Mixed ligand complexes of bis(phenylimine) Schiff base ligands incorporating pyridinium moiety Synthesis, characterization and antibacterial activity

The synthesis and structural characterization of mixed ligand complexes derived from 2,6-pyridinedicarboxaldehydebis(o-hydroxyphenylimine), 2,6-pyridinedicarboxaldehydebis(p-hydroxyphenylimine) (1(ry) ligands) and 2-aminopyridne (2(ry) ligand) are reported. The ligands and their transition metal complexes were characterized on the bases of their elemental analyses, IR, solid reflectance, magnetic moment, molar conductance and thermal analysis (TGA). The mixed ligand complexes are formed in the 1:1:1 (M:L(1) or L(2):L') ratio as found from the elemental analyses and found to have the formulae [MX(2)(L(1) or L(2))(L')].nH(2)O where M = Co(II), Ni(II), Cu(II) and Zn(II), L(1) = 2,6-pyridinedicarboxaldehydebis(p-hydroxyphenylimine), L(2) = 2,6-pyridine dicarboxaldehydebis(o-hydroxyphenylimine), L' = 2-aminopyridine, X = Cl(-) in case of Cu(II) complex and Br(-) in case of Co(II), Ni(II) and Zn(II) complexes and y = 0-3. The molar conductance data reveal that the chelates are non-electrolytes. IR spectra show that the Schiff bases are coordinated to the metal ions in a terdentate manner with NNN donor sites of the pyridine-N and two azomethine-N. While 2-aminopyridine coordinated to the metal ions via its pyridine-N. Magnetic and solid reflectance spectra are used to infer the coordinating capacity of the ligand and the geometrical structure of these complexes are found to be octahedral. The thermal behaviour of these chelates shows that the hydrated water molecules and the anions are removed in a successive two steps followed immediately by decomposition of the ligands (L(1), L(2) and L') in the subsequent steps. The activation thermodynamic parameters, such as, E*, DeltaH*, DeltaS* and DeltaG* are calculated from the TG curves and discussed. The ligands and their metal chelates have been screened for their antimicrobial activities and the findings have been reported, explained and compared with some known antibiotics.     

Synthesis, structural, thermal studies and biological activity of a tridentate Schiff base ligand and their transition metal complexes

Schiff base (L) ligand is prepared via condensation of pyridine-2,6-dicarboxaldehyde with -2-aminopyridine. The ligand and its metal complexes are characterized based on elemental analysis, mass, IR, solid reflectance, magnetic moment, molar conductance, and thermal analyses (TG, DTG and DTA). The molar conductance reveals that all the metal chelates are non-electrolytes. IR spectra shows that L ligand behaves as neutral tridentate ligand and bind to the metal ions via the two azomethine N and pyridine N. From the magnetic and solid reflectance spectra, it is found that the geometrical structures of these complexes are octahedral (Cr(III), Fe(III), Co(II), Ni(II), Cu(II), and Th(IV)) and tetrahedral (Mn(II), Cd(II), Zn(II), and UO2(II)). The thermal behaviour of these chelates shows that the hydrated complexes losses water molecules of hydration in the first step followed immediately by decomposition of the anions and ligand molecules in the subsequent steps. The activation thermodynamic parameters, such as, E*, ΔH*, ΔS* and ΔG* are calculated from the DTG curves using Coats-Redfern method. The synthesized ligand, in comparison to their metal complexes also was screened for its antibacterial activity against bacterial species, Escherichia coli, Pseudomonas aeruginosa, Staphylococcus pyogones and Fungi (Candida). The activity data shows that the metal complexes to be more potent/antibacterial than the parent Schiff base ligand against one or more bacterial species.     

