The Stability Constants of Complexes of BDBPH- Metals and Species Distributions

The study on the design and synthesis of model compounds for metalloproteins has been a subject of extensive investigation1. During the last decade, a number of synthetic structural models for some kinds of metalloproteins with several types of ligands have been reported in literature2,3,4. We have recently reported a new 24-membered hexaazadiphenol macrocyclic ligand, 3,6,9,17,20,23-hexaaza-29,30-dihydroxy-13,27-dimethyl-tricyclo [23,3,1,111,15] triaconta-1 (28),11,13,15 (30),25,26-hexaene,…     

Models of molecular structures of macrocyclic metal chelates in the ternary 4<Emphasis Type="Italic">d</Emphasis> M(II) ion–ethanedithioamide–ethanedial systems according to quantum-chemical DFT calculations

The thermodynamic and geometric parameters of the molecular structures of macrotricyclic Tc(II), Ru(II), Rh(II), Pd(II), Ag(II), and Cd(II) complexes with the (NSSN)-coordination of the ligand donor sites formed by complexation of the corresponding M(II) ions with ethanedithioamide H₂N–C(=S)–C(=S)–NH₂ and ethanedial HC(=O)–CH(=O) have been calculated by the OPBE/TZVPQZP hybrid density functional theory method with the use of the Gaussian09 program package. The bond lengths and bond angles in these complexes have been reported, and it has been stated that the Rh(II) and Ag(II) complexes are nearly planar, the Tc(II), Pd(II), and Cd(II) complexes are slightly nonplanar, while the Ru(II) complex exhibits a rather considerable deviation from coplanarity. The additional five-membered chelate ring resulting from template cross-linking is either strictly planar (in the Tc(II), Rh(II), Pd(II), and Ag(II) complexes) or nearly planar (in the Ru(II) and Cd(II) complexes).     

Synthesis, spectroscopic characterization and magnetic properties of homo- and heterodinuclear complexes of transition and non-transition metal ions with a new Schiff base ligand

Four homodinuclear complexes of Ni(II)-Ni(II), Cu(II)-Cu(II), Co(II)-Co(II) and Co(III)-Co(II) and five heterodinuclear complexes of Co(III)-Zn(II), Co(III)-Cu(II), Co(III)-Ni(II), Cu(II)-Zn(II) and Zn(II)-Cu(II) with the octadentate Schiff base compartmental ligand 1,8-N-bis(3-carboxy)disalicylidene-3,6-diazaoctane-1,8-diamine (H4fsatrien) have been synthesized. The complexes have been characterized with the help of elemental analyses, molecular weights, molar conductances, magnetic susceptibilities and spectroscopic (UV-vis, IR, ESR) data. Cryomagnetic data also helped to elucidate the structural features of the Cu(II) complexes.     

N-亚水杨基亮氨酸3d金属配合物的合成及薄层色谱与紫外光谱研究

合成了亮氨酸水杨醛希夫碱及其与Ｍｎ（Ⅱ）,Ｃｏ（Ⅱ）,Ｎｉ（Ⅱ）,Ｃｕ（Ⅱ）,Ｚｎ（Ⅱ）的配合物。元素分析和摩尔电导测定的结果证明,亮氨酸水杨醛希夫碱３ｄ金属配合物配位比为１１,配合物在ＤＭＦ中为非电解质。在硅胶Ｇ板上,以乙酸乙酯－甲醇－丙酮－水－乙酸（４．４４３．３３２．２２０．２５０．１２,Ｖ／Ｖ）为流动相,研究了配合物的薄层色谱行为,各组分配合物的比移值Ｒｆ值相差较大,得到满意的分离,且Ｒｆ值按下列顺序递增Ｍｎ＜Ｚｎ＜Ｎｉ＜Ｃｕ＜Ｃｏ。讨论了系列配合物薄层色谱Ｒｆ与紫外光谱Ｒ带λｍａｘ变化关系的规律     

Formation of 1 D and 3 D coordination polymers in the solid state induced by mechanochemical and annealing treatments: bis(3-cyano-pentane-2,4-dionato) metal complexes

