Synthesis,characterization and mass spectral studies on acrocyclic schiff base complexes of Pb(II), Zn(II) and La(III)

Six new macrocyclic complexes were synthesized by template reaction of (±)-1,4-bis(3-aminopropoxy)butane with metal(II) nitrate and 1,10-bis(2-formylphenyl)-1,4,7,10-tetraoxadecane or 1,7-bis(2-formylphenyl)-1,4,7-trioxaheptane and their structures were proposed on the basis of elemental analysis, FT-IR, UV-Vis, molar conductivity measurements, ¹H NMR and mass spectra. The metals to ligand molar ratios of the complexes were found to be 1: 1. The complexes are 1: 2 electrolytes for Pb(II) and Zn(II) complexes and 1: 3 electrolytes for La(III) as shown by their molar conductivities (Λ_m) in DMSO at 10⁻³ mol L⁻¹. Due to the existence of free ions in these complexes, such complexes are electrically conductive. The configurations of La(III) and Zn(II) complexes were proposed to probably octahedral.     

Synthesis and spectral studies of macrocyclic Pb(Ⅱ), Zn(Ⅱ), Cd(II)and La(Ⅲ) complexes derived from 1,4-bis(3-aminopropoxy)butane with metal nitrate and salicylaldehyde derivatives

Eight new macrocyclic complexes were synthesized by template reaction of 1,4-bis(3-aminopropoxy)butane with metal nitrate and 1,3-bis(2-forrnylphenyl)propane or 1,4-bis(2-formylphenyl)butane and their structures were proposed on the basis of elemental analysis, FTIR, UV-vis, molar conductivity measurements, 1H NMR and mass spectra. The metals to ligand molar ratios of the complexes were found to be 1:1. The complexes are 1:2 electrolytes for Pb(II), Zn(II) and Cd(II) complexes and 1:3 electrolytes for La(lIl) as shown by their molar conductivities (Am) in DMSO at 10-3 tool L-l. Due to the existence of free ions in these complexes,such complexes are electrically conductive. The configurations of La(Ⅲ) and Pb(U) were proposed to probably octahedral and Zn(II) and Cd(II) complexes were proposed to probably tetrahedral.     

Synthesis and characterization of novel Cd(II), Zn(II) and Ni(II) complexes with 2-quinolinecarboxaldehyde selenosemicarbazone. Crystal structure of bis(2-quinolinecarboxaldehyde selenosemicarbazonato)nickel(II)

New complexes of Cd(II), Zn(II) and Ni(II) with 2-quinolinecarboxaldehyde selenosemicarbazone (Hqasesc) were synthesized and structurally characterized. The structure of the ligand, Cd(II) and Zn(II) complexes was determined by NMR and IR spectroscopy, elemental microanalysis and molar conductivity measurements. Both complexes occur in solution in two forms, the major tetrahedral and minor octahedral. In the major Cd(II) complex one qasesc⁻ ligand is coordinated as a tridentate, the fourth coordination site being occupied by acetate, while in the major Zn(II) complex two qasesc⁻ ligands are coordinated as bidentates. In both minor complexes two qasesc⁻ ligands are coordinated as tridentates forming the octahedral geometry around the central metal ion. The only paramagnetic complex in the series is Ni(II) complex for which X-ray structure analysis was performed. The complex has the angularly distorted octahedral geometry with two qasesc⁻ ligands coordinated as tridentates, in a similar way as in the minor complexes of Cd(II) and Zn(II).     

Spectroscopic investigations and physico-chemical characterization of newly synthesized mixed-ligand complexes of 2-methylbenzimidazole with metal ions

