-{4-[(2-hydroxy-ethyl-amino)-methyl]-3-methyl-5-oxo-4,5-dihydropyrazol-1-yl} benzene sulfonic acid). The resulting complexes were characterized by elemental analyses, molar conductance, magnetic and decomposition temperature measurements, electron spin resonance, FAB mass, IR and electronic spectral studies. From TGA, DTA and DSC, the thermal behaviour and degradation kinetic were studied. Electronic spectra and magnetic susceptibility measurements indicate distorted octahedral stereochemistry of oxovanadium(IV) complexes and regular octahedral stereochemistry of manganese(III) complexes. Hamiltonian and bonding parameters found from ESR spectra indicate the metal ligand bonding is partial covalent. The X-ray single crystal determination of one of the representative ligand was carried out which suggests existence of amine-one tautomeric form in the solid state. The ¹H-NMR spectra support the existence of imine-ol form in solution state. The LC-MS studies sustain the¹H-NMR result. The electronic structure of the same representative ligand was optimized using 6-311G basis set at HF level ab initio studies to predict the coordinating atoms of the ligand.     

Effect of Structure and Composition of Copper and Cobalt Complexes with Schiff Base Ligands on their DNA/Protein Interaction and Cytotoxicity

Four transition metal complexes, namely Cu₂Cl₂(HL¹)₂ ( 1 ), Co(HL¹)₂ ( 2 ), Cu(HL²)₂ ( 3 ), Co(HL²)₃ ( 4 ) {H₂L¹ = 2‐{[2‐(2‐hydroxy‐ethoxy)‐ethylimino]‐methyl}‐phenol, H₂L² = 3‐{[2‐(2‐hydroxy‐ethoxy)‐ethylimino]‐methyl}‐naphthalen‐2‐ol} were synthesized and characterized by single‐crystal X‐ray diffraction, IR spectroscopy, and elemental analysis. The interactions of these copper and cobalt complexes with calf thymus DNA (CT‐DNA) were studied by absorption and emission titration spectroscopic methods. The interactions of these copper and cobalt complexes with bovine serum albumin (BSA) were also investigated using fluorescence, UV/Vis, and synchronous fluorescence spectroscopy. Further, the in vitro cytotoxic effect of the complexes are examined on human colon carcinoma cell lines (HCT‐116) and human lung carcinoma cell line (A549).     

Synthesis,structures, and urease inhibition of nickel(II), zinc(II), and cobalt(II) complexes with similar hydroxy-rich Schiff bases

Four new nickel(II), zinc(II), and cobalt(II) complexes, [Zn(L¹)₂]?·?H₂O (1), [Ni(L¹)₂]?·?H₂O (2), [Ni(L²)₂] (3), and [Co(L³)₂]?·?H₂O (4), derived from hydroxy-rich Schiff bases 2-{[1-(5-chloro-2-hydroxyphenyl)methylidene]amino}-2-methylpropane-1,3-diol (HL¹), 2-{[1-(2-hydroxy-3-methoxyphenyl)methylidene]amino}-2-ethylpropane-1,3-diol (HL²), and 2-{[1-(5-bromo-2-hydroxyphenyl)methylidene]amino}-2-methylpropane-1,3-diol (HL³) have been synthesized and characterized by elemental analyses, infrared spectroscopy, and single-crystal X-ray determination. Each metal in the complexes is six-coordinate in a distorted octahedral coordination. The Schiff bases coordinate to the metal atoms through the imino N, phenolate O, and one hydroxyl O. In the crystal structures of HL¹ and the complexes, molecules are linked through intermolecular O–H···O hydrogen bonds, forming 1-D chains. The urease inhibitory activities of the compounds were evaluated and molecular docking study of the compounds with the Helicobacter pylori urease was performed.     

Specifics of luminescence of (benzoxazolyl)phenolate and (benzothiazolyl)naphtholate heterometallic Zn,Sc, Nd,Sm, Er,and Yb complexes

Heterometallic complexes Ln(L¹)₅Zn (Ln = Sc, Sm, Gd) were obtained by the reactions of silylamides Ln[N(SiMe)₂]₃ with 2-(benzoxazol-2-yl)phenol (HL¹) in the presence of diethylzinc. Similar reactions with 3-(benzothiazol-2-yl)-2-naphthol (HL²) led to the formation of complexes Ln(L²)₅Zn (Ln = Nd, Er, Gd, Yb). The introduction of the zinc-containing fragments provided a considerable increase of photo- and electroluminescence intensity of the scandium complex.     