Bis(3-cyano-pentane-2,4-dionato) (CNacac) metal complex, [M(CNacac)(2)], which acts as both a metal-ion-like and a ligand-like building unit, forms supramolecular structures by self-assembly. Co-grinding of the metal acetates of Mn(II), Co(II), Ni(II), Cu(II) and Zn(II) with CNacacH formed a CNacac complex in all cases: mononuclear complex was formed in the cases of Mn(II), Cu(II) and Zn(II), whereas polymeric ones were formed in the cases of Fe(II), Co(II) and Ni(II). Subsequent annealing converted the mononuclear complexes of Mn(II), Cu(II) and Zn(II) to their corresponding polymers as a result of dehydration of the mononuclear complexes. The resultant Mn(II), Fe(II), Co(II), Ni(II) and Zn(II) polymeric complexes had a common 3 D structure with high thermal stability. In the case of Cu(II), a 1 D polymer was obtained. The Mn(II), Cu(II) and Zn(II) polymeric complexes returned to their original mononuclear complexes on exposure to water vapour but they reverted to the polymeric complexes by re-annealing. Co-grinding of metal chlorides with CNacacH and annealing of the mononuclear CNacac complexes prepared from solution reactions were also examined for comparison. [Mn(CNacac)(2)(H(2)O)(2)], [M(CNacac)(2)(H(2)O)] (M=Cu(II) and Zn(II)) and [M(CNacac)(2)](infinity) (M=Mn(II), Fe(II) and Zn(II)) are new compounds, which clearly indicated the power of the combined mechanochemical/annealing method for the synthesis of varied metal coordination complexes.     

Spectral, IR and magnetic studies of Mn(II), Co(II), Ni(II) and Cu(II) complexes with pyrrole-2-carboxyaldehyde thiosemicarbazone (L)

Mn(II), Co(II), Ni(II) and Cu(II) complexes are synthesized with thiosemicarbazone (L) derived from pyrrole-2-carboxyaldehyde. These complexes are characterized by elemental analysis, molar conductance, magnetic susceptibility measurement, mass, IR, electronic and EPR spectral studies. The molar conductance measurement of the complexes in DMSO indicates that the complexes are non-electrolyte except Co(L)2(NO3)2 and Ni(L)2(NO3)2 complexes which are 1:2 electrolyte. All the complexes are of high-spin type. On the basis of spectral studies an octahedral geometry may be assigned for Mn(II), Co(II) and Ni(II) complexes except Co(L)2(NO3)2 and Ni(L)2(NO3)2 which are of tetrahedral geometry. A tetragonal geometry may be suggested for Cu(II) complexes.     

Anticancer activity, attenuation on the absorption of calcium in mitochondria, and catalase activity for manganese complexes of N-substituted di(picolyl)amine

In order to find multifunction anticancer complexes, three Mn(II) complexes of N-substituted di(2-pyridylmethyl)amine were characterized and used as agents to interfere with the functions of mitochondria and the metabolite of O(2) in cancer cells. It was found that carboxylate-bridged dimanganese(II) systems are good models of catalase and exhibit good inhibition of the proliferation of U251 and HeLa cells. The inhibiting activity of these manganese(II) complexes on the tumor cells in vitro was related to their disproportionating H(2)O(2) activity. The reaction of carboxylate-bridged dimanganese Mn(II) complex with H(2)O(2) forms a stable Mn(III)-(μ-O)(2)-Mn(IV) complex. Extensive experimental results show that chloride-bridged dimanganese(II) complexes could inhibit the swelling of calcium(II) overloaded mitochondria, and carboxylate-bridged manganese(II) complexes enhance the swelling of calcium(II) overloaded mitochondria. These results indicate that the interactions between Mn(II) complexes of N-substituted di(picolyl)amine and mitochondria are influenced by the structure and conformation of the complexes. Mn(II) complexes of N-substituted di(picolyl)amine could be developed as multifunctional anticancer complexes to interfere with the absorption of calcium(II) in mitochondria and the metabolite of O(2) through the H(2)O(2) or ROS involved signaling induced apoptosis of cancer cells.     

