Spectral studies, cyclic voltammetry and synthesis of cobalt(II) and ruthenium(III) complexes with symmetric and asymmetric ring containing membered N2S2, N4, and N5 donor macrocyclic ligands

Reaction of divalent cobalt(II) and trivalent ruthenium(III) salts (NO3, SCN and SO4) with macrocyclic ligands L1, L2 and L3 having N2S2, N4 and N5 core, have been designed and carry out. All these three macrocyclic ligands and their complexes were obtained in pure form. Their structures were investigated by using microanalytical analyses, IR, mass, magnetic moments, electronic and EPR spectral studies. The redox properties of the complexes were also examined by cyclic voltammetry. An interesting feature of complexes is that the relatively large rings of macrocyclic ligands prevent the macrocyclic rings from approaching the metal center as closely as they would, if they were not constrained. So the Ru-N distances are longer than expected due to ring size. Electrochemical studies show that the macrocyclic ligand L1 is more effective electron donors to ruthenium than of L2 and L3. Electronic spectral properties also show that the sulphur donor atom of L1 weakens the ligand field with respect to ligand-to-metal charge-transfer band. However it is expected that second-row transition metal-ligand bonds tend to be weaker than third-row transition metal-ligand bonds. There are well-established examples of reactions in which decreased of reactivity down a triad of transition metals is not observed. These novelties are usually attributed to pi-bonding effects for ligands such as carbon monoxide, solvent effects, or a change in mechanism.     

Synthesis and spectral studies on mononuclear complexes of chromium(III) and manganese(II) with 12-membered tetradentate N2O2, N2S2 and N4 donor macrocyclic ligands

Complexes of Cr^III and Mn^II of general formula [Cr(L)X₂] X and [Mn(L)X₂] respectively were prepared from N₂O₂, N₂S₂ and N₄ donor macrocyclic ligands. The complexes have been characterized by elemental analysis, molar conductance measurements, spectral methods (i.r, mass, ¹H-n.m.r, electronic spectra and e.p.r.) and magnetic measurements. The macrocyclic ligands have three different donating atom cavities, one with two unsaturated nitrogens and the other two have saturated nitrogen, oxygen and sulphur atoms. The effect of different donor atoms on the spectra and ligand field parameters is discussed. All the complexes show magnetic moments corresponding to a high-spin configuration. On the basis of spectral studies a six coordinated octahedral geometry may be assigned to these complexes.     

两亲性大环多胺La(III)配合物的合成、表征及催化质粒DNA水解的研究

近年来,人工核酸切割试剂的研究一直是化学生物学、生物化学和分子生物学中最为活跃的前沿领域之一。最近的研究结果表明大环多胺金属配合物在磷酸二酯水解方面表现出独特的催化性能,能作为化学核酸酶有效的催化DNA和RNA的磷酸二酯键的水解[1-2]。尤其是电荷较高的金属阳离子形     

Metal ion recognition via 'selective detuning'. The interaction of selected transition and post-transition metal ions with a mono-N-benzylated O2N3-donor macrocycle and its xylyl-bridged ring analogue

The interaction of cobalt(II), nickel(II), copper(II), zinc(II), cadmium(II), silver(I) and lead(II) with symmetrical mono-N-benzylated and xylyl-linked macrocyclic ligands derived from the O2N3-macrocycle, 1,12,15-triaza-3,4:9,10-dibenzo-5,8-dioxacycloheptadecane, has been investigated. The log K values for the respective 1 : 1 complexes in 95% methanol (I= 0.1; Et4NClO4, 25 degrees C) of the mono-benzylated derivative have been determined potentiometrically and the results compared with the values obtained previously for the parent (non-benzylated) ring system as well as for related di- and tri-benzylated macrocyclic species. Mono-benzylation results in slightly enhanced stability for the 1 : 1 silver(I) complex while the values for the corresponding complexes of the other six ions are in each case decreased even though the highest stability is still maintained for the 1 : 1 copper(II) complex. The log K results are in accord with a previous proposal that N-benzylation of amine-containing macrocyclic rings of the present type will normally have only a minor (positive or negative) influence on the affinity towards silver(I) while the corresponding binding strengths towards the remaining six metal ions are significantly reduced-behaviour we term 'selective detuning'. Competitive seven-metal transport experiments across a bulk chloroform membrane have been performed using both ligand systems as ionophores. In parallel to the log K results, transport selectivity for copper(II) was exhibited by both systems, with similar transport efficiencies being evident when compared on a 'per macrocyclic cavity' basis.     