Copper(II), nickel(II) and cobalt(II) complexes of 5,5-dimethylcyclohexane-1,2,3-trione-2-arylhydrazones

Summary Copper(II), nickel(II) and cobalt(II) perchlorate complexes of 5,5-dimethylcyclohexane-1,2,3-trione-2-(p-nitrophenyl-hydrazone) (HL¹), 5,5-dimethyl-cyclohexane-1,2,3-trione-2-(p-chlorophenylhydrazone) (HL²), 5,5-dimethylcyclohexane-1,2,3-trione-2-(o-chlorophenylhydrazone) (HL⁴), 5,5-dimethylcyclohexane-1,2,3-trione-2-(o-methylphenyl-hydrazone) (HL⁵) and 5,5-dimethylcyclohexane-1,2,3-trione-2-(m-methylphenylhydrazone) (HL⁶) have been prepared, and characterized using analytical, spectral and magnetic measurements. The data reveal that the reaction of Cu(ClO₄)₂ (1 mol) in EtOH, with all ligands, produces complexes of the type CuL(ClO₄)(H₂O).nH₂O. Nickel(II) and cobalt(II) perchlorates react only with HL¹ and HL² to produce the complexes ML(ClO₄)(H₂O)₃ (where M = Ni^II, L = L^– and L², M = Co^II, L = L¹) and Co(HL₂)₂-(ClO₄)₂.2H₂O. The spectral data show that the ligands behave as monobasic bidentate in their azo forms, except HL² which reacts with cobalt(II) as a neutral bidentate ligand in its hydrazone form.     

Preparation,spectral characterization,in vitro antitumor and thermal studies of new platinum(IV) and palladium(II) thiohydrazone complexes

Pt^IV and Pd^II complexes [Pt(L)₂Cl₂] and [Pd(HL)Cl₂] [HL = salicyclaldehyde morpholine N-thiohydrazone (HL¹), benzaldehyde morpholine N-thiohydrazone (HL²), acetophenone morpholine N-thiohydrazone (HL³), p-methylacetophenone morpholine N-thiohydrazone (HL⁴), cinnamaldehyde morpholine N-thiohydrazone (HL⁵), cyclohexanone morpholine N-thiohydrazone (HL⁶), benzaldehyde aniline N-thiohydrazone (HL⁷), benzaldehyde N-(methyl, cyclohexyl)-thiohydrazone (HL⁸) and benzaldehyde N-(ethyl, cyclohexyl)-thiohydrazone (HL⁹)] were prepared in MeOH and characterized by elemental analysis, i.r., electronic, ¹H-n.m.r. and ¹³C-n.m.r. spectral data. For some of the complexes cyclic voltammetric and thermal studies were carried out. The in vitro antitumor activity of some complexes was measured.     

Unveiling the binding interaction of zinc (II) complexes of homologous Schiff-base ligands on the surface of BSA protein: A combined experimental and theoretical approach

Four new zinc (II) complexes [Zn (HL¹H)Br₂] (1), [Zn (HL¹H)Cl₂] (2), [Zn₂(HL²)Br₃] (3), and [Zn (HL²)Cl] (4) have been synthesized by adopting template synthetic strategy and utilizing two homologous Schiff base ligands (H₂L¹ = 4-bromo-2-{[2-(2-hydroxyethylamino)-ethylimino]-methyl}-6-methoxyphenol, H₂L² = 4-bromo-2-{[3-(2-hydroxyethylamino)propylimino]methyl}-6-methoxyphenol), differing in one -CH₂- unit in the ligating backbone, by adopting template synthetic strategy. All the complexes have been characterized by single crystal X-ray diffraction analysis as well as by other routine physicochemical techniques. Ligand mediated structural variations have been observed and rationalized by density functional theoretical (DFT) calculations. Interaction of the complexes 1–4 with Bovine Serum Albumin protein (BSA) has been studied by different spectroscopic techniques. A complete thermodynamic profile (ΔH^o, ΔS^o and ΔG^o) was evaluated initially from the change in absorption and fluorescence spectra upon addition of BSA to the complexes. Appreciable binding constant values in the range ~ 0.94–4.51 × 10⁴ M⁻¹ indicate efficient binding tendency of the complexes to BSA with the sequence 1 ≅ 2 > 3 ≅ 4. Circular dichroism (CD), isothermal calorimetric titration experiments, molecular docking and molecular dynamics have been performed to gain deep insight into the binding regions of complex 1 to BSA. Experimental evidences suggest an interaction of zinc complexes at the surface of BSA protein and this particular binding has been exploited to determine unknown concentration of BSA protein. For this purpose complex 1 was explored as a BSA protein quantification tool.     

