Preparation and characterization of binuclear CuII complexes derived from diamines and dialdehydes

New macrocyclic complexes were synthesized by template reaction of 1,7-bis(2-formylphenyl)-1,4,7-trioxaheptane, 1,4-bis(2-carboxyaldehydephenoxy)butane or 1,3-bis(2-carboxyaldehydephenoxy)propane with 1,4-bis(2-aminophenoxy)butane, 1,3-bis(2-aminophenoxy)butane, 1,4-bis(4-chloro-2-aminophenoxy)butane or 1,3-bis(4-chloro-2-aminophenoxy)butane and Cu(NO₃)₂ ·?3H₂O or Cu(ClO₄)₂ ·?6H₂O, respectively. The complexes have been characterized by elemental analysis, IR, ¹H and ¹³C NMR, UV–Vis spectra, magnetic susceptibility, conductivity measurements and mass spectra. All complexes are diamagnetic and binuclear.     

Synthesis and spectral studies of macrocyclic Cu(II) complexes by reaction of various diamines,copper(II) perchlorate and 1,4-bis(2-carboxyaldehyde phenoxy)butane

Six macrocyclic complexes, were synthesized by reaction of 1,4-bis(2-carboxyaldehyde phenoxy)butane and various amines and their copper(II) perchlorate complexes were synthesized by template effect reaction of 1,4-bis(2-carboxyaldehyde phenoxy)butane, Cu(ClO₄)₂?·?6H₂O and amines. The metal-to-ligand ratios were found to be 1?:?1. Cu(II) metal complexes are 1?:?2 electrolytes as shown by their molar conductivities (Λ_M) in DMF (dimethyl formamide) at 10^?3?M. The Cu(II) complexes are proposed to be square planar based on elemental analysis, FT–IR, UV–Vis, magnetic susceptibility measurements, molar conductivity measurements, and mass spectra.     

Copper(II), Cobalt(II), and Nickel(II) Complexes of two Novel Pyridine‐derived Macrocyclic Ligands bearing o‐ and pNitrobenzyl Pendant Groups

The pendant‐armed ligands L¹ and L² were synthesized by N‐alkylation of the four secondary amine groups of the macrocyclic precursor L using o‐nitrobenzylbromide (L¹) and p‐nitrobenzylbromide (L²). Nitrates and perchlorates of Cu^II, Ni^II and Co^II were used to synthesize the metal complexes of both ligands and the complexes were characterized by microanalysis, MS‐FAB, conductivity measurements, IR and UV‐Vis spectroscopy and magnetic studies. The crystal structures of L¹, [CuL¹](ClO₄)₂·CH₃CN·H₂O, [CuL²](ClO₄)₂·6CH₃CN, [CuL²][Cu(NO₃)₄]·5CH₃CN·0.5CH₃OH and [NiL²](ClO₄)₂·3CH₃CN·H₂O were determined by single crystal X‐ray crystallography. These structural analysis reveal the free ligand L¹, three mononuclear endomacrocyclic complexes {[CuL¹](ClO₄)₂·CH₃CN·H₂O, [CuL²](ClO₄)₂·6CH₃CN and [NiL²](ClO₄)₂·3CH₃CN·H₂O} and one binuclear complex {[CuL²][Cu(NO₃)₄]·5CH₃CN·0.5CH₃OH} in which one of the metals is in the macrocyclic framework and the other metal is outside the ligand cavity and coordinated to four nitrate ions.     

Synthesis and characterization of new macrocyclic Schiff base derived from 2,6-diaminopyridine and 1,7-bis(2-formylphenyl)-1,4,7-trioxaheptane and its Cu(II), Ni(II), Pb(II), Co(III) and La(III) complexes

A new macrocyclic ligand, 1,3,5-triaza-2,4:7,8:16,17-tribenzo-9,12,15-trioxacyclooktadeca-1,5-dien (L) was synthesized by reaction of 2,6-diaminopyridine and 1,7-bis(2-formylphenyl)-1,4,7-trioxaheptane. Then, its Cu(II), Ni(II), Pb(II), Co(III) and La(III) complexes were synthesized by template effect by reaction of 2,6-diaminopyridine and 1,7-bis(2-formylphenyl)-1,4,7-trioxaheptane and Cu(NO₃)₂ · 3H₂O, Ni(NO₃)₂ · 6H₂O, Pb(NO₃)₂, Co(NO₃)₂ · 6H₂O, La(NO₃)₃ · 6H₂O, respectively. The ligand and its metal complexes have been characterized by elemental analysis, IR, ¹H and ¹³C NMR, UV–Vis spectra, magnetic susceptibility, thermal gravimetric analysis, conductivity measurements, mass spectra and cyclic voltammetry. All complexes are diamagnetic and Cu(II) complex is binuclear. The Co(II) was oxidized to Co(III). The comparative electrochemical studies show that the nickel complex exhibited a quasi-reversible one-electron reduction process while copper and cobalt complexes gave irreversible reduction processes in DMSO solution.     