Complexes of N, S donor ligands. CoII, CoIII, MnIII, FeIII and PdII complexes of 1, 2-di( o -aminophenylthio)ethane: Synthesis, characterisation and reactions

The ligand 1,2-di(o-aminophenylthio)ethane (abbreviated as H₂DAPTE) has been allowed to react with various metal salts and the complexes isolated and characterised. In these complexes, H₂ DAPTE behaves as a neutral quadridentate and also as a dibasic quadridentate ligand after losing two protons from the amine functions. Two complexes of this ligand, reported earlier, have been condensed with acetone to form macrocyclic complexes of TDDH where TDDH is 13, 13, 15-trimethy1-2,5-dithia-12, 16-diazatricyclo-[15,3,0,0,6,11]-docosa-1(17), 6(11), 7,9,15,18,20-heptene.     

Divalent nickel,cobalt and copper complexes of a tetradentate N6 macrocyclic ligand

Summary Divalent nickel, cobalt and copper salts react with 2,6-diaminopyridine and acetylacetone to form complexes containing a 16-membered N₆ tetradentate macrocyclic ligand. The complexes are characterised as distorted octahedra of the M(TML)X₂ type where M=nickel(II), cobalt(II) and copper(II); TML=tetradentate macrocyclic ligand and X=Cl, Br, NO₃ or NCS. The ligand coordinates through all the four azomethine nitrogen atoms which are bridged by acetylacetone moieties. Pyridine nitrogen does not participate in coordination, a fact supported by far i.r. studies. The magnetic, electronic and i.r. spectral studies indicate that the complexes have lower symmetries and the amounts of distortion calculated in terms of DT/DQ applying normalised spherical harmonic Hamiltonian theory indicate that these complexes are moderately distored.     

Iron compounds in controlled radical polymerization: Ferrocenes, (clathro)chelates,and porphyrins

Experimental data on the application of metal complexes in radical polymerization of vinyl monomers collected over the recent 15 years have been analyzed and generalized. Special attention has been given to (un)substituted ferrocenes, macrocyclic (clathro)chelates, and iron porphyrinates as well as to the approaches to enhance their catalytic activity in controlled synthesis of macromolecules. The mentioned systems have been compared with each other as well as with selected complexes of other transition metals. It has been shown that the electronic and spatial structures of the metal complexes are related to their efficiency in the radical polymerization reactions.     

Interaction of Co(II), Ni(II) and Cu(II) with dibenzo-substituted macrocyclic ligands incorporating both symmetrically and unsymmetrically arranged N, O and S donors

The synthesis and characterisation of four 17-membered, dibenzo-substituted macrocyclic ligands incorporating unsymmetrical arrangements of their N(3)S(2), N(3)O(2) and N(3)OS (two ligands) donor atoms are described; these rings complete the matrix of related macrocyclic systems incorporating both symmetric and unsymmetric donor sets reported previously. The X-ray structures of three of the new macrocycles are reported. In two of the Cu(II) structures only three of the possible five donor atoms present in the corresponding macrocyclic ligand bind to the Cu(II) site, whereas all five donors are coordinated in each of the remaining complexes. The interaction of Co(II), Ni(II) and Cu(II) with the unsymmetric macrocycle series has been investigated by potentiometric (pH) titration in 95% methanol; X-ray structures of two nickel and three copper complexes of these ligands, each exhibiting 1:1 (M:L) ratios, have been obtained. The results are discussed in the context of previous results for these metals with the analogous 17-membered ring systems incorporating symmetrical arrangements of their donor atoms, with emphasis being given to both the influence of the donor atom set, as well as the donor atom sequence, on the nature of the resulting complexes.     