Potentiometric, spectroscopic and thermal studies on the metal chelates of 1-(2-thiazolylazo)-2-naphthalenol

The synthesis and characterization of Mn(II), Fe(III), Co(II), Ni(II), Cu(II), Zn(II), Cd(II), Pd(II) and UO2(II) chelates of 1-(2-thiazolylazo)-2-naphthalenol (TAN) were reported. The dissociation constants of the ligand and the stability constants of the metal complexes were calculated pH-metrically at 25 degrees C and 0.1 M ionic strength. The solid complexes were characterized by elemental and thermal analyses, molar conductance, IR, magnetic and diffuse reflectance spectra. The complexes were found to have the formulae [M(L)2] for M = Mn(II), Co(II), Ni(II), Zn(II) and Cd(II); [M(L)X].nH2O for M = Cu(II) (X = AcO, n = 3), Pd(II) (X = Cl, n = 0) and UO2(II) (X = NO3, n = 0), and [Fe(L)Cl2(H2O)].2H2O. The molar conductance data reveal that the chelates are non-electrolytes. IR spectra show that the ligand is coordinated to the metal ions in a terdentate manner with ONN donor sites of the naphthyl OH, azo N and thiazole N. An octahedral structure is proposed for Mn(II), Fe(III), Co(II), Ni(II), Zn(II), Cd(II) and UO2(II) complexes and a square planar structure for Cu(II) and Pd(II) complexes. The thermal behaviour of these chelates shows that water molecules (coordinated and hydrated) and anions are removed in two successive steps followed immediately by decomposition of the ligand molecule in the subsequent steps. The relative thermal stability of the chelates is evaluated. The final decomposition products are found to be the corresponding metal oxides. The thermodynamic activation parameters, such as E*, delta H*, delta S* and delta G* are calculated from the TG curves.     

Synthesis, characterization and biological activity of some transition metals with Schiff base derived from 2-thiophene carboxaldehyde and aminobenzoic acid

Metal complexes of Schiff base derived from 2-thiophene carboxaldehyde and 2-aminobenzoic acid (HL) are reported and characterized based on elemental analyses, IR, 1H NMR, solid reflectance, magnetic moment, molar conductance and thermal analysis (TGA). The ligand dissociation as well as the metal-ligand stability constants were calculated pH metrically at 25 degrees C and ionic strength mu=0.1 (1M NaCl). The complexes are found to have the formulae [M(HL)2](X)n.yH2O (where M=Fe(III) (X=Cl, n=3, y=3), Co(II) (X=Cl, n=2, y=1.5), Ni(II) (X=Cl, n=2, y=1) and UO2(II) (X=NO3, n=2, y=0)) and [M(L)2] (where M=Cu(II) (X=Cl) and Zn(II) (X=AcO)). The molar conductance data reveal that Fe(III) and Co(II), Ni(II) and UO2(II) chelates are ionic in nature and are of the type 3:1 and 2:1 electrolytes, respectively, while Cu(II) and Zn(II) complexes are non-electrolytes. IR spectra show that HL is coordinated to the metal ions in a terdentate manner with ONS donor sites of the carboxylate O, azomethine N and thiophene S. From the magnetic and solid reflectance spectra, it is found that the geometrical structure of these complexes are octahedral. The thermal behaviour of these chelates shows that the hydrated complexes losses water molecules of hydration in the first step followed immediately by decomposition of the anions and ligand molecules in the subsequent steps. The activation thermodynamic parameters, such as, E*, DeltaH*, DeltaS* and DeltaG* are calculated from the DrTG curves using Coats-Redfern method. The synthesized ligands, in comparison to their metal complexes also were screened for their antibacterial activity against bacterial species, Escherichia coli, Pseudomonas aeruginosa, Staphylococcus pyogones and Fungi (Candida). The activity data show that the metal complexes to be more potent/antibacterial than the parent Schiff base ligand against one or more bacterial species.     

Structure investigation, spectral, thermal, X-ray and mass characterization of piroxicam and its metal complexes

[M(H2L)2](A)2.yH2O (where H2L: neutral piroxicam (Pir), A: Cl- in case of Ni(II) or acetate anion in case of Cu(II) and Zn(II) ions and y=0-2.5) and [M(H2L)3](A)z.yH2O (A: SO4(2-) in case of Fe(II) ion (z=1) or Cl(-) in case of Fe(III) (z=3) and Co(II) ions (z=2) and y=1-4) chelates are prepared and characterized using elemental analyses, IR, magnetic and electronic reflectance measurements, mass spectra and thermal analyses. IR spectra reveal that Pir behaves a neutral bidentate ligand coordinated to the metal ions through the pyridyl-N and carbonyl-O of the amide moiety. The reflectance and magnetic moment measurements reveal that these chelates have tetrahedral, square planar and octahedral geometrical structures. Mass spectra and thermal analyses are also used to confirm the proposed formulae and the possible fragments resulted from fragmentation of Pir and its chelates. The thermal behaviour of the chelates (TGA and DTA) are discussed in detail and the thermal stability of the anhydrous chelates follow the order Ni(II) congruent with Cu(II) Fe(II)相似文献   