Metal complexes of porphycene,corrphycene, and hemiporphycene: stability and coordination chemistry

Porphyrin (P), porphycene (Pc), corrphycene (Cn), and hemiporphycene (Hpc) represent a series of well defined "4-N in" constitutional porphyrin isomers. These isomers, in the form of their octaethyl derivatives, represent a congruent set of porphyrinoids whose properties can be compared. In this study we report how variations in electronic structure and nitrogen-core size in the free-base forms of these four systems are reflected in the properties of their corresponding metal complexes. Specifically, the effects that these differences have on the axial ligation properties of the Zn(II), Mg(II), Ni(II), and Co(II) complexes of P, Pc, Cn, and Hpc in toluene using pyridine as the axial ligand are detailed. Also reported are the relative stabilities of these complexes under acidic conditions. It is shown that for the zinc, magnesium, and cobalt complexes, there are distinct differences in the ability to maintain four-, five-, or six-coordinate geometries in the presence of similar concentrations of pyridine. By contrast, no apparent differences in axial ligand binding affinity are seen for the four nickel complexes. Little difference in stability was likewise seen when these same complexes were subject to acid-mediated demetallation, with all four falling into stability class II, according to the accepted porphyrin stability ranking system. High stabilities were also seen in the case of the cobalt complexes, with the Pc and Cn complexes being of stability class III and the P and Hpc derivatives falling into stability class II. The Zn(II) and Mg(II) complexes were all far less stable than the corresponding Ni(II) and Co(II) complexes. In this case, semiquantitative analyses of the rate of acid-induced decomposition revealed the following stability sequence P>Cn>Hpc>Pc for both the Zn(II) and Mg(II) complexes. Single-crystal X-ray diffraction structures were solved for the Zn(II), Mg(II), and Ni(II) complexes of the octaethyl derivatives of Hpc, Cn, and Pc as well as a Co(II) octamethylcorrphycene and are reported as part of this study. These solid-state structures confirm four-coordinate species for the Ni(II) complexes, four- and five-coordinate species for the Mg(II) and Zn(II) complexes, and a six-coordinate species for the lone Co(II) complex.     

Synthesis and antitumor activities of alkyl-1,4-butanediamine Pt(II) complexes having seven-membered ring structure

Novel alkyl-1,4-butanediamine Pt(II) complexes having a seven-membered ring structure were synthesized and characterized by fast atom bombardment mass and infrared spectra and elemental analysis. Their antitumor activities in vivo toward lymphoid leukemia L1210 and Lewis lung carcinoma LL were studied in the case where the leaving group was either dichloride or cyclobutane-1,1-dicarboxylate. 1,4-Butanediamine Pt(II) complexes (seven-membered ring) showed higher antitumor activities than those of ethylenediamine Pt(II) (five-membered ring) and 1,3-propanediamine Pt(II) (six-membered ring) complexes toward L1210 for both leaving groups. Alkyl-1,4-butanediamine Pt(II) complexes showed high antitumor activities toward L1210, except for 1,1-dimethyl-1,4-butanediamine Pt(II) complexes. In particular, 2,2-dimethyl-1,4-butanediamine and 2,3-dimethyl-1,4-butanediamine Pt(II) complexes exhibited excellent antitumor activities with T/C% values higher than 300. None of the dichloro Pt(II) complexes showed antitumor activities toward LL, but the cyclobutane-1,1-dicarboxylato Pt(II) complexes, which were moderately active toward L1210 with T/C% values around 200, also showed high antitumor activities toward LL with T/C% values of more than 200. Alkyl-1,4-butanediamine Pt(II) complexes with a seven-membered ring structure were found to be stable and to have antitumor activities in vivo.     