Synthesis,crystal structure and spectral characterization of Co(II) complexes with acylpyrazolone ligands

The three new Cobalt(II) complexes [Co(L¹)₂(H₂O)₂] (1), [Co(L²)₂(H₂O)₂] (2), and [Co(L³)₂(H₂O)₂] (3) have been synthesized by interaction of acyl pyrazolone ligands, 4-(4-chlorobenzoyl)3-methyl1-phenyl1H-pyrazole5(4H)-one (HL¹), 4-(4-chlorobenzoyl)1-(3-chlorophenyl)3-methyl1H-pyrazole5(4H)-one (HL²) and 5-methyl4-(4-methylbenzoyl)2-phenyl2,4-dihydro3H-pyrazole3-one (HL³) with CoCl₂.6H₂O. The complexes were screened using FTIR, UV–Vis, TGA, and Single Crystal X-ray diffraction spectroscopic techniques. A relative study of the ligands’ FTIR spectra and their metal complexes reveal the formation, sifting, and disappearance of several bands during complexation. Other interpretations stipulated that these three complexes are mononuclear and exhibited octahedral geometry around Co²⁺.Triclinic crystal system, Distortion in Octahedral geometry, and Intermolecular hydrogen bonding confirmed by Single-crystal XRD analysis of [Co(L³)₂(EtOH)₂] complex.     

Synthesis,DNA-binding properties and cytotoxicity evaluation of two copper(II) complexes based on curcumin

Two Cu(II) complexes based on curcumin, namely CuL ₂ ¹ [HL¹ = 1,7-bis[4-(2-oxymethylenepyridine)-3-methoxyl]phenyl-1,6-heptadiene-3,5-diketone] and CuL ₂ ² [HL² = 1,7-bis[4-(3-oxymethylene-2-chlorothiophene)-3-methoxyl] phenyl-1,6-heptadiene-3,5-diketone], have been synthesized and characterized by physico-chemical and spectroscopic methods. The interactions of calf thymus DNA (CT-DNA) with both complexes have been investigated by UV–Vis absorption, fluorescence and viscosity titration methods. Both complexes are found to interact with CT-DNA by intercalative binding modes. Evaluation of the cytotoxicities of the complexes against three human tumor cells showed that they have potent cytotoxicities against all three cell lines.     

Transition Metal Complexes with the Thiosemicarbazide-based ligands. XII. Complexes of nickel(II) with benzoylacetone S-methylisothiosemicarbazone and N(1)-2-butylidene-4-oxo-4-phenyl-N(4)-salicylidene-S-methylisothiosemicarbazide

A template synthesis procedure yielded [Ni(HL¹)NH₃]I, where HL¹ is the monoanion of the terdentate ONN benzoylacetone S-methylisothiosemicarbazone ligand. The reaction of this complex with an excess of NH₄NCS, pyridine, or hydrazine resulted in the complexes [Ni(HL¹)(NH₃)NCS] and [Ni(L¹)A] (A = Py, N₂H₄). The monoanionic form of the ligand is obtained by deprotonation of the enolic form of the benzoylacetone moiety, whereas the dianion is formed by additional deprotonation of the terminal NH₂ group. Finally, the reaction of [Ni(HL¹)NH₃]I with salicyladehyde produced the NiL² complex in which L² stands for the dianion of the ONNO ligand N(1)-2-butylidene-4-oxo-4-phenyl-N(4)-salicylidene-S-methylisothiosemicarbazide. All complexes are diamagnetic and have a square-planar configuration, except for [Ni(HL¹)(NH₃)NCS], for which te data of i.r. spectra suggest a square-pyramidal structure. The electronic absorption spectra of the ethanolic solutions of all complexes are characteristic of typical square-planar coordination of nickel(II).