Some mixed ligand complexes containing 2-methylbenzimidazole and thiocyanate ion were synthesized. Free ligands and their metal complexes were characterized using elemental analysis, determination of metal, magnetic susceptibility, molar conductivity, infrared, UV-VIS, and (¹H, ¹³C) NMR spectra, and X-ray structure analysis. The results suggest that the Ag(I) complex has linear geometry, Fe(II), Co(II), Ni(II), Cu(II), Zn(II), and Cd(II) have tetrahedral geometry, Pd(II) complex has square planar geometry, VO(IV) square pyramidal geometry, Pb(II) irregular tetrahedral geometry, and that the Cr(III) and Mn(II) complexes have octahedral geometry. The following general formulae were proposed for the prepared complexes: [AgBX], [CrB₃X₃], (HB)₂[MnB₂X₄] · 2B and [MB₂X₂], where B = 2-methylbenzimidazole, HB = 2-methylbenzimidazolium, X = thiocyanate ion, and M = VO(IV), Fe(II), Co(II), Ni(II), Cu(II), Zn(II), Pd(II), Cd(II), and Pb(II). Molar conductance of a 10⁻³ M solution in N,N-dimethyl formamide (DMF) indicates that all the complexes are non-electrolytes except the Mn(II) complex which is an electrolyte because the molar conductivity of its solution in DMF is high.     

Synthesis and characterization of a thioether Schiff base ligand and its metal complexes and crystal structure determination of the nickel(II) complex

Reactions of 1,2-di(o-aminophenylthio)ethane with 3-ethoxy-2-hydroxybenzaldehyde yield the new hexadentate N₂S₂O₂ donor thioether Schiff base 1,2-bis(2-((2-(thio)phenylimino)methyl)-6-ethoxyphenol)ethane (H₂L). Ni(II), Zn(II), Cd(II), and Hg(II) complexes of this ligand were prepared. Of these complexes, [NiL]·2H₂O has been structurally characterized by X-ray crystallography. The coordination geometry around Ni(II) was described as octahedral. Zn(II), Cd(II), and Hg(II) complexes and the Schiff base ligand have been characterized by CHN analyses, molar conductivity, UV–vis, FT-IR, ¹H, and ¹³C NMR spectroscopy.     

Studies of Co(II), Ni(II), Cu(II) and Cd(II) chelates with different phosphonic acids

Co(II), Ni(II), Cu(II) and Cd(II) chelates with 1-aminoethylidenediphosphonic acid (AEDP, H₄L¹), α-amino benzylidene diphosphonic acid (ABDP, H₄L²), 1-amino-2-carboxyethane-1,1-diphosphonic acid (ACEDP, H₅L³), 1,3-diaminopropane-1,1,3,3-tetraphosphonicacid (DAPTP, H₈L⁴), ethylenediamine-N,N′-bis(dimethylmethylene phosphonic)acid (EDBDMPO, H₄L⁵), O-phenylenediamine-N,N′-bis(dimethyl methylene phosphonic)acid (PDBDMPO, H₄L⁶), diethylene triamine-N,N,N′,N′,N″N″-penta(methylene phosphonic)acid (DETAPMPO, H₁₀L⁷) and diethylene triamine-N,N″-bis(dimethyl methylene phosphonic)acid (DETBDMPO, H₄L⁸) have been synthesised and were characterised by elemental and thermal analyses as well as by IR, UV–VIS, EPR and magnetic measurements. The first stage in the thermal decomposition process of these complexes shows the presence of water of hydration, the second denotes the removal of the coordinated water molecules. After the loss of water molecules, the organic part starts decomposing. The final decomposition product has been found to be the respective MO·P₂O₅. The data of the investigated complexes suggest octahedral geometry with respect to Co(II) and Ni(II) and tetragonally distorted octahedral geometry with respect to Cu(II). Antiferromagnetism has been inferred from magnetic moment data. Infrared spectral studies have been carried out to determine coordination sites.     

Synthesis and photoluminescent properties of a Schiff-base ligand and its mononuclear Zn(II), Cd(II), Cu(II), Ni(II) and Pd(II) metal complexes

Mononuclear Zn(II), Cd(II), Cu(II), Ni(II) and Pd(II) metal complexes of Schiff-base ligand(HL₁) derived from 8-acetyl-7-hydroxycoumarin and P-phenylenediamine were prepared and characterized by microanalytical, mass, UV–Vis, IR, ¹H NMR, ¹³C NMR, ESR, conductance and fluorescence studies. The measured low molar conductance values in DMSO indicate that the complexes are non-electrolytes. The structures of the solid complexes under study are established by using IR, electronic and ESR spectroscopy suggesting that Zn(II) and Ni(II) complexes are octahedral, Cd(II) complex is tetrahedral, Cu(II) and Pd(II) complexes are square planar. The ESR spectrum of the Cu(II) complex in DMSO at 298 and 150 K was recorded and its salient features are reported, it supports the mononuclear structure. The Schiff base exhibited photoluminescence originating from intraligand (π–π*) transitions. Metal-mediated enhancement is observed on complexation of HL with Zn(II) and Cd(II), whereas metal-mediated fluorescence quenching occurs in Cu(II), Ni(II) and Pd(II).     