The syntheses and magnetic properties of a series of heterospin [LnIIICuII 4] pentanuclear complexes

Twelve oxamide-bridged Ln(III)–Cu(II) heteropentanuclear complexes Ln[Cu(PMoxd)]₄(ClO₄)₃ · 5H₂O (Ln = La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Yb, and PMoxd = the N,N′-Bi(α-pyridylmethyl)-oxamide dianion) and 12 oxamide-bridged Ln(III)–Cu(II) heteropentanuclear complexes with the formula of Ln[Cu(PEoxd)]₄(ClO₄)₃ · 5H₂O (PEoxd = the N,N′-Bi(α-pyridylethyl)-oxamide dianion) were synthesized and characterized. The magnetic properties of Gd[Cu(PMoxd)]₄(ClO₄)₃ · 5H₂O (7) and Gd[Cu(PEoxd)]₄(ClO₄)₃ · 2H₂O (19) show that there are ferromagnetic interactions between Gd(III) and Cu(II) in the complexes with J _Cu–Gd = 1.38 cm^?1 and J _Cu–Gd = 1.00 cm^?1, respectively. Fluorescent quenching phenomena for Eu[Cu(PMoxd)]₄(ClO₄)₃ · 5H₂O (6) and Tb[Cu(PMoxd)]₄(ClO₄)₃ · 5H₂O (8) were also observed.     

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,crystal structure and magnetic properties of a new binuclear copper(II)-copper(II) complex of a macrocyclic oxamide

The binuclear metal complex [Cu(μ-exoO₂)cyclamCu(bpy)](ClO₄)₂·H₂O (bpy?=?2,2′-bipyridine and (exoO₂)cyclam?=?1,4,8,11-tetraazacyclotradecanne-2,3-dione) has been synthesized and characterized by single-crystal X-ray analysis and spectroscopic and magnetic measurements. The structure consists of homobinuclear [Cu(μ-exoO₂)cyclamCu(bpy)]²⁺ cations, a weakly coordinated water molecule and perchlorate ions. In each binuclear unit, Cu1, coordinated by four nitrogen atoms of the macrocyclic organic ligand is connected to Cu2 via the exo-cis oxygen atoms of the macrocyclic ligand with Cu···Cu separations of 5.151?Å; Cu2 assumes square-pyramidal geometry. Magnetic properties measured at 2–300?K show antiferromagnetic exchange between adjacent copper(II) ions.     

Synthesis and spectral characterization of macrocyclic Schiff base by reaction of 2,6-diaminopyridine and 1,4- bis (2-carboxyaldehydephenoxy)butane and its CuII, NiII, PbII, CoIII and LaIII complexes

A new macrocyclic ligand, 1,3,5-triaza-2,4:7,8:15,16-tribenzo-9,15-dioxacycloheptadeca-1,5-diene (L) was synthesized by reaction of 2,6-diaminopyridine with 1,4-bis(2-carboxyaldehydephenoxy)butane. Then, its Cu^II, Ni^II, Pb^II, Co^III and La^III complexes were synthesized by the template effect by reaction of 2,6-diaminopyridine and 1,4-bis (2-carboxyaldehydephenoxy)butane and Cu(NO₃)₂ · 3H₂O, Ni(NO₃)₂ · 6H₂O, Pb(NO₃)₂, Co(NO₃)₂ · 6H₂O, La (NO₃)₃ · 6H₂O, respectively. The ligand and its metal complexes were characterized by elemental analysis, IR, ¹H- and ¹³C-n.m.r., UV-vis spectra, magnetic susceptibility, thermal gravimetric analysis, conductivity measurements and mass spectra. All complexes are diamagnetic and the Cu^II complex is binuclear. The Co^II complex was oxidised to Co^III.     