Synthesis, characterization and thermal studies on metal complexes of new azo compounds derived from sulfa drugs

Four new azo ligands, L1 and HL2-4, of sulfa drugs have been prepared and characterized. [MX(2)(L1)(H(2)O)(m)].nH(2)O; [(MX(2))(2)(HL2 or HL3)(H(2)O)(m)].nH(2)O and [M(2)X(3)(L4)(H(2)O)].nH(2)O; M=Co(II), Ni(II) and Cu(II) (X=Cl) and Zn(II) (X=AcO); m=0-4 and n=0-3, complexes were prepared. Elemental and thermal analyses (TGA and DTA), IR, solid reflectance spectra, magnetic moment and molar conductance measurements have accomplished characterization of the complexes. The IR data reveal that HL1 and HL2-3 ligands behave as a bidentate neutral ligands while HL4 ligand behaves as a bidentate monoionic ligand. They coordinated to the metal ions via the carbonyl O, enolic sulfonamide S(O)OH, pyrazole or thiazole N and azo N groups. The molar conductance data reveal that the chelates are non-electrolytes. From the solid reflectance spectra and magnetic moment data, the complexes were found to have octahedral, tetrahedral and square planar geometrical structures. The thermal behaviour of these chelates shows that the water molecules (hydrated and coordinated) and the anions are removed in a successive two steps followed immediately by decomposition of the ligand in the subsequent steps. The activation thermodynamic parameters, such as, E*, DeltaH*, DeltaS* and DeltaG* are calculated from the TG curves applying Coats-Redfern method.     

Metal complexes of Schiff base derived from sulphametrole and o-vanilin. Synthesis, spectral, thermal characterization and biological activity

Metal complexes of Schiff base derived from condensation of o-vanilin (3-methoxysalicylaldehyde) and sulfametrole [N(1)-(4-methoxy-1,2,5-thiadiazole-3-yl)sulfanilamide] (H2L) are reported and characterized based on elemental analyses, IR, 1H NMR, solid reflectance, magnetic moment, molar conductance, mass spectra, UV-vis and thermal analysis (TGA). From the elemental analyses data, the complexes were proposed to have the general formulae [M2X3(HL)(H2O)5].yH2O (where M=Mn(II), Co(II), Ni(II), Cu(II), Zn(II) and Cd(II), X=Cl, y=0-3); [Fe2Cl5(HL)(H2O)3].2H2O; [(FeSO4)2(H2L)(H2O)4] and [(UO2)2(NO3)3(HL)(H2O)].2H2O. The molar conductance data reveal that all the metal chelates were non-electrolytes. The IR spectra show that, H2L is coordinated to the metal ions in a tetradentate manner with ON and NO donor sites of the azomethine-N, phenolic-OH, enolic sulphonamide-OH and thiadiazole-N. From the magnetic and solid reflectance spectra, it is found that the geometrical structures of these complexes are octahedral. The thermal behaviour of these chelates shows that the hydrated complexes losses water molecules of hydration in the first step followed immediately by decomposition of the anions and ligand molecules in the subsequent steps. The activation thermodynamic parameters, such as, E*, DeltaH*, DeltaS* and DeltaG* are calculated from the DrTG curves using Coats-Redfern method. The synthesized ligand, in comparison to their metal complexes also were screened for their antibacterial activity against bacterial species, Escherichia coli, Salmonella typhi, Bacillus subtillus, Staphylococcus aureus and Fungi (Aspergillus terreus and Aspergillus flavus). The activity data show that the metal complexes to be more potent/antimicrobial than the parent Shciff base ligand against one or more microbial species.     