Synthesis and spectroscopic characterizations of Cu(II) complexes with novel 15‐membered N4 macrocyclic ligand and their utility to obtain CuO nanostructures for efficient degradation of dyes

This paper describes synthesis, characterization and application of a series of Cu(II) complexes with a novel 3‐thioxo‐[1,2,4,5]tetrazocane‐6,8‐dione (N₄) macrocyclic ligand. The complexes were characterized by physicochemical and spectroscopic techniques, such as UV–visible and IR spectroscopies, molar conductance, magnetic susceptibility measurements, and elemental analysis. The data suggest that the mononuclear Cu(II) complexes have a metal‐to‐ligand mole ratio of 1:1 and that the Cu(II) ions are coordinated with the four nitrogen atoms inside the N₄ macrocyclic ring. The experimental anisotropic g‐values indicate that the chloro, nitrato, acetate, and perchlorato complexes have six‐coordinate distorted octahedral behavior, whereas the sulfato complex has five‐coordinate square‐pyramidal geometry. A simple and nontoxic method for preparation of CuO nanoparticles based upon the thermal decomposition of the synthesized Cu(II) complexes has been explored. Finally, the degradation of Rhodamine 6G dye by the catalytic performance of nano‐sized CuO material has been evaluated.     

Complexes of a New N3S2 Macrocycle: Synthesis,Structure and Electrospray Mass Spectrometry

The silver(I) complex of a 15-membered macrocyclic ligand with an N₃S₂ donor set (L¹) has been prepared by the reaction of 2,6-diacetylpyridine with 1,8-diamino-3,6-dithiaoctane in the presence of silver(I) ions. A reduced form (L²) of the ligand, in which the imine groups are converted to amines, was prepared by the reduction of the silver(I) complex by sodium borohydride. The ligand L² has been characterised by various spectroscopic techniques and the copper(II) complex has been prepared. The metal complexes of L¹ and L² have been characterised by electrospray mass spectrometry and UV-visible spectroscopy. The copper(II) complex of L¹ has been synthesised from [AgL¹]⁺ via metal exchange. [CuL¹](ClO₄)₂ crystallises in the orthorhombic space group Pna2₁ with a = 14.374(5) Å, b = 12.947(3) Å, c = 11.824(3) Å with Z= 4. The geometry about the metal centre approximates trigonal bipyramidal with the pyridinyl nitrogen and the sulfur donors in the equatorial positions and the imine nitrogen donors in the axial positions. Metal ion exchange and the relative stabilities of metal complexes of the macrocyclic ligands were studied by electrospray mass spectrometry.     

Quantum-chemical models of the molecular structures of open-chain and macrocyclic <Emphasis Type="Italic">d</Emphasis>-metal chelates with (N,O)- and (N,S)-donor polydentate ligands

The results of quantum-chemical calculations of the molecular structures of d-metal chelate complexes with compartmental and macrocyclic ligands arising as a result of “self-assembly” processes (template synthesis) to form so-called open and closed contours around the complexing agent have been systematized and generalized. In general, for compounds of both the first and second groups, molecular structures with noncoplanar chelate cores and macrocyclic moieties are more characteristic than coplanar ones. The review covers the works of the author and other researchers carried out mainly over the past 20 years     

Synthesis, structural, spectral, thermal and antimicrobial studies of palladium(II), platinum(II), ruthenium(III) and iridium(III) complexes derived from N,N,N,N-tetradentate macrocyclic ligand