Synthesis and characterization of a new macrocyclic Schiff base derived from 2,6-diaminopyridine and 1,10-bis(2-formylphenyl)-1,4,7,10-tetraoxadecane and its Cu(II), Ni(II), Pb(II), Co(III) and La(III) complexes

A new macrocyclic ligand, 1,3,5-triaza-2,4:7,8:19,20-tribenzo-9,12,15,18-tetraoxacyclounkosa-1,5-diene (L) was synthesized by reaction of 2,6-diaminopyridine and 1,10-bis(2-formylphenyl)-1,4,7,10-tetraoxadecane. Then, its Cu^II, Ni^II, Pb^II, Co^III and La^III complexes were synthesized by the template effect by reaction of 2,6-diaminopyridine and 1,10-bis(2-formylphenyl)-1,4,7,10-tetraoxadecane and Cu(NO₃)₂· 3H₂O, Ni(NO₃)₂· 6H₂O, Pb(NO₃)₂, Co(NO₃)₂· 6H₂O, La(NO₃)₃·6H₂O respectively. The ligand and its metal complexes have been characterized by elemental analysis, IR, ¹H and ¹³C NMR, u.v–vis spectra, magnetic susceptibility, conductivity measurements and mass spectra. All complexes are diamagnetic and the Cu^II complex is binuclear. The Co^III complex was oxidized to Co^III.     

Komplexe offenkettiger und cyclischer Sulfoxide. Kristallstrukturen von CuII-, NiII-, PdII- und PtII-Komplexen des 3-Thia-1,5-diaminopentan-S-oxids und des 1-Thia-4,7-diazacyclononan-S-oxids

Complexes of Acyclic and Cyclic Sulfoxides. The Crystal Structures of Cu^II, Ni^II, Pd^II and Pt^II Complexes of 3-Thia-1,5-diaminopentane-S-oxide and 1-Thia-4,7-diazacyclononane-S-oxide The macrocyclic ligand 1-thia-4,7-diazacyclononane-S-oxide (tasno) and the analogue acyclic ligand 3-thia-1,5-diaminopentane-S-oxide (daeso) have been prepared. Their reaction with the respective metal salts yielded the following compounds: [Ni(daeso)₂](PF₆)₂ ( 1 ), [Pd(daeso)₂](PF₆)₂ ( 2 ), [Cu(daeso)₂]Cl₂ ( 3 ), [Cu(daeso)₂](ClO₄)₂ ( 4 ), [Cu(tasno)₂]Br· 2 H₂O ( 5 ), [Ni(tasno)₂](ClO₄)₂ ( 6 ), [Pd(tasno)₂]Br· H₂O ( 7 ) and [Pt(tasno)₂]Br· H₂O ( 8 ). The structures of 1 and 4 – 8 have been determined by X-ray crystallography. In 4 and 5 Cu^II shows a Jahn-Teller distorted trans-N₄O₂ coordination, with O-donation of the sulfoxide group. O-donation of the SO-groups occurs also in the Ni^II complexes 1 and 6 , giving a cis-N₄O₂ coordination sphere in 1 and a trans-N₄O₂ sphere in 6 . In 7 the sulfur atom of the SO group is weakly interacting with the metal center in apical positions, whereas in 8 the sulfoxide group is directed away from the Pd^II ion. Metal to ligand distances in the complexes of tasno are shorter than in the complexes of daeso.     

Novel one-dimensional polymeric Cu(II) complexes via Cu(II)-assisted hydrolysis of the 2,4-bis(3,5-dimethyl-1H-pyrazol-1-yl)-6-methoxy-1,3,5-triazine pincer ligand: Synthesis,structure, and antimicrobial activities