Spectroscopic characterization,thermogravimetric and antimicrobial studies of some new metal complexes derived from4-(4-Isopropyl phenyl)-2-oxo-6-phenyl 1,2-dihyropyridine-3-carbonitrile (L)

A new series of Fe (III), Co (II), Zn (II), Y (III), Zr (IV) and La (III) complexes derived from the novel ligand 4-(4-Isopropyl phenyl)-2-oxo-6-phenyl 1,2-dihyropyridine-3-carbonitrile (L) were synthesized and characterized. The mode of bonding of L and geometrical structures of their metal complexes were elucidated by different micro analytical and spectral methods (FT-IR,UV–visible,1H NMR and Mass spectra) as well as thermal analysis (TG and DTG), and differential scanning calorimetry (DSC). The results of analytical and spectroscopic equipments revealed that L acts as bidentate through nitrogen of carbonitrile group and oxygen of keto group. The conductivity measurement results deduced that these chelates are electrolyte with 1:2 for Co (II), Zn (II), and Zr (IV) and 1:3 for Fe (III), Y (III), and La (III). The results of magnetic moment measurements supported paramagnetic for some complexes (Fe (III), Co (II) and Cu (II)) and diamagnetic phenomena for the other complexes (Y (III), Zr (IV) and La (III)). Thermodynamic parameters such as energy of activation E*, entropy ΔS*, enthalpy ΔH* and Gibss free energy ΔG* were calculated using Coats-Redfern and Horowitz-Metzeger methods at n = 1 or n#1. Some results of bioactivity tests for ligands and their metal complexes were recorded against Gram-positive, Gram-negative bacteria and antifungal. The complexes showed significant more than free ligand.     

Synthesis, spectroscopic, thermal and antimicrobial studies of some novel metal complexes of Schiff base derived from [N1-(4-methoxy-1,2,5-thiadiazol-3-yl)sulfanilamide] and 2-thiophene carboxaldehyde

Keeping in view the chemotherapeutic of the sulfa-drugs, Schiff base namely 2-thiophene carboxaldehyde-sulfametrole (HL) and its tri-positive and di-positive metal complexes have been synthesized and characterized by elemental analyses, IR, 1H NMR, solid reflectance, magnetic moment, molar conductance, mass spectra, UV-vis and thermal analysis (TGA and DrTG). The low molar conductance values suggest the non-electrolytic nature of these complexes. IR spectra show that HL is coordinated to the metal ions in a tetradentate manner through hetero five-membered ring-S and azomethine-N, enolic sulfonamide-OH and thiadiazole-N, respectively. Zn(II), Cd(II) and UO2(II) complexes are found to be diamagnetic (as expected). The proposed general formulae of the prepared complexes are [M2X4(HL)(H2O)4] (where M=Mn(II), Co(II), Ni(II), Cu(II), Zn(II) and Cd(II), X=Cl, [Fe2Cl6(HL)(H2O)2], [(FeSO4)2(HL)(H2O)4] and [(UO2)2(HL) (NO3)4].H2O. The thermal behaviour of these chelates shows that the hydrated complexes loss water of hydration in first step in case of uranium complexes followed loss coordinated water followed immediately by decomposition of the anions and ligand molecules in the subsequent steps. The activation thermodynamic parameters, such as DeltaE*, DeltaH*, DeltaS*, and DeltaG* are calculated from the DrTG curves using Coats-Redfern method. The antimicrobial activity of the obtained products was performed using Chloramphenicol and Grisofluvine as standards, indicate that in some cases metallation increase activity than the ligand.     

Salisaldehyde-2-aminobenzimidazole schiff base complexes of Fe(III), Co(II), Ni(II), Cu(II), Zn(II) and Cd(II)

New metal complexes of Fe(III), Co(II), Ni(II), Cu(II), Zn(II) and Cd(II) with salicylidine-2-aminobenzimidazole (SABI) are synthesized and their physicochemical properties are investigated using elemental and thermal analyses, IR, conductometric, solid reflectance and magnetic susceptibility measurements. The base reacts with these metal ions to give 1:1 (Metal:SABI) complexes; in cases of Fe(III), Co(II), Cu(II), Zn(II) and Cd(II) ions; and 1:2 (Metal:SABI) complexes; in case of Ni(II) ion. The conductance data reveal that Fe(III) complex is 2:1 electrolyte, Co(II) is 1:2 electrolyte, Cu(II), Zn(II) and Cd(II) complexes are 1:1 electrolytes while Ni(II) is non-electrolyte. IR spectra showed that the ligand is coordinated to the metal ions in a terdentate mannar with O, N, N donor sites of the phenloic -OH, azomethine -N and benzimidazole -N3. Magnetic and solid reflectance spectra are used to infer the coordinating capacity of the ligand and the geometrical structure of these complexes. The thermal decomposition of the complexes is studied and indicates that not only the coordinated and/or crystallization water is lost but also that the decomposition of the ligand from the complexes is necessary to interpret the successive mass loss. Different thermodynamic activation parameters are also reported, using Coats-Redfern method. This revised version was published online in July 2006 with corrections to the Cover Date.     