Palladium(II), platinum(II), ruthenium(III) and iridium(III) complexes of general stoichiometry [PdL]Cl(2), [PtL]Cl(2), [Ru(L)Cl(2)]Cl and [Ir(L)Cl(2)]Cl are synthesized with a tetradentate macrocyclic ligand, derived from 2,6-diaminopyridine with 3-ethyl 2,4-pentanedione. Ligand was characterized on the basis of elemental analyses, IR, mass, and (1)H NMR and (13)C NMR spectral studies. All the complexes were characterized by elemental analyses, molar conductance measurements, magnetic susceptibility measurements, IR, mass, electronic spectral techniques and thermal studies. The value of magnetic moments indicates that all the complexes are diamagnetic except Ru(III) complex which shows magnetic moments corresponding its one unpaired electron. The macrocyclic ligand and all its metal complexes were also evaluated in vitro against some plant pathogenic fungi and bacteria to assess their biocidal properties.     

手性1，4-二胺构建的双核铜[2+2]席夫碱大环化合物：制备和催化研究

Dinuclear copper(Ⅱ) complexes of [2+2] macrocyclic Schiff bases have been prepared from chiral 1,4-diamines using sodium ions as template. Catalytic investigation on the titled complexes has been carried out on model reactions (asymmetric sulfoxidation and asymmetric oxidative-coupling reactions).     

Novel copper(II) homobinuclear macrocyclic complexes: cyclic voltammetry, biological properties and spectral studies

A series of five new copper(II) macrocyclic complexes have been synthesized by template condensation. The bonding and stereochemistry of the complexes have been characterized by elemental analysis, molar conductance, magnetic susceptibility, IR, UV-visible, EPR spectral studies and electrochemical properties. g-Values are calculated for all of the complexes in polycrystalline form as well as in DMSO solution. The magnetic and spectral data indicate square planar geometry for all the complexes. Cyclic voltammograms for all the complexes are similar and involve two quasi-reversible redox processes. Cu(II)Cu(II)<=>Cu(II)Cu(I)<=>Cu(I)Cu(I). Their biological properties have also been studied. The macrocyclic complexes show more anti-bacterial than controlled one. The anti-bacterial activities of the compounds were tested against Streptococcus fecalis and Escherichia coli with different concentrations.     

Preparation and characterisation of copper,cobalt and nickel complexes of tetradentate N6 macrocyclic ligand

Macrocyclic complexes of copper, nickel and cobalt were synthesised via template reactions. These 14-membered N₆ tetradentate macrocyclic complexes were characterised by magnetic, conductance, electronic and IR spectral studies. The macrocyclic ligand coordinates through the four azomethine nitrogen atoms which are bridged by 2,3-butanedione, moieties, but far IR spectra suggest that the pyridine nitrogens are not coordinated. These macrocyclic complexes are considered to have distorted octahedral configurations.     

Manganese(II), Cobalt(II), and Nickel(II) Perchlorate Complexes Containing N,O Donor Macrocyclic Ligands

Mononuclear macrocyclic complexes of manganese(II ), cobalt(II ) and nickel(II ) perchlorate using 10 different oxaazamacrocyclic ligands (L¹ — L¹⁰) have been prepared and characterized. The complexation reactions with the diiminic ligands were obtained by template condensation of the appropriate dialdehyde and diamine precursors; the reduced macrocycle complexes were synthesized using a direct route. The complexes have been characterized by elemental analyses, molar conductivity, mass spectrometry, IR, UV‐vis spectroscopy, diffuse reflectance and magnetic susceptibility measurements.     

