Tawfik H. Rakha

Synthesis, characterization, DFT and biological studies of isatinpicolinohydrazone and its Zn(II), Cd(II) and Hg(II) complexes.

Isatinpicolinohydrazone (H2IPH) and its Zn(II), Cd(II) and Hg(II) complexes have been synthesized and investigated using physicochemical techniques viz. IR, (1)H NMR, (13)C NMR, UV-Vis spectrometric methods and magnetic moment measurements. The investigation revealed that H2IPH acts as binegative tetradentate in Zn(II), neutral tridentate in Cd(II) and as neutral bidentate towards Hg(II) complex. Octahedral geometry is proposed for all complexes. The bond length, bond angle, chemical reactivity, energy components (kcal/mol), binding energy (kcal/mol) and dipole moment (Debyes) for all the title compounds were evaluated by DFT and also MEP for the ligand is shown. Theoretical infrared intensities of H2IPH and also the theoretical electronic spectra of the ligand and its complexes were calculated. The thermal behavior and the kinetic parameters of degradation were determined using Coats-Redfern and Horowitz-Metzger methods. The in vitro antibacterial studies of the complexes proved them as growth inhibiting agents. The DDPH antioxidant of the compounds have been screened. Antitumor activity, carried out in vitro on human mammary gland (breast) MCF7, have shown that Hg(II) complex exhibited potent activity followed by Zn(II), Cd(II) complexes and the ligand.

First row transition metal complexes of (E)-2-(2-(2-hydroxybenzylidene) hydrazinyl)-2-oxo-N-phenylacetamide complexes

Manganese(II), iron(II), cobalt(II), nickel(II), copper(II), and chromium(III) complexes of (E)-2-(2-(2-hydroxybenzylidene)hydrazinyl)-2-oxo-N-phenylacetamide were synthesized and characterized by elemental and thermal (TG and DTA) analyses, IR, UV-vis and (1)H NMR spectra as well as magnetic moment. Mononuclear complexes are obtained with 1:1 molar ratio except [Mn(HOS)(2)(H(2)O)(2)] and [Co(OS)(2)](H(2)O)(2) complexes which are obtained with 1:2 molar ratios. The IR spectra of ligand and metal complexes reveal various modes of chelation. The ligand behaves as a monobasic bidentate one and coordination occurs via the enolic oxygen atom and azomethine nitrogen atom. The ligand behaves also as a monobasic tridentate one and coordination occurs through the carbonyl oxygen atom, azomethine nitrogen atom and the hydroxyl oxygen. Moreover, the ligand behaves as a dibasic tridentate and coordination occurs via the enolic oxygen, azomethine nitrogen and the hydroxyl oxygen atoms. The electronic spectra and magnetic moment measurements reveal that all complexes possess octahedral geometry except the copper complexes possesses a square planar geometry. From the modeling studies, the bond length, bond angle, HOMO, LUMO and dipole moment had been calculated to confirm the geometry of the ligands and their investigated complexes. The thermal studies showed the type of water molecules involved in metal complexes as well as the thermal decomposition of some metal complexes. The protonation constant of the ligand and the stability constant of metal complexes were determined pH-metrically in 50% (v/v) dioxane-water mixture at 298 K and found to be consistent with Irving-Williams order. Moreover, the minimal inhibitory concentration (MIC) of these compounds against Staphylococcus aureus, Escherechia coli and Candida albicans were determined.

Transition Metal Chelates Derived from Potassium Nicotinoyldithiocarbazate (KHNDC)

Abstract Mononuclear and polynuclear chelates of nicotinoyldithiocarbazate (HNDC−) with Fe(III), Mn(II), Fe(II), Co(II), Ni(II), Zn(II), Cd(II), Hg(II), Pd(II), Cu(I) and Ag(I) have been prepared. The chelates have been characterized by chemical and thermal (TG, DTG, DTA) analyses, molar conductivity, spectral (UV-Visible, IR, NMR) and magnetic susceptibility measurements. The molar conductivities of the complexes lie in the non-electrolyte range whilst KHNDC is a 1:1 electrolyte. The IR spectral data show that KHNDC behaves in a monoanionic bidentate or tetradentate and dianionic tetradentate manner. The Iigand field parameters (B, Dq, β) for the Fe(III), Co(II) and Ni(II) complexes were calculated and related to the electronic environments. The solid metal acetate complexes have a unique decomposition exotherm profile which can be used as a rapid and sensitive tool for the detection of acetate-containing complexes.

