Impact and correlation of pKaand dnelectrons of some selected thiosemicarbazone Schiff base metal Co, Ni, Cu complexes: a study of electrochemical behavior, excitation and optical energies

The electron-transfer and coordination mechanism of thiosemicarbazone Schiff bases with metal ions (Co, Ni, Cu), correlation of the electrochemical and optical properties for their potential applications in various fields of chemistry and biochemistry are underexplored.

Chelation, spectroscopic characterization, biological activity and crystal structure of 2,3-butanedione isonicotinylhydrazone: Determination of Zr(4+) after flotation separation

New metal complexes of Co(II), Ni(II) Cu(II), Zn(II), Cd(II), Pd(II) and Hg(II) with 2,3-butanedione isonicotinylhydrazone [BINH] have been prepared and investigated. Single crystal for BINH is grown and solved as orthorhombic with P 21 21 2 space group. The formula of the ligand was assigned based on the elemental analysis, mass spectra and conductivity measurements. The complexes assigned the formulae [M(BINH-H)Cl]⋅nH2O (MCo(II), Ni(II), Cu(II), Zn(II); n=0 or 1); [Hg(BINH-H)(H2O)2Cl]; [Cd(BINH)Cl2]⋅2H2O and [Pd(BINH)Cl2]⋅H2O. All complexes are nonelectrolytes. BINH acts as a tridentate ligand in [M(BINH-H)Cl]⋅nH2O and [Hg(BINH-H)(H2O)2Cl] coordinating through COketonic, COamedic and CNhy and as a neutral bidentate through COketonic and CNhy in [Cd(BINH)Cl2]⋅2H2O and [Pd(BINH)Cl2]⋅H2O; the pyridine nitrogen has no rule in coordination. The data are supported by NMR ((1)H and (13)C) spectra. The magnetic moments and electronic spectra provide a tetrahedral structure for the Co(II), Ni(II), Cu(II), Zn(II) and Cd(II) complexes; square-planar for the Pd(II) complex and octahedral for the Hg(II) complex. The TGA of the complexes depicted the outer and inner water molecules as well as the final residue. The cobalt and cadmium complexes ended with the metal while the Cu(II), Zn(II) and Pd(II) complexes ended with complex species. [Hg(BINH-H)(H2O)2Cl] has no residue. The ligand is inactive against all tested organisms except for Bacillus thuringiensis. The Hg(II) complex is found more active than the other complexes. The flotation technique is found applicable for the separation of micro amount (10ppm) of Zr(4+) using 10ppm of BINH and 1×10(-5)molL(-1) of oleic acid at pH 6 with efficiency of 98% with no interferences.

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.

Spectroscopic characterization and biological activity of dihydrazone transition metal complexes: crystal structure of 2,3-butanedione bis(isonicotinylhydrazone)

Metal complexes of the chloride, nitrate and acetate salts of Co(II), Ni(II) Cu(II), Zn(II), Cd(II) or Hg(II) with 2,3-butanedione bis(isonicotinylhydrazone) [BBINH] have been synthesized and structurally characterized. The crystal of BBINH was solved to crystallize as monoclinic system with space group of P121/c14. The formulae of the complexes were assigned based on the elemental analysis and mass spectra. The formation of BBINH complexes depend on the metal anion used. All complexes are nonelectrolytes except for the complexes 2, 3, 4 are (1:1) and 13 and 14 which are 1:2 electrolytes. BBINH behaves as a neutral tetradentate (N2O2) in the chloride complexes of Ni(II), Cu(II), Zn(II), Cd(II) and Hg(II). In [Co2(BBINH)(H2O)Cl3]Cl⋅H2O, BBINH has the same dentate but with the two Co(II) ions. In the acetate complexes, [Ni2(BBINH-2H)(H2O)2(OAc)2]⋅3H2O and [Cu2(BBINH-2H)(OAc)2]⋅5H2O, BBINH acts as a binegative tetradentate with the two metal ions. The ligand in the nitrate complexes acts as a neutral bidentate via the two hydrazone azomethine C=NHy; the nitrate ions are ionic in the Cd(II) and Zn(II) complexes and covalent in the Ni(II) complex. The data are supported by NMR ((1)H and (13)C) spectra. The magnetic moments and electronic spectra of all complexes provide tetrahedral, square planar and/or octahedral structure. The decomposition of the complexes revealed the outer and inner solvents as well as the remaining residue based on TGA. The complexes have variable activities against some bacteria and fungi. The ligand is inactive against all tested organisms. The activity of Cd(II) and Hg(II) may be related to the geometry of the complexes.