Spectroscopic characterization of tetradentate macrocyclic ligand: its transition metal complexes

Manganese(II), cobalt(II), nickel(II) and copper(II) complexes are synthesized with a novel tetradentate ligand viz. 1,3,9,11-tetraaza-4,8,12,16-tetraoxo-2,6,10,14-tetrathiacyclohexadecane (L) and characterized by the elemental analysis, molar conductance measurements, magnetic susceptibility measurements, electron impact mass, 1H NMR, IR, electronic and EPR spectral studies. The molar conductance measurements of the complexes in DMSO correspond to be nonelectrolytic nature for Mn(II), Co(II) and Cu(II) while 1:2 electrolytes for Ni(II) complexes. Thus these complexes may be formulated as [M(L)X2] and [Ni(L)]X2 (where M: Mn(II), Co(II), and Cu(II) and X = Cl- and NO3-). On the basis of IR, electronic and EPR spectral studies an octahedral geometry has been assigned for Mn(II) and Co(II) complexes, square-planar for Ni(II) whereas tetragonal for Cu(II) complexes. The ligand and its complexes were also evaluated against the growth of bacteria and pathogenic fungi in vitro.     

Synthesis of iron(II), manganese(II) cobalt(II) and ruthenium(II) complexes containing tridentate nitrogen ligands and their application in the catalytic oxidation of alkanes

A series of Fe(II), Mn(II), Co(II) and Ru(II) complexes containing bis(imino)pyridine or bis(amino)pyridine ligands and weakly coordinating triflate (OTf-) or non-coordinating SbF6- anions have been prepared. The complexes have been fully characterized including several solid-state structure analyses. Two unusual mono-chelate six-coordinate bis(imino)pyridine Fe(II) and Mn(II) complexes have been observed. The catalytic properties of the complexes for the oxidation of cyclohexane with H2O2 have been evaluated. Only the Fe(II) complexes have shown catalytic activity, which is mainly due to Fenton-type free radical auto-oxidation.     

Salisaldehyde-2-aminobenzimidazole schiff base complexes of Fe(III), Co(II), Ni(II), Cu(II), Zn(II) and Cd(II)

New metal complexes of Fe(III), Co(II), Ni(II), Cu(II), Zn(II) and Cd(II) with salicylidine-2-aminobenzimidazole (SABI) are synthesized and their physicochemical properties are investigated using elemental and thermal analyses, IR, conductometric, solid reflectance and magnetic susceptibility measurements. The base reacts with these metal ions to give 1:1 (Metal:SABI) complexes; in cases of Fe(III), Co(II), Cu(II), Zn(II) and Cd(II) ions; and 1:2 (Metal:SABI) complexes; in case of Ni(II) ion. The conductance data reveal that Fe(III) complex is 2:1 electrolyte, Co(II) is 1:2 electrolyte, Cu(II), Zn(II) and Cd(II) complexes are 1:1 electrolytes while Ni(II) is non-electrolyte. IR spectra showed that the ligand is coordinated to the metal ions in a terdentate mannar with O, N, N donor sites of the phenloic -OH, azomethine -N and benzimidazole -N3. Magnetic and solid reflectance spectra are used to infer the coordinating capacity of the ligand and the geometrical structure of these complexes. The thermal decomposition of the complexes is studied and indicates that not only the coordinated and/or crystallization water is lost but also that the decomposition of the ligand from the complexes is necessary to interpret the successive mass loss. Different thermodynamic activation parameters are also reported, using Coats-Redfern method. This revised version was published online in July 2006 with corrections to the Cover Date.     

Stereochemistry of new nitrogen containing heterocyclic aldehyde. Part XI. Novel ligational behaviour of quinoline as chelate ligand toward transition metal ions

Novel complexes of Mn(II), Fe(II), Co(II), Ni(II), Cu(II), Zn(II) and UO2(II) with a new Schiff base derived from 8-hydroxy-7-quinolinecarboxaldehyde and 2-aminoethanethiol (LH2) (system name: 2-(8-hydroxy-7-carboxalimino)ethanethiol.) have been prepared and characterized on the basis of analytical, thermal, magnetic moment, infrared, electronic, NMR and EPR spectral data. From the analytical, NMR and thermal data and stoichiometry of the complexes indicate that LH2 act as a dibasic tridentate ligand with ONS donors towards all the metal ions. The magnetic moment, electronic and EPR spectral data commensurate that the Mn(II), Fe(II), Ni(II) and UO2(II) complexes are dimeric with octahedral configuration while the Cu(II) and Zn(II) complexes are monomeric with square-planar and tetrahedral geometries, respectively. Various ligand field parameters Dq, B and beta for complex 5 was calculated. The complexes 3+4 have lower symmetries and the amount of distortion in terms of DT/DQ applying NSH "Hamiltonian Theory" has been evaluated which indicate that the complexes are moderately distorted.     