Two unexpected one-dimensional coordination polymers, [Cu(PT)(H₂O)Cl]_n 1 and [Cu₂(BPT)(ClO₄)₃(H₂O)₄]_n·2nH₂O 2 , of symmetrical triazine-based ligands were synthesized by Cu(II)-mediated hydrolysis of the 2,4-bis(3,5-dimethyl-1H-pyrazol-1-yl)-6-methoxy-1,3,5-triazine ( MBPT ) pincer ligand. The reaction of Cu(ClO₄)₂·6H₂O with MBPT proceeded via hydrolysis of the methoxy group to produce the dicompartmental 4,6-bis(3,5-dimethyl-1H-pyrazol-1-yl)-1,3,5-triazin-2(1H)-one ligand ( HBPT ) that then undergoes in situ complexation with Cu(II) to afford 2 . In case of CuCl₂, the reaction proceeds further with C–N cleavage of one pyrazolyl unit leading to the formation of 6-(3,5-dimethyl-1H-pyrazol-1-yl)-1,3,5-triazine-2,4(1H,3H)-dione ligand ( HPT ) that also undergoes in situ complexation with Cu(II) affording 1 . The role of Cu(II) is to increase the Lewis acid reactivity of the water molecule where similar hydrolytic reactions for MBPT were observed in acidic medium in presence of an aqueous HCl (1:1 v/v) solution. The molecular and supramolecular structures of complexes 1 and 2 were investigated using X-ray diffraction of single crystal, Hirshfeld analysis, and density functional theory calculations. The Cl…H (11.7%) and O…H (24.7%) contacts are the most important in 1 , whereas the molecular packing of 2 is controlled mainly by the O…H (58.7%) hydrogen bonds. Complex 2 showed better activity against Escherichia coli, Bacillus subtilis, and Candida albicans compared with the standard antibiotics amoxicillin, tetracycline, and ampicillin. In general, complexes 1 and 2 showed good antimicrobial activity than these antibiotics and have the advantage to be used as both antibacterial and antifungal agents.     

Complexes of Mn(II), Co(II), Ni(II), Cu(II) and Zn(II) with 4-chloro-2-methoxybenzoic acid anion

The complexes of 4-chloro-2-methoxybenzoic acid anion with Mn²⁺, Co²⁺, Ni²⁺, Cu²⁺ and Zn²⁺ were obtained as polycrystalline solids with general formula M(C₈H₆ClO₃)₂·nH₂O and colours typical for M(II) ions (Mn – slightly pink, Co – pink, Ni – slightly green, Cu – turquoise and Zn – white). The results of elemental, thermal and spectral analyses suggest that compounds of Mn(II), Cu(II) and Zn(II) are tetrahydrates whereas those of Co(II) and Ni(II) are pentahydrates. The carboxylate groups in these complexes are monodentate. The hydrates of 4-chloro-2-methoxybenzoates of Mn(II), Co(II), Ni(II), Cu(II) and Zn(II) heated in air to 1273 K are dehydrated in one step in the range of 323–411 K and form anhydrous salts which next in the range of 433–1212 K are decomposed to the following oxides: Mn₃O₄, CoO, NiO and ZnO. The final products of decomposition of Cu(II) complex are CuO and Cu. The solubility value in water at 293 K for all complexes is in the order of 10^–3 mol dm^–3. The plots of χ_M vs. temperature of 4-chloro-2-methoxybenzoates of Mn(II), Co(II), Ni(II) and Cu(II) follow the Curie–Weiss law. The magnetic moment values of Mn²⁺, Co²⁺, Ni²⁺ and Cu²⁺ ions in these complexes were determined in the range of 76−303 K and they change from: 5.88–6.04 μ_B for Mn(C₈H₆ClO₃)₂·4H₂O, 3.96–4.75 μ_B for Co(C₈H₆ClO₃)₂·5H₂O, 2.32–3.02 μ_B for Ni(C₈H₆ClO₃)₂·5H₂O and 1.77–1.94 μ_B for Cu(C₈H₆ClO₃)₂·4H₂O.     

Three new binuclear copper(II) complexes with isonicotinic acid N-oxide: syntheses,crystal structures and properties

Three new copper(II) complexes with isonicotinic acid N-oxide (HL) and 1,10-phenanthroline (phen) as ligands, [Cu(L)(phen)(H₂O)]₂(NO₃)₂···2H₂O (1), [Cu(L)(phen)(H₂O)]₂(ClO₄)₂···2H₂O (2), and [Cu(L)(phen)Br]₂- [Cu(L)(phen)(H₂O)]₂Br₂···6H₂O (3) have been synthesized and structurally characterized. The structures of all three complexes feature a Cu₂ dimer formed by two Cu(II) ions interconnected by two bridging ligands. Each copper(II) ion has a distorted square pyramidal coordination geometry with elongated axial coordination by an aqua ligand or halogen anion. The isonicotinic acid N-oxide anion is bidentate, being coordinated to two Cu(II) ions through its N-O oxygen and one of its carboxylate oxygen atoms. Magnetic susceptibility measurements show a Curie–Weiss paramagnetic behavior characteristic of one unpaired electron for a copper(II) ion for all three complexes.     