Synthesis,characterization, electrical conductivity,and catalytic studies of some coordination polymers of salen-type schiff base

Coordination polymers of Mn(II), Fe(II), Co(II), Ni(II), Cu(II), Zn(II), and Cd(II) with the salen-type Schiff base 4,4′-bis[(N-ethanesalicylaldehydediamine-5)azo]biphenyl have been prepared and characterized by elemental analyses, IR and electronic spectra, magnetic susceptibility measurements, and thermogravimetric analysis. Thermogravimetric analysis confirms the coordination of H₂O in complexes. The ¹H NMR spectrum of ligand clearly indicates the presence of OH and azomethine groups. The octahedral geometry have been suggested for Mn(II), Fe(II), Co(II), and Ni(II) complexes, and square planar Cu((II), whereas tetrahedral is suggested for Zn(II) and Cd(II) polychelates. Thermal data have been analyzed for kinetic parameters by both Coat-Redfern and Broido methods. Solid-state dc conductivity of ligand and its polychelates was measured in their compressed pellet form over 313–413 K temperature range. Solidstate conductivity lies in the range 4.361 × 10⁻¹¹ to 7.241 × 10⁻¹⁰ Ohm⁻¹ cm⁻¹ indicating their semiconducting behavior. Oxidation of styrene with selected catalysts was tested using H₂O₂ as an oxidant.     

Transition metal complexes of Schiff base ligand based on 4,6-diacetyl resorcinol

Novel Schiff base ligand based on the condensation of 4,6-diacetyl resorcinol with 2-amino-4-methylthiazole in addition to its metal complexes with Cr (III), Mn (II), Fe (III), Co (II), Ni (II), Cu (II), Zn (II) and Cd (II) ions have been synthesized. The structure, electronic properties, and thermal behaviour of Schiff base and its metal complexes have been studied by elemental analysis, mass, ¹H NMR, IR spectra, thermal analysis, and theoretically by density function theory. The ligand acted as mononegative bidentate (NO) ligand and all complexes showed octahedral geometry except Cu (II) showed tetrahedral geometry as indicated from the spectral and magnetic studies. The Cu (II), Zn (II) and Cd (II) complexes were non electrolytes while the rest of the complexes were electrolytes. The antibacterial plus anticancer activities of the parent Schiff base and its metal complexes were screened. In addition, the molecular docking study was performed to explore the possible ways for binding to Crystal Structure of Human Astrovirus capsid protein (5ibv) receptor.     

Synthesis,characterization and biological studies of Co(II), Ni(II), Cu(II) and Zn(II) complexes with pyrral-l-histidinate

The Schiff base ligand, pyrral-l-histidinate(L) and its Co(II), Ni(II), Cu(II) and Zn(II) complexes were synthesized and characterized by elemental analysis, mass, molar conductance, IR, electronic, magnetic measurements, EPR, redox properties, thermal studies, XRD and SEM. Conductance measurements indicate that the above complexes are 1:1 electrolytes. IR data show that the ligand is tridentate and the binding sites are azomethine nitrogen, imidazole nitrogen and carboxylato oxygen atoms. Electronic spectral and magnetic measurements indicate tetrahedral geometry for Co(II) and octahedral geometry for Ni(II) and Cu(II) complexes, respectively. The observed anisotropic g values indicate the presence of Cu(II) in a tetragonally distorted octahedral environment. The redox properties of the ligand and its complexes have been investigated by cyclic voltammetry. Thermal decomposition profiles are consistent with the proposed formulations. The powder XRD and SEM studies show that all the complexes are nanocrystalline. The in vitro biological screening effects of the synthesized compounds were tested against the bacterial species, Escherichia coli, Bacillus subtilis, Pseudomonas aeruginosa and Staphylococcus aureus; fungal species, Aspergillus niger, Aspergillus flavus and Candida albicans by the disc diffusion method. The results indicate that complexes exhibit more activity than the ligand. The nuclease activity of the ligand and its complexes were assayed on CT DNA using gel electrophoresis in the presence and absence of H₂O₂.     