Synthesis, characterization, biological activity of binuclear Co(II), Cu(II) and mononuclear Ni(II) complexes of bulky multi-dentate thiosemicarbazide

The chelation behavior of 9,10-dihydro-9,10-ethanoanthracene-11,12-dicarbonyl) bis (N-ethylhydrazine-1-carbothioamide) (H6ETS)(1) towards Co(2+), Ni(2+)and Cu(2+) have been studied. The spectral data revealed that the ligand acts as a bi- and/or mono-negative multi-dentate. The isolated Ni(II) and Cu(II) complexes are square-planar while the Co(II) is tetrahedral. EPR spectrum of Cu(II) complex confirmed simulated an axial spin-Hamiltonian exhibiting a four-line pattern with nitrogen super-hyperfine couplings originating from imine hydrazinic nitrogen atoms and possess a significant amount of tetrahedral distortion leading to a pseudo-square-planar geometry with unpaired electron has d(x(2)-y(2)) ground state. Also, the thermal behavior and kinetic parameters were determined. Furthermore, the title compounds were investigated for their antibacterial activity using inhibition zone diameter and for DNA degradation, superoxide-scavenging activity as well as hydroxyl radicals that generated by the oxidation of cytochrome c in L-ascorbic acid/CuSO4-cytochrome c system.

Synthesis, characterization and biological study on Cr(3+), ZrO(2+), HfO(2+) and UO(2)(2+) complexes of oxalohydrazide and bis(3-hydroxyimino)butan-2-ylidene)-oxalohydrazide

Cr(3+), ZrO(2+), HfO(2+) and UO(2)(2+) complexes of oxalohydrazide (H(2)L(1)) and oxalyl bis(diacetylmonoxime hydrazone) [its IUPAC name is oxalyl bis(3-hydroxyimino)butan-2-ylidene)oxalohydrazide] (H(4)L(2)) have been synthesized and characterized by partial elemental analysis, spectral (IR; electronic), thermal and magnetic measurements. [Cr(L(1))(H(2)O)(3)(Cl)].H(2)O, [ZrO(HL(1))(2)].C(2)H(5)OH, [UO(2)(L(1))(H(2)O)(2)] [ZrO(H(3)L(2))(Cl)](2).2H(2)O, [HfO(H(3)L(2))(Cl)](2).2H(2)O and [UO(2)(H(2)L(2))].2H(2)O have been suggested. H(2)L(1) behaves as a monobasic or dibasic bidentate ligand while H(4)L(2) acts as a tetrabasic octadentate with the two metal centers. The molecular modeling of the two ligands have been drawn and their molecular parameters were calculated. Examination of the DNA degradation of H(2)L(1) and H(4)L(2) as well as their complexes revealed that direct contact of [ZrO(H(3)L(2))(Cl)](2).2H(2)O or [HfO(H(3)L(2))(Cl)](2).2H(2)O degrading the DNA of Eukaryotic subject. The ligands and their metal complexes were tested against Gram's positive Bacillus thuringiensis (BT) and Gram's negative (Escherichia coli) bacteria. All compounds have small inhibitory effects.

Modification of chloromethylated polystyrene with 2-mercabtobenzothiazole for application as a new sorbent for preconcentration and determination of Ag+ from different matrices

Chloromethylated polystyrene polymer (CMSP) modified with 2-mercabtobenzothiazole (MBT) has been developed for the selective separation and/or preconcentration of silver. The modified polymer (CMS-MBT) was characterized by elemental analysis and IR spectra. Batch and column modes were applied. The newly designed polymer quantitatively sorbed Ag(+) at pH 2 when the flow rate is 5 ml min(-1). The maximum sorption capacity was 0.493 mmol g(-1) while the preconcentration factor was 250 for Ag(+). The detection limit was 8 ng ml(-1). The desorption was effective with 5 ml of 2 mol l(-1) HNO(3) prior to detection using AAS. The modified polymer was highly ion-selective in nature even in the presence of large concentrations of electrolytes or organic media, with a preconcentrating ability for Ag(+). The utility of the modified polymer to synthetic and drugs samples showed RSD values of <3% reflecting its accuracy and reproducibility.