Transition Metal Complexes from N-Anthranilamido-N′-benzoylthiocarbamide (H2ABTC)

Abstract Complexes of N-anthranilamido-N′-benzoylthiocarbamide (H2ABTC) with Cr(III), Mn(II), Co(II), Ni(II), Cu(II), Zn(II), Cd(II) and UO2(VI) have been synthesized and characterized on the basis of elemental analyses, molar conductivities, spectral (IR and visible) and magnetic studies. IR spectral data show that the ligand behaves in a neutral bidentate, mononegative bidentate or tridentate and binegative tridentate or tetradentate manner. All the complexes are non-electrolytes. Different stereochemistries are proposed for the Cr(III), Mn(II), Co(II), Ni(II) and Cu(II) complexes according to the data of magnetic and electronic spectral measurements. IR data indicate that the carbonyl oxygen of the benzoyl moiety is the backbone of the chelating agent in all the complexes.

Synthesis and structural studies on bivalent metal complexes of benzenesulphonylhydrazine

SummaryBenzenesulphonylhydrazine (HB) reacts with bivalent metal ions either in the keto-or enol forms. The complexes have been characterized by spectral (u.v., i.r., n.m.r.,), magnetic and thermal (d.t.a., d.t.g, t.g., d.s.c.) measurements. I.r. spectra suggest that HB is monodentate coordinatingvia NH or NH2, depending on the medium of the reaction. The participation of the O=S=O group in bondingvia bridge-formation in a polymeric chain is also considered. The substitution of ethanol in the CoII complex, [(CoB2EtOH)n], by H2O, pyridine or acetonitrile was also investigated.

Ligational Behaviour of 1-Picolinoyl–4-phenyl–3-thiosemicarbazide (H2PTS) Towards Some Transition Metal Ions

Abstract Complexes of 1-picolinoly-4-phenyl-3-thiosemicarbazide (H2PTS) with Cr(III), Mn(II), Fe(III), Co(II), Ni(II), Cu(II), Zn(II), Cd(II), Hg(II) and UO2(VI) have been synthesized and characterized on the basis of elemental analyses, molar conductivities, magnetic moment and spectral (IR and visible) studies. IR spectral data show that H2PTS behaves in a monoanionic bidentate or tetradentate and bianionic tetradentate manner. All complexes are non-electrolytes. An octahedral structure is proposed for the Cr(III), Mn(II), Fe(III), Co(II) and Ni(II) complexes, while a square-planar one is suggested for Cu(HPTS)Cl.H2O and Cu(PTS) according to the data of magnetic and electronic spectral measurements.

Ligational, thermal, corrosion inhibition and antimicrobial properties of salicylidinebenzenesulphonylhydrazone

SummaryComplexes of CuII, CoII, NiII, CdII, ZnII and HgII with salicylidinebenzenesulphonylhydrazone (HSBS) have been prepared and characterized by elemental analyses, molar conductivities, magnetic moments, spectral (visible, i.r., n.m.r.) and thermal (d.t.a., t.g., d.t.g.) measurements. The magnetic and spectral studies confirm that the NiII complex is square, whereas the CoII complex is tetrahedral. The molar conductivities for the complexes lie in the non-electrolyte range. The corrosion inhibition of aluminium using HSBS was studied by chemical and electrochemical methods. Also, the antimicrobial activities of HSBS and its complexes have been investigated.