Template synthesis and physicochemical studies of 14-membered hexaazmacrocyclic complexes with Co(II), Ni(II), Cu(II) and Zn(II): a comparative spectroscopic approach on DNA binding with Cu(II) and Ni(II) complexes

A new series of 14-membered pendant arm hexaazamacrocyclic complexes of the type [MLX₂] · [M = Co(II), Ni(II), Cu(II) or Zn(II) for X = Cl; Co(II), Ni(II), Cu(II) or Zn(II) for X = NO₃] has been synthesized by metal template condensation of 1,2-phenylenediamine and 1,4-phenylenediamine with formaldehyde in methanol. The mode of bonding and overall geometry of these complexes have been deduced by elemental analyses, molar conductance values, FT-IR, ¹H-NMR, ¹³C-NMR, EPR, ESI-mass and UV–VIS along with magnetic measurement studies. The fluorescence and UV–VIS studies revealed a significant binding ability to DNA.     

Spectral,thermal, electrochemical,biological and DFT studies on nanocrystalline Co(II), Ni(II), Cu(II) and Zn(II) complexes with a tridentate ONO donor Schiff base ligand

Co(II), Ni(II), Cu(II) and Zn(II) Schiff base complexes derived from 3-hydrazinoquionoxaline-2-one and 1,2-diphenylethane-1,2-dione were synthesized. The compounds were characterized by elemental analyses, molar conductance, magnetic susceptibility measurements, FTIR, UV–vis, ¹H NMR, ¹³C NMR, ESR, and mass spectral studies. Thermal studies of the ligand and its metal complexes were also carried out to determine their thermal stability. Octahedral geometry has been assigned for Co(II), Ni(II), and Zn(II) complexes, while Cu(II) complex has distorted octahedral geometry. Powder XRD study was carried out to determine the grain size of ligand and its metal complexes. The electrochemical behavior of the synthesized compounds was investigated by cyclic voltammetry. For all complexes, a 2 : 1 ligand-to-metal ratio is observed. The ligand and its metal complexes were screened for their activity against bacterial species such as E. coli, P. aeruginosa, and S. aureus and fungal species such as A. niger, C. albicans, and A. flavus by disk diffusion method. The DNA-binding of the ligand and its metal complexes were investigated by electronic absorption titration and viscosity measurement studies. Agarose gel electrophoresis was employed to determine the DNA-cleavage activity of the synthesized compounds. Density functional theory was used to optimize the structure of the ligand and its Zn(II) complex.     

Manganese(II), cobalt(II) and nickel(II) complexes with 2-phenyl-3-(benzylamino)-1,2-dihydroquinazolin-4(3H)-one,pseudohalides and some bidentate N-donor ligands

Some mixed ligand complexes of the type [M(L)(en or phen)(X)₂]; where M = Mn(II), Co(II) or Ni(II); L = 2-phenyl-3-(benzylamino)-1,2-dihydroquinazolin-4(3H)-one; en = ethylenediamine, phen = 1,10-phenanthroline; X = N₃ ⁻ or NCS⁻ have been prepared. All the complexes were characterized by physico-chemical, spectroscopic and thermal studies. On the basis of electronic spectra and magnetic susceptibility measurements, an octahedral geometry has been proposed for all the complexes. The phen complexes are thermally more stable than the en complexes. The electrochemical behavior of the Ni(II) complexes showed that the complexes of phen are reduced at more positive potential compared to the corresponding en complexes.     

