Spectral and thermal studies of new Co(II) and Ni(II) hexaaza and octaaza macrocyclic complexes

The macrocyclic complexes of Co(II) and Ni(II) having chloride or thiocyanate ions in the axial position have been synthesized and characterized. These complexes are synthesised by the template condensation of o-phenylenediamine or 2,3-butanedionedihydrazone with the appropriate aldehydes in NH₄OH solution in the presence of the metal ions, Co(II) and Ni(II). The complexes were characterized by spectroscopic methods (IR, UV-Vis and ESR) and magnetic measurements as well as thermal analysis (TG and DTA). The results obtained are commensurate with the proposed formulae. Spectral studies indicate that these complexes have an octahedral structure. From conductivity measurements the complexes are non-electrolytes. The kinetic of the thermal decomposition of the complexes was studied and the thermodynamic parameters are reported.     

A spectroscopic and electrochemical study of some copper(II) tetraaza macrocyclic complexes

Infrared, electronic, electron spin resonance and d.c. polarographic data for some copper(II) tetraaza macrocyclic complexes, involving a novel cyclam type ligand, are reported and are interpreted in terms of the structure of the complexes and the influence ofJahn-Teller distortion effects and cation-anion interactions.

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Eine spektroskopische und elektrochemische Untersuchung einiger makrocyclischer Kupfer (II)-Komplexe

Zusammenfassung Es wird über Infrarot-, Elektronenanregungs-, Elektronenspinresonanz- und D.C. Polarographie-Daten einiger tetraaza-makrocyclischer Kupfer(II)-Komplexe einschließlich eines neuen Cyclam-Typs als Ligand berichtet. Die Befunde werden hinsichtlich der Strukturen der Komplexe, dem Einfluß vonJahn-Teller-Verdrillungseffekten und Kation-Anion-Wechselwirkungen interpretiert.

     

Synthesis and characterization of chiral tetraaza macrocyclic nickel(II) and palladium(II) complexes

Chiral tetraaza macrocyclic nickel(II) and palladium(II) complexes 2a-e, containing one or two (R,R)-(-)-1,2-cyclohexanediyl bridges, were synthesized by template condensation reactions and characterized by (1)H and (13)C NMR, IR, UV-vis, and mass spectrometry. The electrophilic reactivity of 2a was explored. Crystal structures of Ni complex 2b and metal-free ligand 5 were determined by single-crystal X-ray diffraction.     

大环金属铜(II)、镍(II)配合物的模板合成与晶体结构

用模板法合成了1个大环金属铜(II)配合物[CuLCl₂]·3H₂O (1)和3个大环金属镍(II)配合物[NiLCl₂] (2)，[NiL](ClO₄)₂ (3)和[NiLH₂](ClO₄)₄ (4)(L=3,10-二乙基-1，3，5，8，10，12-六氮杂十四烷)，通过X-射线衍射单晶结构分析测定了它们的晶体结构。晶体结构显示：配合物1和2的金属离子与大环配体的4个氮原子及大环平面轴向的2个氯离子以八面体配位方式配位；配合物3和4的金属离子与大环配体的4个氮原子以平面正方形配位方式配位，配合物4的侧链氮原子的质子化导致侧链结构翻转，使得其侧链与大环平面共面。     

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.     

Synthesis,spectral and thermal properties of macrocyclic zinc(II) complexes

The new zinc ternary complexes [Zn(cyclen)NO₃]ClO4 (I), [Zn₂(cyclen)₂(m-nic)](ClO₄)₃ (II), [Zn₂(cyclen)₂(m-pic)](ClO₄)₃ (III) (cyclen=1,4,7,10-tetraazacyclododecane; nic=nicotinic acid; pic=picolinic acid) were synthesized and their spectral and thermal properties were investigated. The compounds were characterized by elemental analysis, IR spectroscopy and TG/DTG, DTA methods. Moreover, the way of coordination of pyridinecarboxylate anions was proposed on the basis of the spectral data and consequently proved with results of X-ray structure analysis. This revised version was published online in August 2006 with corrections to the Cover Date.     

Template-engineered metal macrocyclic complexes: Synthesis and biological activity

Three new azamacrocylic complexes of divalent transition-metal ions were synthesized by taking Co(II), Ni(II), and Cu(II) metal ions as templates. The macrocyclic ligand (1²Z,5²Z,5⁴E)-1¹,1²,1³,1⁴,1⁵,1⁶,5¹,5²,5³,5⁴,5⁵,5⁶-dodecahydro-2,4,6,8-tetraaza-1 (2,4),5(4,2)-pyrimidine-3,7(1,2)-dibenzenacyclooctaphane-1⁶,5⁶-dione was derived from o-phenylenediamine (OPD) and 2-thiobarbituric acid (TBA). All the complexes were fully characterized through spectroscopic techniques and elemental analyses. The structures of the macrocyclic complexes were determined by IR, UV–vis, ESI-MS, TGA, molar conductance, magnetic moment, and electron spin resonance data. On the basis of the above studies, the complexes may be formulated as [MLX₂], in which L is a macrocyclic ligand and X = CH₃COO⁻. All the macrocyclic complexes were biologically screened to evaluate their antimicrobial efficacy. DNA binding study of two representative complexes was performed by UV–vis titrations.     