Co(II) and Ni(II) complexes with Schiff base ligands: Synthesis,characterization, and biological activity

The ligands, 1-acetylferrocenehydrazinecarboxamide (HL¹) and 1-acetylferrocenehydrazinecarbothioamide (HL²), and their Ni(II) and Co(II) complexes were synthesized. The properties of the synthesized compounds were determined by the elemental and spectroscopic analyses. Ni(II) and Co(II) acetates interact with the ligands at the molar ratios 1 : 1 and 1 : 2 to give coloured products. The complexes have octahedral geometry. The ligands are coordinated to Co(II) and Ni(II) centers via the azomethine nitrogen and thiolic sulfur /enolic oxygen atom. The ligands and their Co(II) and Ni(II) complexes were screened for antibacterial and antifungal activities. The Co(II) and Ni(II) complexes show enhanced inhibitory activity as compared to their parent ligands. The DNA cleavage activity of the Co(II) and Ni(II) complexes was determined by gel electrophoresis. It was shown that the complexes have better cleavage activity than the ligands. The antioxidant activity of the complexes was also evaluated and used to examine their scavenging ability on hydrogen peroxide.     

Synthesis and characterization of iron(III), manganese(II), cobalt(II), nickel(II), copper(II) and zinc(II) complexes of salicylidene-N-anilinoacetohydrazone (H2L1) and 2-hydroxy-1-naphthylidene-N-anilinoacetohydrazone (H2L2)

Salicylidene-N-anilinoacetohydrazone (H(2)L(1)) and 2-hydroxy-1-naphthylidene-N-anilinoacetohydrazone (H(2)L(2)) and their iron(III), manganese(II), cobalt(II), nickel(II), copper(II) and zinc(II) complexes have been synthesized and characterized by IR, electronic spectra, molar conductivities, magnetic susceptibilities and ESR. Mononuclear complexes are formed with molar ratios of 1:1, 1:2 and 1:3 (M:L). The IR studies reveal various modes of chelation. The electronic absorption spectra and magnetic susceptibility measurements show that the iron(III), nickel(II) and cobalt(II) complexes of H(2)L(1) have octahedral geometry. While the cobalt(II) complexes of H(2)L(2) were separated as tetrahedral structure. The copper(II) complexes have square planar stereochemistry. The ESR parameters of the copper(II) complexes at room temperature were calculated. The g values for copper(II) complexes proved that the Cu-O and Cu-N bonds are of high covalency.     

Electronic, epr and magnetic studies of Co(II), Ni(II) and Cu(II) complexes with thiosemicarbazone (L1) and semicarbazone (L2) derived from pyrole-2-carboxyaldehyde

Co(II), Ni(II) and Cu(II) complexes are synthesized with thiosemicarbazone (L(1)) and semicarbazone (L(2)) derived from pyrole-2-carboxyaldehyde. These complexes are characterized by elemental analysis, molar conductance, magnetic susceptibility measurements, mass, IR, electronic and EPR spectral studies .The molar conductance measurements of the complexes in DMSO correspond to non-electrolytic nature except Co(L1)2(NO3)2 and Ni(L1)2(NO3)2 complexes which are 1:2 electrolytes. All the complexes are of high-spin type. On the basis of spectral studies an octahedral geometry may be assigned for Co(II) and Ni(II) complexes except Co(L1)2(NO3)2 and Ni(L1)2(NO3)2 which are of tetrahedral geometry. A tetragonal geometry may be suggested for Cu(II) complexes.     