Synthesis, investigation and spectroscopic characterization of piroxicam ternary complexes of Fe(II), Fe(III), Co(II), Ni(II), Cu(II) and Zn(II) with glycine and DL-phenylalanine

The ternary piroxicam (Pir; 4-hydroxy-2-methyl-N-(2-pyridyl)-2H-1,2-benzothiazine-3-carboxamide 1,1-dioxide) complexes of Fe(II), Fe(III), Co(II), Ni(II), Cu(II) and Zn(II) with various amino acids (AA) such as glycine (Gly) or DL-phenylalanine (PhA) were prepared and characterized by elemental analyses, molar conductance, IR, UV-Vis, magnetic moment, diffuse reflectance and X-ray powder diffraction. The UV-Vis spectra of Pir and the effect of metal chelation on the different interligand transitions are discussed in detailed manner. IR and UV-Vis spectra confirm that Pir behaves as a neutral bidentate ligand coordinated to the metal ions via the pyridine-N and carbonyl group of the amide moiety. Gly molecule acted as a uninegatively monodentate ligand and coordinate to the metal ions through its carboxylic group, in addition PhA acted as a uninegatively bidentate ligand and coordinate to the metal ions through its carboxylic and amino groups. All the chelates have octahedral geometrical structures while Cu(II)- and Zn(II)-ternary chelates with PhA have square planar geometrical structures. The molar conductance data reveal that most of these chelates are non electrolytes, while Fe(III)-Pir-Gly, Co(II)-, Ni(II)-, Cu(II)- and Zn(II)-Pir-PhA chelates were 1:1 electrolytes. X-ray powder diffraction is used as a new tool to estimate the crystallinity of chelates as well as to elucidate their geometrical structures.     

Preparation, characterization and biological activity of Fe(III), Fe(II), Co(II), Ni(II), Cu(II), Zn(II), Cd(II) and UO(2)(II) complexes of new cyclodiphosph(V)azane of sulfaguanidine

Novel hexachlorocyclodiphosph(V)azane of sulfaguanidine, H(4)L, l,3-[N'-amidino-sulfanilamide]-2,2,2,4,4,4-hexachlorocyclodiphosph(V)azane was prepared and its coordination behaviour towards the transition metal ions Fe(III), Fe(II), Co(II), Ni(II), Cu(II), Zn(II), Cd(II) and UO(2)(II) was studied. The structures of the isolated products are proposed based on elemental analyses, IR, UV-vis, (1)H NMR, mass spectra, reflectance, magnetic susceptibility measurements and thermogravimetric analysis (TGA). The hyperfine interactions in the isolated complex compounds were studied using 14.4keV gamma-ray from radioactive (57)Co (M?ssbauer spectroscopy). The data show that the ligand are coordinated to the metal ions via the sulfonamide O and deprotonated NH atoms in an octahedral manner. The H(4)L ligand forms complexes of the general formulae [(MX(z))(2)(H(2)L)H(2)O)(n)] and [(FeSO(4))(2) (H(4)L) (H(2)O)(4)], where X=NO(3) in case of UO(2)(II) and Cl in case of Fe(III), Co(II), Ni(II), Cu(II), Zn(II) and Cd(II). The molar conductance data show that the complexes are non-electrolytes. The thermal behaviour of the complexes was studied and different thermodynamic parameters were calculated using Coats-Redfern method. Most of the prepared complexes showed high bactericidal activity and some of the complexes show more activity compared with the ligand and standards.     