Syntheses and spectroscopic studies on tetraaza macrocyclic complexes of praseodymium(III)

Praseodymium(III) macrocyclic complexes of types [Pr(L)(H₂O)₂]Cl₃, [Pr(mac₁)]Cl₃ and [Pr(mac₂)(H₂O)₂]Cl₃ (L = ligands derived by the condensation of diacetyl or benzil with semicarbazide or thiosemicarbazide; mac₁ = macrocyclic ligands derived by the condensation of diacetyl or benzil with carbohydrazide; mac₂ = macrocyclic ligands derived by the condensation of diacetyl or benzil with semicarbazide, thiosemicarbazide or thiocarbohydrazide) have been prepared and characterized by conductance magnetic moment, spectral data, thermal and elemental analyses.     

Synthesis and polarographic studies of some phenylazo substituted tetra-aza macrocycle complexes

The preparation of some phenylazo substituted tetra-aza macrocycle complexes is reported. The electrochemical properties of these compounds have been examined using polarographic and voltammetric techniques. These studies revealed that both the ligand and metal are electrochemically active. The reduction of the azo function has been shown to occur through a single four-electron process. When a nitro group was also present the nitro function was reduced in a six-electron wave, cathodic of the azo moiety.     

Co(II), Ni(II) and Cu(II) complexes of new [1+1] and [2+2] macrocyclic ligands derived from 1,4-bis(2′-formylphenyl)-1,4-dioxabutane and cis-1,2-diaminocyclohexane

Two new macrocyclic ligands, L¹ (14-membered N₂O₂) and L² (28-membered N₄O₄) from [1+1] and [2+2] condensation, respectively, have been obtained in a one-pot synthesis starting from 1,4-bis(2′-formylphenyl)-1,4-dioxabutane and cis-1,2-diaminocyclohexane.     

The crystal structures and electrochemical studies of two naphthalenic Schiff base copper(II) complexes

The Schiff base ligands, 2-hydroxy-N-cyclohexyl-l-naphthaldimine (I), and 3-hydroxy-N-cyclohexyl-2-naphthaldimine (II), and their corresponding Cu^II complexes (1–2) respectively were synthesized and characterized. The crystal and molecular structures of bis-{(cyclohexyl)[(2-oxo-1H-naphth-1-ylidene)-methyl]aminato}copper(II) (1) and bis-{(cyclohexyl)[(3-oxo-2H-naphth-2-ylidene)-methyl]aminato} copper(II) (2), were determined. The X-ray diffraction study shows that the geometry around the metal atom for (1), is stepped square planar with a step of 1.063 Å while for (2), the geometry around the metal atom for square planar with an angle between the coordination planes O(1)---Cu---N(1) and O(1a)---Cu---N(1a) of 39.9°. Electrochemical studies show a dependence of the Cu^II/Cu^I potentials on the ligand structure.     

Oxidation of tetraaza macrocyclic complexes of nickel(II) with peroxobisulfate ions

Spectrophotometry has been used to study the kinetics of oxidation of some tetraaza macrocyclic complexes of nickel (II) with peroxobisulfate ions in perchloric and sulfuric acid solutions. A scheme of the processes taking place has been proposed and the activation parameters of the reactions determined. The influence of different factors (pH value, ionic strength of the solution, temperature) on the kinetic parameters of the oxidation reactions has been studied. A significant influence of the conformations of the macrocyclic ligands in the complexes on the rate of the processes has been noticed.Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 24, No. 5, pp. 577–583, September–October, 1988.     

Synthesis and spectral studies of nickel(II) complexes derived from disalicylaldehyde oxaloyldihydrazone

The mononuclear nickel(II) complex [Ni(H₂slox)(H₂O)₃] (1) and polymeric dinuclear complexes [Ni₂(slox)(A₄)] {A = H₂O (2), py (3), 2-pic (4), 3-pic (5) and 4-pic (6)} and the discrete binuclear complexes [Ni₂(slox)(NN)₃] {NN = bpy (7) and phen (8)} have been synthesized from disalicylaldehyde oxaloyldihydrazone (H₄slox) in methanol. All of the complexes are nonelectrolytes. Complexes 1, 7, and 8 are paramagnetic while binuclear 2–6 possess anomalously low μ _eff value, indicating considerable metal–metal interaction. Discrete binuclear 7 and 8 have no interaction between the two nickel(II) ions. The anomalously low magnetic moment values in 2–6 are explained as metal–metal interaction via phenoxide bridge. Such metal–metal interactions are less in 7 and 8 due to coordination of bipyridine and phenanthroline molecules which do not allow phenoxide bridging. The dihydrazone coordinates to the metal center as a dibasic tridentate ligand in keto-enol form in staggered configuration in 1, while in the remaining complexes the dihydrazone is tetrabasic hexadentate in enol form in anticis configuration. The metal center has a tetragonally distorted octahedral stereochemistry.     

