Tetraaza Macrocyclic Schiff Base Research Articles

Novel tetraaza macrocyclic Schiff base complexes of bivalent zinc: microwave-assisted green synthesis, spectroscopic characterization, density functional theory calculations, molecular docking studies, in vitro antimicrobial and anticancer activities.

In the present manuscript, novel macrocyclic Schiff base complexes [Zn(N4MacL1)Cl2-Zn(N4MacL3)Cl2] were synthesized by the reaction of ZnCl2 and macrocyclic ligands (N4MacL1-N4MacL3) derived from diketone and diamines under microwave irradiation method and conventional method. The structures of the obtained complexes were identified by various spectrometric methods such as Fourier transformation infra-red (FT-IR), nuclear magnetic resonance (NMR), high-resolution mass spectrometry (HR-MS), powder X-ray diffraction, molar conductivity, and UV-vis. The structures of the synthesized compounds were optimized by using the def2-TZV/J and def2-SVP/J Coulomb fitting basis sets at B3LYP level in density functional theory (DFT) calculations. The macrocyclic Schiff base complexes exhibited higher activities against Gram-positive bacteria (Staphylococcus aureus and Bacillus cereus), Gram-negative bacteria (Escherichia coli and Xanthomonas campestris), and fungal strains (Fusarium oxysporum and Candida albicans) in comparison to macrocyclic Schiff base ligands. Furthermore, the newly synthesized macrocyclic compounds were assessed for their anticancer activity against three cell lines: A549 (human alveolar adenocarcinoma epithelial cell line), HT-29 (human colorectal adenocarcinoma cell line), and MCF-7 (human breast adenocarcinoma cell line) using the MTT assay. The obtained results showed that the macrocyclic complex [Zn(N4MacL3)Cl2] displayed the highest cytotoxic activity (2.23 ± 0.25µM, 6.53 ± 0.28µM, and 7.40 ± 0.45µM for A549, HT-29, and MCF-7 cancer cell lines, respectively). Additionally, molecular docking investigations were conducted to elucidate potential molecular interactions between the synthesized macrocyclic compounds and target proteins. The results revealed a consistent agreement between the docking calculations and the experimental data.

Pharmacologically important tetraaza macrocyclic Schiff base complexes of Zn(II), Cu(II) and Co(II): Synthesis, characterization, DFT studies, molecular docking and in vitro anti-bacterial and anti-cancer studies

A novel tetraaza macrocyclic Schiff base ligand and its metal complexes [Zn(II), Cu(II), and Co(II)] were successfully synthesized and characterized using various analytical techniques including FT-IR, NMR, ESI-MS, UV-Vis, PXRD, ESR, and TGA. The chemical reactivity and molecular geometry of the compounds were further elucidated through DFT calculations. The synthesized compounds were evaluated for their anti-bacterial activity against both Gram +ve and Gram -ve bacteria. Remarkably, the metal complexes exhibited enhanced anti-bacterial activity compared to the ligand. All compounds displayed moderate antibacterial activity against various strains, with complexes 4a and 4b demonstrating the highest inhibition against Gram +ve bacteria at 0.1 µM concentration. Furthermore, the cytotoxicity of these compounds against a human liver cancer cell line (HepG2) was assessed, revealing substantial anti-proliferative activity. Notably, the Zn(II) complex demonstrated an IC50 value comparable to the standard drug Doxorubicin. Importantly, the ligand and Zn(II) and Co(II) complexes exhibited minimal (< 5%) hemolysis at their IC50 values, suggesting their non-toxic nature. Molecular docking studies were conducted to investigate the binding interactions of the synthesized compounds with the active site of the topoisomerase IIβ enzyme (PDB ID: 4G0V), a crucial target for anti-bacterial and anti-cancer medications. Complex 4a displayed the strongest binding affinity (-8.2 kcal/mol) and the most favourable docked conformation, with multiple hydrogen bonds to the protein's active site. These results suggest its potential for further development as a therapeutic agent.