Synthesis and electrochemical study of 2-(2-pyridyl)benzothiazole complexes with transition metals (CoII, NiII, and CuII). Molecular structure of aquabis[2-(2-pyridyl)benzothiazole]copper(II) diperchlorate

The reactions of 2-(2-pyridyl)benzothiazole (1) with MX₂·nH₂O salts (M = Ni^II, Co^II, or Cu^II; X = Cl or ClO₄; n = 0–2) in EtOH afforded the corresponding complexes. Depending on the nature of the counterion in the starting metal salt, the reactions give compounds of composition M(1)Cl₂·nH₂O or Cu(1)₂(ClO₄)₂·H₂O. The molecular and crystal structure of the Cu^II(1)₂(ClO₄)₂·H₂O complex was established by X-ray diffraction. The copper atom in this complex has a distorted tetragonal-pyramidal ligand environment and is coordinated by four nitrogen atoms of two ligand molecules and one water molecule. Electrochemical study of the ligand and the resulting complexes by cyclic voltammetry and at a rotating disk electrode demonstrated that ligand 1 stabilizes reduced forms of complexes containing Ni, Co, or Cu atoms in the oxidation state +1. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 1738–1744, October, 2006.     

Synthesis, crystal structures, and properties of inorganic-organic hybrid complexes constructed from copper(II) macrocyclic fragment

Reaction of a macrocyclic copper(II) complex [Cu(L)](ClO₄)₂ · 3H₂O (I) (L = 1,3,10,12,16,19-hexaazatetracyclotetracosane) with a hexapod carboxylate ligand H₆TTHA (H₆TTHA = 1,3,5-triazine-2,4,6-triamine hexaacetic acid) and a tripod carboxylate ligand H₃TATB (H₃TATB = 4,4′,4″-S-triazine-2,4,6-triyl-tribenzoic acid) yielded two mononuclear copper(II) complexes [Cu(L)][H₄TTHA] · 4H₂O (II) and [Cu(L)][HTATB] · 4H₂O (III). The complexes I–III have been structurally characterized. The crystal structures of complexes II and III show the copper(II) ion has a distorted pentacoordinate square-pyramidal geometry with two secondary and two tertiary amines from the macrocyclic complex [Cu(L)]²⁺ and one oxygen atom from the carboxylate ligand group at the axial position. The UV-Vis spectra are utilized to discuss the hydrolysis of the complex II.     

Synthesis,characterization and biological activity of triaminoxime and its metal complexes

Mn(II), Fe(III), Co(II), Ni(II), Cu(II) and Zn(II) complexes of multifunctional triaminoxime have been synthesized and characterized by elemental analyses, IR, UV–Vis spectra, magnetic moments, ¹H- and ¹³C-NMR spectra for ligand and its Ni(II) complex, mass spectra, molar conductances, thermal analyses (DTA, DTG and TG) and ESR measurements. The IR spectral data show that the ligand is bi-basic or tri-basic tetradentate towards the metals. Molar conductances in DMF indicate that the complexes are non-electrolytes. The ESR spectra of solid copper(II) complexes [(HL)(Cu)₂(Cl)₂] · 2H₂O (2) and [(L)(Cu)₃(OH)₃(H₂O)₆] · 7H₂O (6) show axial symmetry of a d _{x²???y ²} ground state; however, [(HL)(Co)] (4) shows an axial type with d _Z ² ground state and manganese(II) complex [(L)(Mn)₃(OH)₃(H₂O)6] · 4H₂O (10) shows an isotropic type. The biological activity of the ligand and its metal complexes are discussed.     

Synthesis,Characterization, X‐ray Structures,and Solution Studies of Nickel(II) Complexes of an Aza‐Crown Macrocycle with a Hydroxyl Pendant‐Armed

The 18‐membered mixed‐donor macrocycle 6,7,8,9,10,11,12,13,20,21‐decahydro‐5H, 19H‐dibenzo[b,m][1,15,5,8,11]dioxatriazacyclooctadecin‐20‐ol ( L ), which contains N₃O₃ donor set, was synthesized. Also two nickel(II) complexes of L have been synthesized and characterized by X‐ray crystallography, FT‐IR, UV‐Vis absorption spectroscopy and elemental analysis. The structure of complexes shows an unexpected anion dependence. Reaction of Ni(ClO₄)₂·6H₂O with L afforded [Ni L ](ClO₄)₂·CH₂Cl₂ complex in which L uses all donor atoms and acts as a hexadentate ligand so forming a mononuclear nickel(II) complex in distorted octahedral geometry. Contrasting with this, when NiCl₂·6H₂0 is used, the product complex [{Ni L Cl}₂(μ‐Cl)₂] is dimeric and consists of two Ni L Cl units bridged by two chloride ions. The coordination geometry of each nickel atom is a distorted octahedral. In this complex L is exo‐coordinated via only three nitrogen atoms to a nickel ion, which is bound to two cis bridging chloride and one non‐bridging chloride too. Also complexing properties of L towards Ni(ClO₄)₂·6H₂O and NiCl₂·6H₂0 have been determined by UV‐Vis titration in methanol. The computer treatment of the data confirmed the 1:1 metal to ligand stoichiometry for two complexes in solution and gave reliable values for corresponding stability constants (logK = 3.00 ± 0.02 with Ni(ClO₄)₂·6H₂O and logK = 3.29 ± 0.06 with NiCl₂·6H₂0).     