Synthesis and spectral studies of new macrocyclic Schiff base Cu(II), Ni(II), Cd(II), Zn(II), Pb(II), and La(III) complexes containing pyridine head unit

1,6-Bis(2-formylphenyl) hexane (I) was derived from 1,6-dibromohexane with salicylaldehyde and K₂CO₃ and the ligand (L) was derived from compound I and 2,6-diaminopyridine. Then, the Cu(II), Ni(II), Pb(II), Zn(II), Cd(II), and La(III) complexes with L were synthesized by the reaction of this ligand and Cu(NO₃)₂ · 3H₂O, Ni(NO₃)₂ · 6H₂O, Pb(NO₃)₂, Zn(NO₃)₂ · 6H₂O, Cd(NO₃)₂ · 6H₂O, and La(NO₃)₃ · 6H₂O, respectively. The ligand and its metal complexes were characterized by elemental analysis, IR, ¹H and ¹³C NMR, UV-Vis spectra, magnetic susceptibility, conductivity measurements, and mass spectra. All complexes are diamagnetic and the Cu(II) complex is binuclear. The article is published in the original.     

Synthesis,spectral, thermal,and magnetic studies of cobalt(II), nickel(II), copper(II), zinc(II), and cadmium(II) complexes with N2O2 donor groups

A new Schiff base ligand was prepared by condensation of 2-hydroxy-4-methoxybenzaldehyde with 1,2-propanediamine. The ligand and its metal complexes were characterized by elemental analysis, FT-IR, ¹H and ¹³C NMR, magnetic moment, molar conductance, UV-Vis, SEM and thermal analysis (TGA). The molar conductance measurements indicated that all the metal complexes were non-electrolytes. IR spectra showed that ligand (L) behaves as a neutral tetradentate ligand and binds to the metal ions by the two azomethine nitrogen atoms and two phenolic oxygen atoms. The electronic absorption spectra and magnetic susceptibility measurements indicated square planar geometry for the Ni(II) and Cu(II) complexes while other metal complexes showed tetrahedral geometry. Also the surface morphology of the complexes was studied by SEM.     

Determination of trace Pb(Ⅱ), Cd(Ⅱ) and Zn(Ⅱ) using differential pulse stripping voltammetry without Hg modification

In this work,we reported a simultaneous determination approach for Pb(II),Cd(II)and Zn(II)atμg L 1concentration levels using differential pulse stripping voltammetry on a bismuth film electrode(BiFE).The BiFE could be prepared in situ when the sample solution contained a suitable amount of Bi(NO)3,and its analytical performance was evaluated for the simultaneous determination of Pb(II),Cd(II)and Zn(II)in solutions.The determination limits were found to be 0.19μg L 1for Zn(II),and0.28μg L 1for Pb(II)and Cd(II),with a preconcentration time of 300 s.The BiFE approach was successfully applied to determine Pb(II),Cd(II)and Zn(II)in tea leaf and infusion samples,and the results were in agreement with those obtained using an atomic absorption spectrometry approach.Without Hg usage,the in situ preparation for BiFE supplied a green and acceptability sensitive method for the determination of the heavy metal ions.     

Complexes of cobalt(II), nickel(II), copper(II), cadmium(II), and mercury(II) with tetradentate Schiff base ligands

Summary A series of metal complexes with three new tetradentate Schiff bases derived from benzoin and benzil withc-toluidine and benzil with diaminoethane have been prepared and characterised by physical and chemical methods. The modes of bonding of the ligands with the metal ions have been proposed. Electronic spectra and room temperature magnetic moment values suggest octahedral geometry for the Co^II and Ni^II complexes, whereas the Hg^II and Cd^II complexes have tetrahedral geometry. The Cu^II complexes are square planar. Apart from the complexes of the Schiff bases derived from benzoin, all the other complexes have high molar conductance values suggesting them to be electrolytes. The complexes have been screened against some fungal pathogens.     