Synthesis, Thermogravimetric and Spectroscopic Characterizations of New Tetraazamacrocyclic Schiff Base Ligand and Some Metal Complexes

In the present study, metal complexes of Mn(II), Ni(II), Co(II), Cu(II) and Hg(II) were synthesized using new Tetraazamacrocyclic Schiff Base (5E,8E,14E,17E)-6,8,15,17-tetramethyl-1,2,3,4,4a,7,9a,10,11,12,13,13a,16,18a-tetradecahydrodibenzo [b,i][1,4,8,11]tetraazacyclotetradecine (L) derived from 1,2-diamino cyclo hexane with the acetyl acetone. Compounds have been exanimated and confirmed by fourier-transform infrared (FT-IR), ultraviolet-visible (UV-visible), proton nuclear magnetic resonance (1HNMR), carbon nuclear magnetic resonance (13CNMR), microelemental analyses (CHN), thermal analysis (TG), conductivity and magnetic susceptibility. The propose geometry for all complexes [MLCl2] structures were octahedral. Thermogravimetric of cobalt complex was carried out in two steps by fission into several small aggregates.

One-pot synthesis, characterization, photocatalytic activity and biological studies of Co(II), Ni(II) and Cu(II) complexes of a tetraazamacrocyclic Schiff base

Template condensation between pentane-1,5-dial and triethylenetetramine in the presence of divalent metal salts in methanolic solution resulted in mononuclear 15-membered tetraazamacrocyclic Schiff base metal complexes, [M(C11H22N4)X2], where M = Co(II), Ni(II) and Cu(II), X = Cl− and C11H22N4 is the tetradentate macrocyclic ligand. The bonding and overall geometry of the complexes are inferred through elemental analysis, FT-IR, UV–vis, 1H/13C NMR, ESI-mass, molar conductance, magnetic susceptibility and TG measurements. On the basis of the absorption bands in UV–vis spectra and magnetic moment analyses, a six-coordinate octahedral geometry is proposed for all the metal complexes. The formulation of the metal chelates is compatible with the thermal decomposition profiles. Photocatalytic efficiency of the macrocyclic Ni(II) complex was studied using solar water-splitting. The in vitro antimicrobial activity of metal complexes has been tested against certain bacterial and fungal species. The scavenging ability of DPPH free radicals was used to test the antioxidant activity of the complexes. In addition, MTT assay was used to assess the cytotoxicity of Cu(II) chloro complex against L929 mouse fibroblast cell lines.

Nanomagnetic tetraaza (N4 donor) macrocyclic Schiff base complex of copper(ii): synthesis, characterizations, and its catalytic application in Click reactions.

In this research, a novel nanomagnetic tetra-azamacrocyclic Schiff base complex of copper(ii) was produced via a post-synthetic surface modification of an Fe3O4 surface by a silane-coupling agent that contains acetylacetone functionalities at the end of its chain. Moreover, the target Cu complex that involves a tetradentate Schiff base ligand was obtained from a template reaction with o-phenylenediamine and Cu(NO3)2·3H2O. Furthermore, the prepared complex was nominated as [Fe3O4@TAM-Schiff-base-Cu(II)]. The Fourier-transform infrared (FT-IR) analysis indicates the presence of a Schiff-base-Cu complex in the catalyst. X-ray spectroscopy (EDS) and TGA analysis reveal that approximately 6-7% of the target catalyst comprises hydrocarbon moieties. The scanning electron microscope (SEM) and transmission electron microscopy (TEM) images demonstrate the presence of uniformly shaped particles, nearly spherical in nature, with sizes ranging from 9 to 18 nm. [Fe3O4@TAM-Schiff-base-Cu(II)] was applied as a catalyst for the click synthesis of a diverse range of 5-substituted-1H-tetrazoles in PEG-400 as a green medium. Regarding the electrical properties of the Cu(ii) complex, the presence of a tetra-aza (N4 donor) macrocyclic Schiff base as an N-rich ligand was reasonable - leading to its excellent capacity to catalyze these organic transformations. Finally, the high magnetization value (44.92 emu g-1) of [Fe3O4@TAM-Schiff-base-Cu(II)] enables its recycling at least four times without compromising the catalytic efficiency.