Synthesis and spectral feature of benzophenone-substituted thiosemicarbazones and their Ni(II) and Cu(II) complexes

The ligational behavior of 2-hydroxybenzophenone and 2-hydroxy-4-methoxybenzophenone N-substituted thiosemicarbazones towards Ni(II) and Cu(II) ions has been investigated. The isolated complexes were identified by elemental analyses, molar conductance, magnetic moment, IR, UV-vis and ESR spectral studies. The IR spectra indicated that the investigated thiosemicarbazones lost the N(2) proton or the N(2) and OH protons and act as mononegative or binegative tridentate ligands. The ligands containing methoxy group facilitate the deprotonation of OH by resonance more than the SH. Most of the Ni(II) complexes measured subnormal magnetic moments due to square-planar+tetrahedral configuration and supported by the electronic spectra. The percentage of square-planar to tetrahedral was calculated and found in agreement with the ligand splitting energy (10Dq). Also, Cu(II) complexes measured subnormal values due to the interaction between copper centers; the lower the value the higher the interaction. It was found that the substitutent has a noticeable effect on the distortion of the complex. The ESR spectra of some solid Cu(II) complexes at room temperature exhibit g(parallel)>g( perpendicular)>2.0023 confirming a square-planar structure.

Synthesis and structural investigation of mono- and polynuclear copper complexes of 4-ethyl-1-(pyridin-2-yl) thiosemicarbazide

The reaction between 2-hydrazinopyridine and ethylisothiocyanate produced 4-ethyl-1-(pyridin-2-yl) thiosemicarbazide (HEPTS). Its reaction with copper fluoride, chloride, bromide, acetate, nitrate, perchlorate, sulfate, carbonate, hydroxide and copper metal produced 15 Cu(II) complexes. The copper metal is easily oxidized in aqueous-ethanol solution of HEPTS giving [Cu2(EPTS)(H2O)3(OH)3]EtOH. Different complexes for the same anion were synthesized by controlling the heating time. Characterization by elemental, thermal, magnetic and spectral (electronic, IR, mass and ESR) studies showed the formation of mono-, di-, tri- and tetra nuclear complexes. The room temperature solid state ESR spectra of the complexes show an axial spectrum with dx2-y2 ground state, suggesting distorted tetragonal geometry around Cu(II) center. The kinetic and thermodynamic parameters for the different decomposition steps in the complexes were calculated. HEPTS and its Cu(II) complexes showed high activity against gram negative bacteria; [Cu3(EPTS)2(EtOH)2Br4] has more activity.

Spectral, thermal, electrochemical and analytical studies on Cd(II) and Hg(II) thiosemicarbazone complexes

The coordination characteristic of the investigated thiosemicarbazones towards hazard pollutants, Cd(II) and Hg(II), becomes the first goal. Their complexes have been studied by microanalysis, thermal, electrochemical and spectral (electronic, IR and MS) studies. The substitutent (salicylaldehyde, acetophenone, benzophenone, o-hydroxy-p-methoxybenzophenone or diacetylmonoxime) plays an important role in the complex formation. The coordination sites were the S for thiosemicarbazide (HTS); NN for benzophenone thiosemicarbazone (HBTS); NS for acetophenone thiosemicarbazone (HATS) and salicylaldehyde thiosemicarbazone (H2STS); NNS or NSO for diacetylmonoxime thiosemicarbazone (H2DMTS). The stability constants of Hg(II) complexes were higher than Cd(II). The kinetic and thermodynamic parameters for the different thermal decomposition steps in the complexes have been evaluated. The activation energy values of the first step ordered the complexes as: [Cd(H2STS)Cl2]H2O > [Cd(H2DAMTS)Cl2] > [Cd(HBTS)2Cl2]2H2O > [Cd(HATS)2Cl2]. The CV of [Cd(H2STS)Cl2]H2O and [Hg(HBTS)Cl2] were recorded. The use of H2DMTS as a new reagent for the separation and determination of Cd(II) ions from water and some synthetic samples using flotation technique is aimed to be discussed.