Molecular and electronic structures of bis(pyridine-2,6-diimine)metal complexes [ML2](PF6)n (n = 0, 1, 2, 3; M = Mn, Fe, Co, Ni, Cu, Zn)

A series of mononuclear, octahedral first-row transition metal ion complexes mer-[M(II)L0(2)](PF6)2 containing the tridentate neutral ligand 2,6-bis[1-(4-methoxyphenylimino)ethyl]pyridine (L0) and a Mn(II), Fe(II), Co(II), Ni(II), Cu(II), or Zn(II) ion have been synthesized and characterized by X-ray crystallography. Cyclic voltammetry and controlled potential coulometry show that each dication (except those of Cu(II) and Zn(II)) can be reversibly one-electron-oxidized, yielding the respective trications [M(III)L0(2)]3+, and in addition, they can be reversibly reduced to the corresponding monocations [ML2]+ and the neutral species [ML2]0 by two successive one-electron processes. [MnL2]PF6 and [CoL2]PF6 have been isolated and characterized by X-ray crystallography; their electronic structures are described as [Mn(III)L1(2)]PF6 and [Co(I)L0(2)]PF6 where (L1)1- represents the one-electron-reduced radical form of L0. The electronic structures of the tri-, di-, and monocations and of the neutral species have been elucidated in detail by a combination of spectroscopies: UV-vis, NMR, X-band EPR, Mossbauer, temperature-dependent magnetochemistry. It is shown that pyridine-2,6-diimine ligands are noninnocent ligands that can be coordinated to transition metal ions as neutral L0 or, alternatively, as monoanionic radical (L1)1-. All trications are of the type [M(III)L0(2)]3+, and the dications are [M(II)L0(2)]2+. The monocations are described as [Mn(III)L1(2)]+ (S = 0), [Fe(II)L0L1]+ (S = 1/2), [Co(I)L0(2)]+ (S = 1), [Ni(I)L0(2)]+ (S = 1/2), [Cu(I)L0(2)]+ (S = 0), [Zn(II)L1L0]+ (S = 1/2) where the Mn(II) and Fe(II) ions are low-spin-configurated. The neutral species are described as [Mn(II)L1(2)]0, [Fe(II)L1(2)]0, [Co(I)L0L1]0, [Ni(I)L0L1]0, and [Zn(II)L1(2)]0; their electronic ground states have not been determined.     

Mononuclear and polynuclear chelates of picolinoyldithiocarbazate

Mononuclear and polynuclear chelates of potassium picolinoyldithiocarbazate (KHPcDC) with Mn(II), Fe(ll1), Fe(II), Co(Il), Ni(II), Cu(II), Zn(II), Cd(II), Hg(II), Pd(II) and U(VI)O2 have been prepared and characterized by chemical and thermal (TG, DTG, DTA) analyses, molar conductivities, spectral (UV-Visible, IR, NMR, ESR) and magnetic moment measurements. The molar conductivities of the complexes lie in the non-electrolyte range whilst KHPcDC is a 1:1 electrolyte. Changes in selected vibrational absorption of the ligand upon coordination indicate that KHPcDC behaves as monoanionic and coordinates in a bidentate, tridentate and/or bridging tetradentate manner. Trans-form structure is proposed for [Pd(HPcDC)2] x 2H20 and [Cd(HPcDC)2] complexes on the basis of NMR data. An octahedral structure is proposed for Fe(III), Fe(II) and Ni(II) complexes, a square-planar structure for Co(II) and Pd(II) complexes and a tetragonally distorted octahedral structure for the Cu(II) chelate on the basis of spectroscopic and magnetic data. The ligand field parameters (B, Dq, beta) for the Fe(III) and Ni(II) chelates were calculated. TG, DTG and DTA studies support the different modes of chelation of KHPcDC. The solid metal acetate chelates have a unique decomposition exotherm profile which can be used as a rapid and sensitive tool for the detection of acetate-containing complexes.     

Uranyl binary and ternary chelates of tenoxicam Synthesis, spectroscopic and thermal characterization of ternary chelates of tenoxicam and alanine with transition metals