High incorporation of magnetite nanoparticles inside tetraaza macrocyclic Schiff base cavity: spectroscopic characterization and modeling by DFT calculation

This work presents a simple synthesis of tetraaza macrocyclic Schiff base ligand (C40H28N4), its complex [(C40H28N4)@Fe(II)], and a novel complex of magnetite Fe3O4NPs incorporated inside tetraaza macrocyclic cavity [(C40H28N4)@Fe3O4NPs] by the co-precipitation method in order to obtain well-dispersed nanoparticles, controlled size and prevent the aggregation of Fe3O4 NPs due to strong dipole–dipole magnetic attractions and interactions between particles. The characterization and structural identification were carried out by X-ray spectroscopy as well by 1H NMR, 13C and DEPT 135 NMR spectroscopy, FT-IR, UV–visible, EDX, TGA, and finally by VSM using both experimental and theoretical methods. XRD measurements indicate that the presence of Schiff's bases does not modify the crystal structure of the nanoparticles (11.05 nm). All the NMR spectra suggested the success of the synthesis of all structures with high purity. FTIR was used to illuminate the presence of Fe3O4NPs in tetrahedral and octahedral sites as well as their coordination with imine (C = N) of tetraaza macrocyclic. The UV–visible spectra and frontier molecular orbitals (FMOs) of the title compounds were calculated at TD-DFT/CAM-B3LYP-D3/6–311 G (d, p) level of theory. The corresponding calculated result yield shows a good agreement with the experimental data. The morphological characterization of the nanoparticles was carried out by SEM, which revealed that the shape of the NPs was generally spherical. The SEM images also show that the nanoparticles prepared by in situ with co-precipitation method were able to form stable complexes. Thermal characterization by TGA shows that there are 64% of the magnetite nanoparticles formed in situ, which corresponds to a grafting density of 25 mmol.g−1. The VSM analysis displays a similar magnetic hysteresis loop shape compared to free Fe3O4 NPs, which confirmed a ferromagnetic character due to the significant decrease in saturated magnetization.Graphical abstract

Functionalization of developed bacterial cellulose with magnetite nanoparticles for nanobiotechnology and nanomedicine applications

This paper deals with the preparation of novel magnetic materials made from tetraaza macrocyclic Schiff base bacterial cellulose ligands with magnetite nanoparticles (Fe3O4NPs) through a multi-step procedure for antimicrobial and cytotoxic activities and chemotherapy in cancer treatment. First, the 2,3-dialdehyde bacterial cellulose (DABC) was chemically modified by ethylenediamine (EDA) and benzil (Bzl) in the presence of ferrous ions. Then, the magnetite nanoparticles (Fe3O4NPs) was produced inside the complex [Fe(DABC-EDA-Bzl)Cl2] through a co-precipitation method. In nanobiotechnology, the magnetic [Fe3O4NP-INS-(DABC-EDA-Bzl)] material was showed moderate antimicrobial and cytotoxic activities against different species and cells, respectively. In particular, the magnetic [Fe3O4NP-INS-(DABC-EDA-Bzl)] material have not any cytotoxic activity towards peripheral blood mononucleocyte (PBMC) cells. Anti-tumor studies demonstrated that the magnetic [Fe3O4NP-INS-(DABC-EDA-Bzl)] material effectively inhibits the growth of the CT26 tumor model in BALB/c mice compared with other resulting materials throughout the experimental period and can be effective drug delivery in nanomedicine.

Cobalt(II) Pentaaza-Macrocyclic Schiff Base Complex as Catalyst for Light-Driven Hydrogen Evolution in Water: Electrochemical Generation and Theoretical Investigation of the One-Electron Reduced Species.