A novel method for speciation of Cr(III) and Cr(VI) and individual determination using Duolite C20 modified with active hydrazone

Trivalent and hexavalent chromium have been successfully separated and estimated from different solutions using 1-(3,4-dihydroxybenzaldehyde)-2-acetylpyridiniumchloride hydrazone (DAPCH) loaded on Duolite C20 in batch and column modes. The obtained modified resin [DAPCH-Duolite C20] was identified by C, H and N analyses and infrared spectra. The presence of multi-active chelating sites gives the ability for DAPCH to bind more chromium, Cr(III) by forming stable complex and chromate by forming ion pair molecule [H(2)DAPCH-Duolite C20](2+)[Cr(2)O(7)](2-) (H(2)DAPCH-Duolite C20 is the protonated form in acidic medium). The extraction isotherms were measured at different pH. The pH was found to be the backbone for the separation procedure in which the Cr(VI) and Cr(III) ions are sorbed selectively from aqueous solution at pH 2 and 6, respectively. The sorbed ions can be eluted using different concentrations of HCl. The saturation sorption capacity (41.6 and 20.05 mg g(-1)), the preconcentration factor (150 and 200) and the detection limit (13.3 and 10.0 ppb) were calculated for Cr(III) and (VI). The loaded resin can be regenerated for at least 50 cycles. The utility of the modified resin was tested in aqueous samples and shows R.S.D. value of <4% reflecting its accuracy and reproducibility.

Synthesis, spectral characterization and eukaryotic DNA degradation of thiosemicarbazones and their platinum(IV) complexes

The condensation products of acetophenone (or its derivatives), salicylaldehyde and o-hydroxy-p-methoxybenzophenone with thiosemicarbazide and ethyl- or phenyl-thiosemicarbazide are the investigated thiosemicarbazones. Their reactions with H(2)PtCl(6) produced Pt(IV) complexes characterized by elemental, thermal, mass, IR and electronic spectral studies. The coordination modes were found mononegative bidentate in the acetophenone derivatives and binegative tridentate in the salicylaldehyde derivatives. The complexes were analyzed thermogravimetrically and found highly stable. Some ligands and their complexes were screened against Sarcina sp. and E. coli using the cup-diffusion technique. [Pt(oHAT)(OH)Cl] shows higher activity against E. coli than the other compounds. The degradation power of the tested compounds on the calf thymus DNA supports their selectivity against bacteria and not against the human or related eukaryotic organisms.

Physical and spectroscopic studies on novel vanadyl complexes of some substituted thiosemicarbazides

Complexes of V(IV)O with N(4) ethyl and/or phenyl thiosemicarbazides have been prepared to study the role of substituents, on the two sides of thiosemicarbazide moiety, on the behavior of the complex formation. The study of ligands in solution reflected the dependence of their ionization values on the nature of the function groups neighboring the active sites. Two main (octahedral and square-pyramid) structures have been characterized for the solid complexes by the well known methods. There is some similarity between the structure and the color of the obtained complexes. Three modes of chelation were suggested for the investigated complexes. Complete disappearance of the nitrile group during the complex formation with cyano ligands is attributed to the promotion of water molecules to the cyano group. The intensity and position of the VO band in the IR spectra reflect not only the nature of the ligand but also the geometry of the complex formed. Some complexes were isolated as binuclear and confirmed by ESR spectra. The end product on thermal degradation of most complexes was VO(2).

Spectroscopic, thermal and electrochemical studies on some nickel(II) thiosemicarbazone complexes

Several complexes of thiosemicarbazone derivatives with Ni(II) have been prepared. Structural investigation of the ligands and their complexes has been made based on elemental analysis, magnetic moment, spectral (UV-Vis, i.r., (1)H NMR, ms), and thermal studies. The i.r. spectra suggest the bidentate mononegative and tridentate (neutral, mono-, and binegative) behavior of the ligands. Different stereochemistries were suggested for the isolated complexes. The thermogravimetry (TG) and derivative thermogravimetry (DTG) have been used to study the thermal decomposition and kinetic parameters of some ligands and complexes using the Coats-Redfern and Horowitz-Metzger equations. The redox properties and stability of the complexes toward oxidation waves explored by cyclic voltammetry are related to the electron withdrawing or releasing ability of the substituent of thiosemicarbazone moiety. The samples displayed Ni(II)/Ni(I) couples irreversible waves associated with Ni(III)/Ni(II) process.