Spectral studies with coordination behaviour of (NO3) and (NCS) anions and EPR parameters of chromium(III) complexes which have different chromospheres macrocyclic ligands: synthesis and electronic spectroscopy

New macrocyclic ligands were prepared and chromium(III) stability in the marcrocyclic cavities are reported. Two of them have four-coordinate [N2O2]:[N4], third one has five-coordinate [N2O2S] and the last one has six-coordinate [N4O2] donor macrocyclic cavities. These macrocyclic ligands have been synthesized with their chromium(III) complexes which have mononuclear nature and their structural features have been discussed on the basis of: elemental analysis, magnetic moment, electronic, IR, 1H NMR, and EPR spectral studies. All the chromium(III) complexes show magnetic moments in the range of 3.74-3.80 B.M. corresponding to high-spin configuration. However, the interaction of oxygen to the chromium ion in complexes is much weaker than that of other donor atoms. The spin-orbit coupling parameter, z, gives no significance because the splitting of doublet transition lines are too large to be explained by spin-orbit coupling. The beta values (0.75-0.79) indicate the covalent character, which is due to the presence of sigma bond between the metal/ligand. lambda values indicate that the complexes under study have substantial covalent character and their g-values have also been calculated by using spin-orbital coupling constant (lambda).     

Reaction kinetics in replacement of zinc ions by copper ions in complexes with cyclic and noncyclic tetramines

A kinetic study has been made of reactions of zinc ion replacement by copper in complexes with macrocyclic and noncyclic tetramines. The activation parameters of these processes have been determined, and reaction mechanisms are proposed. A kinetic macrocyclic effect has been found in reactions of central atom replacement in tetraazamacrocyclic complexes of zinc.Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 21, No. 2, pp. 175–182, March–April, 1985.     

Electronic structure and redox properties of macrocyclic complexes [M(TAAB)]n+ (M = Ni,Cu)

The SCF-LCAO-MO method in the CNDO approximation has been used in calculating the electronic structure of complexes of nickel and copper with the macrocyclic ligand TAAB, complexes with the general formula [M(TAAB)]ⁿ⁺ (n=0–3). From an analysis of the distribution of electron density and populations of the AOs of the central ion in these complexes, it has been established that the process of reduction of nickel compounds is accompanied by an increase in electron density on the carbon atoms of the macrocyclic ligand, whereas in the reduction of [Cu(TAAB)]²⁺ a substantial increase is observed in the populations of the 3d AOs of the central ion, i.e., it is reduced. The difference in behavior of the complexes upon reduction is due to differences in the electronic configuration of the central ion. The structure and orbital composition of the frontier MOs have been analyzed, and it has been shown that in the reduced complexes of nickel [Ni(TAAB)], which have strong nucleophilic properties, not only the central ion may act as a nucleophilic center, but also the carbon atoms of the macrocyclic ligand.Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 23, No. 4, pp. 421–428, July–August 1987.     

Spectroscopic, cyclic voltammetric and biological studies of transition metal complexes with mixed nitrogen-sulphur (NS) donor macrocyclic ligand derived from thiosemicarbazide

The complexation of new mixed thia-aza-oxa macrocycle viz., 2,12-dithio-5,9,14,18-tetraoxo-7,16-dithia-1,3,4,10,11,13-hexaazacyclooctadecane containing thiosemicarba-zone unit with a series of transition metals Co(II), Ni(II) and Cu(II) has been investigated, by different spectroscopic techniques. The structural features of the ligand have been studied by EI-mass, (1)H NMR and IR spectral techniques. Elemental analyses, magnetic moment susceptibility, molar conductance, IR, electronic, and EPR spectral studies characterized the complexes. Electronic absorption and IR spectra of the complexes indicate octahedral geometry for chloro, nitrato, thiocyanato or acetato complexes. The dimeric and neutral nature of the sulphato complexes are confirmed from magnetic susceptibility and low conductance values. Electronic spectra suggests square-planar geometry for all sulphato complexes. The redox behaviour was studied by cyclic voltammetry, show metal-centered reduction processes for all complexes. The complexes of copper show both oxidation and reduction process. The redox potentials depend on the conformation of central atom in the macrocyclic complexes. Newly synthesized macrocyclic ligand and its transition metal complexes show markedly growth inhibitory activity against pathogenic bacterias and plant pathogenic fungi under study. Most of the complexes have higher activity than that of the metal free ligand.