We previously reported that the tetraazamacrocyclic Schiff base complex [CoIII(CR14)(X)2]n+ (CR14 = 2,12-dimethyl-3,7,11,17-tetraazabicyclo[11.3.1]heptadeca-1(17),2,11,13,15-pentaene, X = Cl (n = 1) (1-Cl2) or H2O (n = 3) (1-(H2O)2)) is a very efficient H2-evolving catalyst (HEC) in fully aqueous solutions at pH 4.0-4.5 when used in a photocatalytic system including a photosensitizer and ascorbate as sacrificial electron donor. The excellent H2-evolving activity of this complex, compared to other cobalt and rhodium catalysts studied in the same photocatalytic conditions, can be related to the high stability of its two-electron reduced form, the putative "Co(I)" state. These very interesting results led us to investigate the H2-evolving performances of a series of compounds from a close-related family, the pentaaza-macrocyclic cobalt [CoII(CR15)(H2O)2]Cl2 complex (2, CR15 = 2,13-dimethyl-3,6,9,12,18-pentaazabicyclo[12.3.1]octadeca-1(18),2,12,14,16-pentaene), which comprises a larger macrocycle with five nitrogen atoms instead of four. Electrochemical as well as spectroscopic investigations in CH3CN coupled to density functional theory (DFT) calculations point to decoordination of one of the amine upon reduction of Co(II) to the low-valent "Co(I)" form. The resulting unchelated amine could potentially act as a proton relay promoting the H2 formation via proton-coupled-electron transfer (PCET) reactions. Besides, the iron, manganese, and zinc analogues, [FeII(CR15)(X)2]n+ (X = Cl (n = 0) or H2O (n = 2)) (3), [MnII(CR15)(CH3CN)2](PF6)2 (4), and {[ZnII(CR15)Cl](PF6)}n (5) were also synthesized and investigated. The photocatalytic activity of 2-5 toward proton reduction was then evaluated in a tricomponent system containing the [RuII(bpy)3]Cl2 photosensitizer and ascorbate, in fully aqueous solution. The photocatalytic activity of 2 was also compared with that of 1 in the same experimental conditions. It was found that the number of catalytic cycles versus catalyst for 2 are slightly lower than that for 1, suggesting that if the amine released upon reduction of 2 plays a role in promoting the H2-evolving catalytic activity, other factors balance this effect. Finally, photophysical and nanosecond transient absorption spectroscopies were used to investigate the photocatalytic system.

Synthesis and characterization of Ni (II), Cu (II), Fe (II) and Fe3O4 nanoparticle complexes with tetraaza macrocyclic Schiff base ligand for antimicrobial activity and cytotoxic activity against cancer and normal cells

This work describes a simple synthesis of complexes of the type [M(C32H28N4)Cl2], where M = Ni (II), Cu (II) and Fe (II) and a novel complex of magnetite nanoparticle (Fe3O4NP) inside (INS) tetraaza macrocyclic Schiff base ligand (C32H28N4): [Fe3O4NP‐INS‐(C32H28N4)], which was prepared by using a novel co‐precipitation method of coordinated ferric ion (Fe3+) in the complex [Fe(C32H28N4)Cl2] under mild conditions. The synthesized compounds were characterized and compared with a various physic‐chemical techniques like: Fourier transform infrared (FT‐IR), ultraviolet–visible spectroscopic techniques (UV–Vis), 1‐dimensional (1D) 1H‐NMR, 13C‐NMR spectroscopic techniques, mass spectra, Powder X‐ray diffraction (PXRD), Vibrating sample magnetometer (VSM), Scanning electron microscopy (SEM), elemental analysis and molar conductance measurements. Furthermore, the highest saturation magnetization was 26.56 emu.g−1 obtained from [Fe3O4NP‐INS‐(C32H28N4)] (diameter of Fe3O4NPs~20.87 nm) that prove easy separation by an external magnetic field. In vitro screening of all the compounds against different species of bacteria and fungi shows that [Fe3O4NP‐INS‐(C32H28N4)] is effective against the tested strains as compared to the tetraaza macrocyclic ligand and selected complexes. The cytotoxic activity of the all compounds was also examined in 3 human tumor cell lines as U87, MDA‐MB‐231 and LS‐174. The complex [Fe3O4NP‐INS‐(C32H28N4)] shows moderate and strong cytotoxic activity against brain cancer, colon cancer and breast cancer (U87, MDA‐MB‐231 and LS‐174 respectively), without showing cytotoxicity towards peripheral blood mononucleocyte (PBMC) cells.