Ternary Fe(III), Co(II), Ni(II), Cu(II), Zn(II) and UO(2)(II) chelates with tenoxicam (Ten) drug (H(2)L(1)) and dl-alanine (Ala) (HL(2)) and also the binary UO(2)(II) chelate with Ten were studied. The structures of the chelates were elucidated using elemental, molar conductance, magnetic moment, IR, diffused reflectance and thermal analyses. UO(2)(II) binary chelate was isolated in 1:2 ratio with the formula [UO(2)(H(2)L)(2)](NO(3))(2). The ternary chelates were isolated in 1:1:1 (M:H(2)L(1):L(2)) ratios and have the general formulae [M(H(2)L(1))(L(2))(Cl)(n)(H(2)O)(m)].yH(2)O (M=Fe(III) (n=2, m=0, y=2), Co(II) (n=1, m=1, y=2) and Ni(II) (n=1, m=1, y=3)); [M(H(2)L(1))(L(2))](X)(z).yH(2)O (M=Cu(II) (X=AcO, z=1, y=0), Zn(II) (X=AcO, z=1, y=3) and UO(2)(II) (X=NO(3), z=1, y=2)). IR spectra reveal that Ten behaves as a neutral bidentate ligand coordinated to the metal ions via the pyridine-N and carbonyl-O groups, while Ala behaves as a uninegatively bidentate ligand coordinated to the metal ions via the deprotonated carboxylate-O and amino-N. The magnetic and reflectance spectral data confirm that all the chelates have octahedral geometry except Cu(II) and Zn(II) chelates have tetrahedral structures. Thermal decomposition of the chelates was discussed in relation to structure and different thermodynamic parameters of the decomposition stages were evaluated.     

Ligational,DFT modeling and biological properties of some new metal complexes with 3-(bromoacetyl)coumarin and 1,10-phenanthroline

The synthesis and characterization of Mn (II), Fe (II), Co (II), Ni (II), Cu (II) and Zn (II) complexes with 3-(bromoacetyl)coumarin (BAC) in presence of 1,10-phenanthroline (Phen) were reported and described by elemental analysis, molar conductivity, FT-IR, UV–Vis and effective magnetic moments. TG and DTG have been applied to study the decomposition mechanisms for BAC, Phen and their complexes. The analytical results and spectral studies showed that BAC and Phen act as bidentate ligands via oxygen of α, β-unsaturated ketone and oxygen of lactone carbonyl of coumarin and two pyridyl nitrogen atoms of Phen. Octahedral geometries have been proposed for all complexes and the kinetic parameter (E*, ΔH*, ΔS* and ΔG*) were calculated using Coats-Redfern (CR) and Horowitz-Metzeger (HM) methods. DFT calculations (bond lengths, bond angles, total energy, heat of formation, dipole moment and the lowest energy model structures) have been determined. The antibacterial activities for synthesized complexes were assayed against some selected bacterial and the complexes displayed a very highly significant against L. monocytogens.     

Synthesis, characterization and properties of some divalent metal(II) complexes: their electrochemical, catalytic, thermal and antimicrobial activity studies

In this study, we synthesized the amine compound 2-(2-aminoethyliminomethyl)phenol (H(3)A) as the starting material, and then we prepared the polydentate Schiff base ligands from the reactions of the amine compound (H(3)A) with phtaldialdehyde (H(2)L), 4-methyl-2,6-di-formlyphenol (H(3)L(1)) and 4-t-butyl-2,6-di-formylphenol (H(3)L(2)) in the ethanol solution. Moreover, the complexes Cd(II), Cu(II), Co(II), Ni(II), Zn(II) and Sn(II) of the ligands H(2)L, H(3)L(1) and H(3)L(2) have been prepared. All compounds have been characterized by the analytical and spectroscopic methods. In addition, the magnetic susceptibility and molar conductance measurements have been made. The catalytic properties of the mono- and binuclear Co(II) and Cu(II) complexes have been studied on the 3,5-di-tert-butylcatechol (3,5-DTBC) and ascorbic acid (aa) as a substrate. The oxidative C-C coupling properties of the Co(II) and Cu(II) complexes have been investigated on the sterically hindered 2,6-di-tert-butylphenol (dtbp). The antimicrobial activity properties of the ligands and their mono- and binuclear complexes have been studied against the bacteria and fungi. The results have been compared to the antibacterial and fungi drugs. The TGA curves show that the decomposition takes place in three steps for all complexes. Electrochemical properties of the complexes Cu(II) and Ni(II) have been investigated for the first time in acetonitrile by cyclic voltammetry.     