Synthesis and study of cobalt(II), nickel(II), and copper(II) complexes with 4-(4-hydroxyphenyl)-1,2,4-triazole

New complexes of Co(II), Ni(II), and Cu(II) nitrates, chlorides, and perchlorates with 4-(4-hydroxyphenyl)-1,2,4-triazole (L) were obtained and examined by single-crystal X-ray diffraction, X-ray powder diffraction, and electronic absorption and IR spectroscopy. The cations of all the complexes have linear trinuclear structures. Ligand L is coordinated to the metal ions in a bidentate bridging fashion through the N(1) and N(2) atoms of the heterocycle. The coordination polyhedron of the metal atoms is a distorted octahedron. The molecular and crystal structures of the complexes [Co₃L₆(H₂O)₆](ClO₄)₆ · 3C₂H₅OH · 3.75H₂O and [M₃L₆(H₂O)₆](ClO₄)₆ · 6H₂O (M = Cu²⁺ and Ni²⁺) were determined.     

Synthesis in solvent-free conditions,characterization and biological activity of a new Schiff-base ligand and its Cu(II) complex

A new bis-imine Schiff base (N₈O₂ donor, LH₂) has been synthesized by melt condensation of 3-amino-1,2,4-triazole with 1,5-bis(2′-formylphenyl)-1,5-dioksapentane in 2 : 1 molar ratio, in solvent and solvent-free conditions. The ligand has been characterized using FTIR, UV–Vis, ¹H NMR, ¹³C NMR, mass spectra, elemental analysis, and thermal (TGA-DSC) techniques. A new complex of LH₂ with Cu(II) has been synthesized in solvent and solvent-free conditions. FTIR, UV–Vis mass spectra, and thermal analysis (TGA-DSC) have been used to characterize the Cu(II) complex. Thermal degradation showed that the final products were black carbon and metallic copper. Distorted octahedral geometry has been observed around CuLH₂Cl₂ · LH₂ and its Cu(II) complex have been screened for in vitro antifungal and antioxidant activities. Antioxidation was determined for their superoxide scavenging and reducing activities. The ligand and its Cu(II) complex have strong antifungal activity against Aspergillus niger. The compounds have significant superoxide anion radical scavenging activity and reducing power against various antioxidant systems in vitro.     

Synthesis, structural characterization and electrochemical studies of new macrocyclic Schiff base containing pyridine head and its metal complexes

A new macrocyclic ligand, 1,3,5-triaza-2,4:7,8:13,14-tribenzo-9,12-dioksa-cyclopentadeca-1,5-diene was synthesized by reaction of 2,6-diaminopyridine and 1,2-bis(2-carboxyaldehyde phenoxy)ethane. Then, its Cu(II), Ni(II), Pb(II), Co(III) and La(III) complexes were synthesized by the template effect by the reaction of 2,6-diaminopyridine and 1,2-bis(2-carboxyaldehyde phenoxy)ethane and Cu(NO₃)₂ · 3H₂O, Ni(NO₃)₂ · 6H₂O, Pb(NO₃)₂, Co(NO₃)₂ · 6H₂O, La(NO₃)₃ · 6H₂O, respectively. The ligand and its metal complexes have been characterized by elemental analysis, IR, ¹H and ¹³C NMR, UV-Vis spectra, magnetic susceptibility, thermal gravimetric analysis, conductivity measurements, mass spectra, and cyclic voltammetry. All complexes are diamagnetic and Cu(II) complex is binuclear. The Co(II) was oxidized to Co(III). The comparative electrochemical studies show that the nickel complex exhibited a quasi-reversible one-electron reduction process, while copper and cobalt complexes gave irreversible reduction processes in DMSO solution.