Sono-heterogeneous Fenton system for degradation of AB74 dye over a new tetraaza macrocyclic Schiff base cellulose ligand-loaded Fe3O4 nanoparticles

The study detailed herein is related to the synthesis of novel tetraaza macrocyclic Schiff base cellulose ligand: (EDA-g-DAC) via condensation reaction of periodate oxidized developed microcrystalline cellulose (DAC) with ethylenediamine (EDA) was reported. Additionally, tetraaza macrocyclic Schiff base cellulose ligand-loaded Fe3O4 nanoparticles: [(EDA-g-DAC)@Fe3O4] was successfully prepared using in situ chemical co-precipitation of coordinated ferric and ferrous ions in the tetraaza macrocyclic Schiff base cellulose ligand: (EDA-g-DAC) under mild conditions. The synthesized compounds were investigated by X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, scanning electron microscope (SEM), thermogravimetric analysis (TGA) and vibrating sample magnetometer (VSM). [(EDA-g-DAC)@Fe3O4] was of a narrow size distribution, and exhibited ferromagnetic behaviors with saturation magnetization 24.63 emu g−1. The degradation of Indigo Carmine (AB74) over [(EDA-g-DAC)@Fe3O4] was studied using a coupled ultrasound/heterogeneous or sono-heterogeneous Fenton process. More importantly, US + [(EDA-g-DAC)@Fe3O4] + H2O2 were demonstrated for the first time as a high efficient for the degradation of AB74. The pseudo first-order-reaction constant of US + [(EDA-g-DAC)@Fe3O4] + H2O2 were measured to be 0.0979 min−1. Total Organic Carbon (TOC) and Chemical oxygen demand (COD) removal rates are 0% and 98.7%, respectively. Additionally, the [(EDA-g-DAC)@Fe3O4] showed the higher enhanced sonocatalytic degradation of AB74 than other dyes MB and AY17. Furthermore, the catalysts can be easily recycled within 10 s using an external magnetic field and a constant catalytic activity is retained even after five cycles.

Synthesis, spectroscopic characterization, DNA interaction and antibacterial study of metal complexes of tetraazamacrocyclic Schiff base

The template condensation reaction between benzil and 3,4-diaminotoulene resulted mononuclear 12-membered tetraimine macrocyclic complexes of the type, [MLCl2] [M=Co(II), Ni(II), Cu(II) and Zn(II)]. The synthesized complexes have been characterized on the basis of the results of elemental analysis, molar conductance, magnetic susceptibility measurements and spectroscopic studies viz. FT-IR, 1H and 13C NMR, FAB mass, UV–vis and EPR. An octahedral geometry has been envisaged for all these complexes, while a distorted octahedral geometry has been noticed for Cu(II) complex. Low conductivity data of all these complexes suggest their non-ionic nature. The interactive studies of these complexes with calf thymus DNA showed that the complexes are avid binders of calf thymus DNA. The in vitro antibacterial studies of these complexes screened against pathogenic bacteria proved them as growth inhibiting agents.