Molecular structures of macrotricyclic 4<Emphasis Type="Italic">d</Emphasis> M(II) chelates with the (NNNN)-donor ligand 2,7-dithio-3,6-diazaoctadiene-3,5-dithioamide-1,8 according to quantum-chemical density functional theory calculations

The thermodynamic and geometric parameters of the molecular structures of macrotricyclic Mo(II), Ru(II), Rh(II), Pd(II), Ag(II), and Cd(II) complexes with the tetradentate ligand 2,7-dithio-3,6-diazaoctadiene-3,5-dithioamide-1,8 with the (NNNN) coordination of the donor centers have been calculated by the hybrid density functional theory (DFT) method in the OPBE/TZVPQZP approximation with the use of the Gaussian09 program package. The Pd(II), Ag(II), and Cd(II) complexes are exactly planar, the Tc(II) and Rh(II) complexes exhibit slight deviations from coplanarity, while the Mo(II) and Ru(II) complexes have rather significant deviations. The five-membered chelate rings in the complexes are either strictly planar or deviate slightly (no more than by 5°) from coplanarity.     

Spectroscopic studies of transition metal complexes with a N-donor tetradentate(N4) 12-membered macrocylic ligand

Chromium(III), manganese(II), iron(III), cobalt(II), nickel(II), copper(II), ruthenium(III), iridium(III), palladium(II) and platinum(II) complexes were synthesized with a 12-membered 1,4,7,10-tetraazadodeca-5,6,11,12-tetraene macrocylic ligand (L) and characterized by elemental analysis, molar conductance, magnetic susceptibility, IR, electronic, EPR and M?ssbauer [Fe(III)] spectral studies. The molar conductance measurements of all the complexes in DMF solution correspond to non-electrolytic nature for M(L)Cl2 complexes [where M=Mn(II), Co(II), Ni(II), Cu(II)], 1:1 electrolytes for M'(L)Cl3 complexes [where M'=Cr(III), Fe(III), Ru(III) and Ir(III)] and 1:2 electrolytes for M'(L)Cl2 complexes [where M'=Pd(II) and Pt(II)]. Thus, the complexes may be formulated as [M(L)C1(2)], [M'(L)C1(2)]C1 and [M'(L)]C1(2), respectively [where L=ligand]. All complexes were of the high-spin type and found to have six-coordinate octahedral geometry except the Pd(II) and Pt(II) complexes which were four coordinate, square planar and diamagnetic.     

Spectral studies on Co(II), Ni(II) and Cu(II) complexes with thiosemicarbazone (L1) and semicarbazone (L2) derived from 2-acetyl furan

Co(II), Ni(II) and Cu(II) complexes are synthesized with thiosemicarbazone (L1) and semicarbazone (L2) derived from 2-acetyl furan. These complexes are characterized by elemental analysis, molar conductance, magnetic susceptibility measurements, mass, IR, electronic and EPR spectral studies. The molar conductance measurements of the complexes in DMSO correspond to non-electrolytic nature except Ni(L)2(NO3)2, which is 1:2 electrolyte. All the complexes are of high-spin type. On the basis of spectral studies an octahedral geometry may be assigned for Co(II) and Ni(II) complexes except nitrato complexes of Ni(II) which is of tetrahedral geometry, whereas tetragonal geometry for Cu(II) complexes.     

Transition Metal Complexes of Dis(thiosemicarbazone): Synthesis and Spectral,and Antifungal Studies

Mn(II), Co(II), Ni(II), and Cu(II) complexes have been synthesized with benzil bis(thiosemicarbazone) (L) and characterized by elemental analyses, molar conductance measurements, magnetic susceptibility measurements, thermogravimetric studies, infrared (IR), electronic, and electron paramagnetic resonance (eEPR) spectral studies. The molar conductance measurements of the complexes in DMF correspond to the non-electrolytic nature of the complexes. Thus these complexes may be formulated as [M(L)X₂] (where M = Mn(II), Co(II), Ni(II), Cu(II) and X = Cl^? and NO₃ ^?). On the basis of IR, electronic, and EPR spectral studies, an octahedral geometry has been assigned for Mn(II), Co(II), and Ni(II) complexes, whereas a tetragonal geometry for the Cu(II) complexes is presumed. The free ligand and its metal complexes were tested against the phytopathogenic fungi (i.e., Rhizoctonia baticola, Alternaria alternata) in vitro.