Synthesis,characterization and antimicrobial activity of homodinuclear complexes derived from 2,6- bis [3′-methyl- 2′-carboxamidyliminomethyl(6′,7′)benzindole]-4-methylphenol,an end-off compartmental ligand

End-off compartmental pentadentate Schiff base, 2,6-bis[3′-methyl-2′-carboxamidyliminomethyl(6′,7′)benzindole]-4-methylphenol is synthesized and characterized by 2D NMR experiments and mass spectral techniques. The homodinuclear phenalato bridged end-off compartmental Schiff-base complexes Cu(II), Co(II), Ni(II), Mn(II), Fe(III), VO(IV), Zn(II), Cd(II) and Hg(II) have been prepared by the template method using the precursors 2,6-diformyl-4-methylphenol, 3-methyl(6′,7′)-2-benzindolehydrazide and metal chlorides in 1?:?2?:?2 ratio. The complexes are characterized by IR, NMR, UV-vis, FAB-mass, ESR and TGA techniques. Ni(II), Mn(II) and Fe(III) complexes have octahedral geometry, whereas the Cu(II), Co(II), VO(IV), Zn(II), Cd(II) and Hg(II) complexes have square pyramidal geometry. Low magnetic moment values for Cu(II), Co(II), Ni(II), Mn(II), Fe(III) and VO(IV) complexes indicate antiferromagnetic spin-exchange interaction between two metal centers. The metal complexes have been screened for their antibacterial activity against Escherichia coli and Staphyloccocus aureus and antifungal activity against Aspergillus niger and Fusarium oxysporum.     

Structural, spectroscopic and thermal characterization of 2-tert-butylaminomethylpyridine-6-carboxylic acid methylester and its Fe(III), Co(II), Ni(II), Cu(II), Zn(II) and UO(2)(II) complexes

Fe(III), Co(II), Ni(II), Cu(II), Zn(II) and UO(2)(II) complexes with the ligand 2-tert-butylaminomethylpyridine-6-carboxylic acid methylester (HL(2)) have been prepared and characterized by elemental analyses, molar conductance, magnetic moment, thermal analysis and spectral data. 1:1 M:HL(2) complexes, with the general formula [M(HL(2))X(2)].nH(2)O (where M = Co(II) (X = Cl, n = 0), Ni(II) (X = Cl, n = 3), Cu(II) (grey colour, X = AcO, n = 1), Cu(II) (yellow colour, X = Cl, n = 0) and Zn(II) (X = Br, n = 0). In addition, the Fe(III) and UO(2)(II) complexes of the type 1:2 M:HL(2) and with the formulae [Fe(L(2))(2)]Cl and [UO(2)(HL(2))(2)](NO(3))(2) are prepared. From the IR data, it is seen that HL(2) ligand behaves as a terdentate ligand coordinated to the metal ions via the pyridyl N, carboxylate O and protonated NH group; except the Fe(III) complex, it coordinates via the deprotonated NH group. This is supported by the molar conductance data, which show that all the complexes are non-electrolytes, while the Fe(III) and UO(2)(II) complexes are 1:1 electrolytes. IR and H1-NMR spectral studies suggest a similar behaviour of the Zn(II) complex in solid and solution states. From the solid reflectance spectral data and magnetic moment measurements, the complexes have a trigonal bipyramidal (Co(II), Ni(II), Cu(II) and Zn(II) complexes) and octahedral (Fe(III), UO(2)(II) complexes) geometrical structures. The thermal behaviour of the complexes is studied and the different dynamic parameters are calculated applying Coats-Redfern equation.     

Synthesis and characterization of some pyrimidine, purine, amino acid and mixed ligand complexes

Mn(II), Fe(III), Co(II), Ni(II), Cu(II), Zn(II) and Cd(II) complexes of barbital, thiouracil, adenine, amino acids (methionine, lysine and alanine) and some mixed ligands were prepared and characterized by elemental analyses, IR, electronic spectra, magnetic susceptibility and ESR spectra. Coordination of the metallic centre to the oxygen and nitrogen atoms of barbital, thiouracil, amino acids and coordinate to amino group and nitrogen atom of adenine occurred. Electronic spectra and magnetic susceptibility measurements were utilized to infer the structure of the complexes which are octahedral for Mn(II), Fe(III), Co(II), Ni(II) and Cd(II) and tetrahedral for Mn(II), Cu(II), Zn(II) complexes. ESR spectra were observed for copper complexes with a d(x2)-(y2) ground state with small g(||) values indicating strong interaction between the ligands and their metal ions.