Mono and trinuclear lanthanide complexes of 13-membered tetraaza macrocycle: Synthesis and characterization

The reaction of 1,8-diamino-3,6-diazaoctane and diethyl malonate in dry methanol yielded a 13-membered macrocycle. Complexes of the type [Ln(tatd)Cl₂ (H₂O)₃]Cl [Ln^III=La, Pr, Nd, Sm, Eu, Gd, Tb, Dy; tatd=1, 5, 8, 11-tetra-azacyclotridecane-2,4-dione] have been synthesized by template condensation. The complex [La(tatd)Cl₂ (H₂O)₃]Cl in methanol was reacted with lanthanide chlorides to yield the trinuclear complexes of type [2{La(tatd)Cl₂(H₂O)₃}LnCl₃]Cl₂ [Ln^III=La, Pr, Nd, Sm, Eu, Gd, Tb, Dy]. The chemical compositions of mono and trinuclear complexes have been established on the basis of analytical, molar conductance, electrospray (ES) and fast atom bombardment (FAB) mass data. In mononuclear complexes the Ln³⁺ ion is encapsulated by four ring nitrogens and in trimetallic complexes the exo-carbonyl oxygens of two mononuclear units coordinate to the Ln³⁺ ions resulting in a polyhedron around the lanthanide ions. Thus the macrocycle is bonded in a tetradentate fashion in the former complexes and hexadentate in the latter. The coordination number nine around the encapsulated Ln³⁺ and seven around the exo-oxygen bonded Ln³⁺ ions are established. The symmetry of the ligand field around the metal ions is indicated from the emission spectra.     

Antimicrobial and DNA Cleavage Studies of New N2O2 Diazadioxa Macrocyclic Schiff Base Co(II), Ni(II) and Cu(II) Complexes Containing Triazole Head Unit: Synthesis and Spectroscopic Approach

A novel series of N₂O₂ diazadioxa macrocyclic complexes [MLCl₂] (M=Co²⁺, Ni²⁺ and Cu²⁺) have been synthesized with newly derived biologically active ligands (L^I-L^IV). These ligands were synthesized by the condensation of 1, 6-bis(2-formylphenyl)hexane and 3-subtituted-4-amino-5-hydrazino-1, 2, 4-triazole. The mode of bonding and overall geometry of the complexes have been inferred through IR, EPR, electronic spectral studies, conductivity, magnetic, thermal and electrochemical studies. All the complexes are soluble in DMF and DMSO and are non-electrolytes. All these complexes have been screened for their antibacterial (Escherichia coli, Staphylococus aureus, Salmonella typhi, Pseudomonas aeruginosa) and antifungal activities (Aspergillus niger, Aspergillus flavus and Cladosporium) by the MIC method. The DNA cleavage study was done by Agarose gel electrophoresis.     

An x-ray photoelectron spectroscopic study of some nickel(II) tetraaza macrocyclic complexes

Summary X-ray photoelectron spectra (XPS) of the Ni(2 p_{3/2, 1/2}), N(1s) and Cl(2p) core levels for seven nickel(II) tetraaza macrocyclic complexes and three related macrocycles of the basic cyclam and corrin ring structures are reported. Relative satellite intensities for the Ni(2p_3/2) level are also reported, where observed. The binding energy data for the core levels are interpreted in terms of structural features of these complexes, such as: (i) the conformation of the macrocyclic ring and the concomitant isomerism possibilities, (ii) the existence of “cluster-ions”, formed as a consequence of hydrogen bonding between macrocyclic cation and counter-ion, and (iii) the coordination number of nickel in these complexes. Additional information of chemical significance, which is derived from the binding energy data, concerns the magnetic properties of the complexes and an estimate of the degree of metal-ligand covalency.     

Carboxyester hydrolysis promoted by novel nano‐sized macrocyclic Zn(II) complexes

A novel series of nano‐sized Zn(II) macrocyclic complexes has been synthesized using the template method, i.e. by the in situ reaction of Schiff bases (derived from 1,4‐bis(4‐amino‐5‐mercapto‐1,2,4‐triazol‐3‐yl)alkanes/phenylene with salicylaldehyde/2‐hydroxyacetophenone) and 1,4‐dibromobutane in the presence of zinc(II) acetate dihydrate in ethanol. The complexes have been characterized using elemental analysis, infrared and NMR spectroscopies, scanning electron microscopy and thermal analysis. The catalytic properties of these complexes have been investigated kinetically for the hydrolysis of p‐nitrophenylacetate (PNPA) at 25°C in aqueous dimethylsulfoxide using phosphate buffer (pH = 7.0–8.5). During the reaction, absorbance of p‐nitrophenolate increases linearly with time (i.e. increase of p‐nitrophenolate concentration) which indicates that the rate of the reaction increases linearly with time. On the basis of these results, a plausible mechanism for the hydrolysis of PNPA is proposed. It is shown that coordinated water may serve as a good nucleophile that effectively catalyses PNPA hydrolysis. Therefore, these complexes may serve as model compounds for hydrolytic enzymes. Copyright © 2014 John Wiley & Sons, Ltd.