MONONUCLEAR AND BINUCLEAR CHELATES OF BIACETYLMONOXIME PICOLINOYLHYDRAZONE

Mononuclear and binuclear chelates of biacetylmonoxime picolinoylhydrazone (H2BMPcH) with CrIII, FeIII, CoII, NiII, CuII, ZnII, CdII, PdII and UO22+ have been prepared. Elemental analyses, molar conductivities, spectral (u.v., visible, i.r., n.m.r., e.s.r.), thermal (t.g., d.t.g., d.t.a.) and magnetic susceptibility measurements have been used to characterize the chelates. The i.r. spectral data indicate that H2BMPcH behaves in a bidentate, tridentate and/or tetradentate manner and the hydrazonic azomethine nitrogen constituents the chelating backbone in all chelates. Based on magnetic and spectroscopic data, the structures for the chelates are proposed as follows: tetrahedral for [Co(HBMPcH)(H2O)]Cl, octahedral for [Co(HBMPcH)2], [Cr(HBMPcH)Cl(H2O)]2Cl2, [Fe(HBMPcH)Cl-(H2O)]2Cl2, [Ni(BMPcH)(H2O)2], square-planar for (Ni(HBMPcH)Cl], [Pd(HBMPcH)Cl], [Cu(HBMPcH)(H2O)]Cl and tetragonally distorted octahedral for [Cu(BMPcH)(H2O)2]2 chelates. Generally, the solid metal acetate complexes have a unique decomposition exotherm profile which can be used as a rapid and sensitive tool for the detection of acetate-containing complexes.

Synthesis, spectral, thermal and biological studies on N(-)(2,4-dinitro-phenyl)-2-mercaptoacetohydrazide and its metal complexes.

Complexes of VO(2+), Cr(3+), Co(2+), Ni(2+), Cu(2+), Zn(2+), Cd(2+) and Hg(2+) ions with N(-)(2,4-dinitrophenyl)-2-mercaptoacetohydrazide (H2L) have been prepared and characterized on the basis of elemental analysis, molar conductance, thermal (TGA, DTGA), spectral (IR, NMR, UV-Visible, MS) and magnetic measurements. The IR spectra show that H2L behaves in a mononegative and/or binegative bidentate manner. The sulfate bridged the two complex molecules in [Cu(HL)(H2O)2(½SO4)]⋅3H2O. The acetate functions as a monodentate in [Ni(HL)(OAc)(H2O)3] and [Cr(HL)(OAc)2(H2O)(EtOH)]. Different stereochemistries are proposed: octahedral for Cr(III), Ni(II), Hg(II) and [Cu(HL)(H2O)2(SO4)0.5]⋅3H2O, square-based pyramid for [VO(HL)2]⋅EtOH, square-planar for [Co(L)(EtOH)(H2O)]⋅H2O, [Cu(L)(H2O)2] and tetrahedral for [Zn(L)(EtOH)(H2O)], [Cd(L)(EtOH)(H2O)] and [Cu2(HL)(H2O)6]Cl3⋅H2O according to the data of electronic spectra and magnetic measurements. The TGA data support the formula and indicate the outer and inner solvents as well as the final residue. The thermodynamic parameters are calculated using the Coats-Redfern and Horowitz-Metzger methods. H2L and [Zn(L)(EtOH)(H2O)] showed the highest cytotoxic activity while H2L has a higher antioxidant activity than ascorbic acid. The ionization constant of the ligand and the stability constant of the Cu(II)H2L in absence and presence of hexamine buffer were calculated.

The dangers of using KBr, KI and CaI2 as mulling agents during the preparation of infrared discs of complexes

Tribochemical reactions of KBr, KI and CaI2 with [Cu(L)Cl2(EtOH)3/2(H2O)]1/2H2O (L = formylhydrazine) give novel CuI and CuII complexes, which have been characterized by elemental analyses, spectral (i.r., u.v.–vis., 1H-n.m.r.) and magnetic measurements. The i.r. spectra indicate that (L) behaves in a monodentate manner, coordinating via the azomethine nitrogen (C-N) group in the CuII complexes, but behaving as a bidentate ligand, via the carbonyl oxygen and NH2 groups in the CuI complexes. KI and CaI2 react with [Cu(L)Cl2(EtOH)3/2(H2O)]-1/2H2O in the solid state, accompanied by a colour change, substitution of the chloride by iodide ions, and reduction of CuII to CuI to give complexes with formulae [Cu(L)I(EtOH)1/2] and [Cu1.7(L)I1.7(EtOH)1/2]. On the other hand, the tribochemical reaction of KBr with [Cu(L)Cl2(EtOH)3/2(H2O)]1/2H2O is accompanied by a colour change; substitution of the chloride by bromide ions, but without reduction of CuII and yields a complex of formula [Cu(L)2Br2(EtOH)(H2O)]1/2EtOH. The spectral and magnetic results suggest a distorted octahedral geometry for the CuII complexes while a tetrahedral geometry around the CuI ion. The non-stoichiometric structure of [Cu1.7(L)I1.7(EtOH)1/2] is discussed.