Heteronuclear complexes of oxorhenium(V) with Fe(III), Co(II), Ni(II), Cu(II), Cd(II) and UO2(VI) and their biological activities

Heteronuclear complexes containing oxorhenium(V), with Fe(III), Co(II), Ni(II), Cu(II), Cd(II) and UO₂(VI) ions were prepared by the reaction of the complex ligands [ReO(HL¹)(PPh₃)(OH₂)Cl]Cl (a) and/or [ReO(H₂L²)(PPh₃)(OH₂)Cl]Cl (b), where H₂L¹?=?1-(2-hydroxyphenyl)butane-1,3-dione-3-(5,6-diphenyl-1,2,4-triazine-3-ylhydrazone) and H₃L²?=?1-(2-hydroxyphenyl)butane-1,3-dione-3-(1H-benzimidazol-2-ylhydrazone), with transition and actinide salts. Heterodinuclear complexes of ReO(V) with Fe(III), Co(II), Ni(II), Cu(II) and Cd(II) were obtained using a 1?:?1 mole ratio of the complex ligand and the metal salt. Heterotrinuclear complexes were obtained containing ReO(V) with UO₂(VI) and Cu(II) using 2?:?1 mole ratios of the complex ligand and the metal salts. The complex ligands a and b coordinate with the heterometal ion via a nitrogen of the heterocyclic ring and the nitrogen atom of the C=N⁷ group. All transition metal cations in the heteronuclear complexes have octahedral configurations, while UO₂(VI)?complexes have distorted dodecahedral geometry. The structures of the complexes were elucidated by IR, ESR, electronic and ¹H NMR spectra, magnetic moments, conductance and TG-DSC measurements. The antifungal activities of the complex ligands and their heteronuclear complexes towards Alternaria alternata and Aspergillus niger showed comparable behavior with some well-known antibiotics.     

Synthesis and characterization of copper(II), cobalt(II), nickel(II), and iron(III) complexes with two diamine Schiff bases and catalytic reactivity of a chiral diamine cobalt(II) complex

New transition metal complexes of Co(II), Cu(II), Ni(II), and Fe(III) of the ligands 6,6′-(1E,1′E)-(4,5-dimethyl-1,2-phenylene)bis(azan-1-yl-1-ylidene)bis(methan-1-yl-1-ylidene)bis(7-hydroxy-5-methoxy-2-methyl-4H-chromen-4-one) H₂L¹ and 6,6’-(1E,1′E)-cyclohexane-1,2-diylbis(azan-1-yl-1-ylidene)bis(methan-1-yl-1-ylidene)bis(7-hydroxy-5-methoxy-2-methyl-4H-chromen-4-one) H₂L² have been prepared and characterized using physio-chemical and spectroscopic methods. The results obtained for the complexes indicated that the geometries of the metal centres are either square planar or octahedral. Cyclopropanation reactions of unactivated olefins by ethyldiazoacetate (EDA) in the presence of [L¹Cu]·H₂O, [L²Cu]·2H₂O and [L²*Co]·2H₂O as catalysts were examined. The results showed that only [L²*Co]·2H₂O can act as a catalyst for the cyclopropanation reaction of unactivated olefins with very high selectivity (up to 99% based on EDA).     

Synthesis,structural characterization,and antibacterial studies of a tetradentate macrocyclic ligand and Its Co(II), Ni(II), and Cu(II) complexes

A novel macrocyclic tetradentate ligand 1,5,8,12-tetraaza-2,4,9,11-tetraphenyl-6,7:13,14-dibenzocyclohexadeca- 1,4,8,11-tetraene (L) has been synthesized. Cobalt(II), nickel(II), and copper(II) complexes of this ligand have been prepared and characterized by elemental analysis, molar conductance measurements, magnetic susceptibitity measurements, and mass, IR, electronic, and ESR spectral studies. The molar conductance measurements correspond to a nonelectrolytic nature for all the complexes, which can be formulated as [M(L)X₂] (where M = Co(II), Ni(II), and Cu(II); X = Cl⁻ and NO₃⁻). On the basis of IR, electronic, and ESR spectral studies, an octahedral geometry has been assigned to the Co(II) and Ni(II) complexes, whereas a tetragonal geometry was found for the Cu(II) complexes. The investigated compounds and uncomplexed metal salts and the ligands were tested against bacterial species like Sarcina lutea, Escherchia coli, and Staphylococcus aureus. The metal complexes have higher activity than the free ligand and metal salts. The text was submitted by the authors in English.