Synthesis, Spectroscopic Characterization, and In Vitro Antimicrobial Screening of 16-Membered Tetraazamacrocyclic Schiff-Base Ligand and its Complexes with Co(II), Ni(II), Cu(II), and Zn(II) Ions

A 16-membered tetraazamacrocyclic ligand has been synthesized by condensation reaction of 2-methyl acetoacetanilide with 1,8-diaminonaphthalene, and the metal complexes of the type [MLCl2] [M = Co(II), Ni(II), Cu(II), Zn(II)] were prepared by interaction of the ligand with metal salts. The ligand and its complexes were characterized by various spectroscopic studies. The mode of bonding and the overall geometry of these complexes have been deduced by elemental analysis, molar conductance values, Fourier-transform infrared (FT-IR), 1H-nuclear magnetic resonance (NMR), fast-atom bombardment (FAB) mass, electron paramagnetic resonance (EPR), and ultraviolet–visible (UV-VIS) spectroscopy along with magnetic measurement studies. An octahedral geometry has been envisaged for all these complexes, while a distorted octahedral geometry has been noticed for the Cu(II) complex. The cyclic voltammograme of the Cu(II) complex exhibits a quasi-reversible one-electron transfer wave for the Cu(II)/Cu(I) couple. The low conductivity data of all the complexes suggest their nonionic nature. These complexes have also been screened against pathogenic bacteria and fungi in vitro as growth-inhibiting agents.

ChemInform Abstract: New Hexaaza Macrocyclic Binucleating Ligands. Oxygen Insertion with a Dicopper(I) Schiff Base Macrocyclic Complex.

Direct 2:2 condensation of isophthalaldehyde with diethylenetriamine produces a hexaaza 24-membered macrocyclic tetra Schiff base in good yield. The crystal structure of an isomeric form of the Schiff base is reported. The amber binuclear Cu(I) complex of the tetraaza macrocyclic Schiff base combines with a molar equivalent of dioxygen to form a green binuclear Cu(II) complex, wich contains a bridging hydroxide ion and, by oxygen insertion, a bridging phenolate donor

Synthesis and Spectral Characterization of 14- and 16-membered tetraazamacrocyclic Schiff base ligands and their transition metal complexes and a comparative study of interaction of calf thymus DNA with copper(II) complexes

14 and 16 membered Schiff base macrocyclic ligands, 7,14-dimethyl-5,12-di(N-amino)-2-methylphenyl-1,4,8,11-tetraaza-cyclotetradecane-4,7,11,14-tetraene (L 1) and 8,16-dimethyl-6,14-di(N-amino)-2-methylphenyl-1,5,9,13-tetraaza-cyclohexadecane-5,8,13,16-tetraene (L 2) were synthesized by condensation reaction between 2′-methyleacetoacetanilide and aliphatic diamines. The metal complexes of the types, [ML 1](NO 3) 2 and [ML 2(NO 3) 2] [M = Co(II), Ni(II), Cu(II) and Zn(II)] were prepared by interaction of ligands, L 1 or L 2 with hydrated metal(II) nitrates. The ligands and their complexes were characterized by elemental analysis, IR, 1H and 13C NMR, EPR, UV–Vis spectroscopy, magnetic susceptibility, conductivity measurements and ESI-mass spectral studies. The results of elemental analyses, ESI-mass and conductivity measurements confirmed the stoichiometry of ligands and their complexes while the characteristic absorption bands and resonance peaks in IR and NMR spectra confirmed the formation of ligand frameworks around the metal ions. The square planar geometry for complexes derived from ligand L 1 and octahedral environment for complexes derived from ligand L 2 with distortion in Cu(II) complex have been confirmed on the basis of results of electronic and electron spin resonance spectral studies and magnetic moment measurements. Absorption and fluorescence spectral studies revealed different binding mode for complex, [CuL 1](NO 3) 2 as compared with [CuL 2(NO 3) 2] on interaction with calf thymus DNA.

Synthesis, Structural Characterization, Redox, and Antibacterial Studies of 12‐Membered Tetraaza Macrocyclic Cu(II), Ni(II), Co(II), Zn(II), and VO(IV) Complexes Derived from 1,2‐(Diimino‐4′‐antipyrinyl)‐1,2‐diphenylethane and o‐Phenylenediamine

A tetraaza macrocyclic Schiff base (L), synthesized from 1,2‐(diimino‐4′‐antipyrinyl)‐1,2‐diphenylethane and o‐phenylenediamine, acts as a tetradentate ligand and forms solid cationic complexes with Cu(II), Ni(II), Co(II) and VO(IV) salts in ethanol. All the synthesized compounds were characterized by microanalytical data, magnetic susceptibility measurements, IR, UV‐Vis., 1H NMR, 13C NMR, ESR and mass spectral techniques. The IR and UV‐Vis. spectral data and magnetic susceptibilities of the complexes suggest that the [CuL]Cl2, [NiL]Cl2, [CoL]Cl2 and [ZnL]Cl2 complexes exhibit square‐planar geometry whereas the [CuL(Y)2]Cl2 complexes show octahedral geometry, where Y = pyridine (py), imidazole (im) or triphenylphosphine (PPh3). The [VOL]SO4 complex has a square‐pyramidal geometry. The electrolytic behaviour of the chelates was assessed from their molar conductance data. The monomeric nature of the chelates was confirmed from their magnetic susceptibility values. Cyclic voltammogram of the [CuL]Cl2 complex in MeCN reveals that the unusual oxidation states such as Cu(III), Cu(I) and Cu(0) are stabilized by the ligand systems. The [CuL(py)2]Cl2 and [CuL(im)2]Cl2 complexes strongly enhance the copper(0) → copper(II) oxidation while the [CuL(PPh3)2]Cl2 complex completely suppresses the Cu(II)/Cu(III) couple and copper(0) → copper(II) oxidation. The cyclic voltammogram of the Ni(II), Co(II) and VO(IV) complexes were also recorded in MeCN solution and their salient features are reported. The ESR spectra of the copper and vanadyl complexes in DMSO solution at 300 and 77 K were recorded and their M.O. coefficients were calculated. The investigated compounds and uncomplexed metal salts were tested against bacteria like Staphylococcus aureus, Bacillus subtilis, Klebsiella pneumoniae, Salmonella typhi, Pseudomonas aeruginosa and Shigella flexneri. The metal salts have higher activity than the free ligand and the metal chelates.

A new tyrosinase model system: formation of a phenoxy- and hydroxy-bridged copper(II) complex with partial hydrolysis of a tetraaza macrocyclic Schiff base ligand

A new tetraaza macrocyclic ligand capable of providing two nitrogen coordination to each copper center has been utilized to model tyrosinase-like activity. Aromatic hydroxylation in one of the rings has been observed with concomitant partial hydrolysis of the macrocycle. The final dicopper(II) complex has a μ-phenoxo μ-hydroxo bridged structure as evidenced from spectroscopic and variable-temperature magnetic studies.

Synthesis of Copper(II) Selective Chelating Resin Bearing a Tetraaza Macrocyclic Schiff Base Ligand

Abstract The chelating resin bearing a tetraaza macrocyclic Schiff base ligand as a pendant group has been synthesized and found to have a high selectivity for copper(II) over nickel(II). This resin can be applied to a useful adsorbent for efficient separation of these metal ions in a column system.

Preparation of novel polymer ligands containing tetraaza macrocyclic schiff base as a highly selective extractant for copper(II)

Three types of the novel polymer ligands in which 6,8,15,17-tetramethyl-dibenzo-5,9,14,18-tetraaza-cyclotetradecene (L) is present as an integral part of the polymer backbone have been prepared. These polymer ligands are oligomers whose polymerization degree may be about five. Their complexing abilities and extractabilities for copper(II) and nickel(II) have been investigated. Among the polymer ligands, Poly-L3, which contains triethyleneglycol bis( p-phenylene) group as a linkage group, was found to be an excellent extractant for copper(II).

Preparation and characterization of a novel macrocyclic ligand—dinitro-tetraazacyclotetradeca-tetraene—and application as a highly selective extractant for copper(II)

A novel tetraaza macrocyclic Schiff base ligand, 6,13-dinitro-5,7,12,14-tetramethyl-1,4,8,11-tetraazacyclotetradeca-1,5,7,-12-tetraene, was prepared and its copper(II) and nickel(II) complexes were characterized. This ligand was found to be an excellent extractant for copper(II).