Isostructural M2L4 molecular capsules with anthracene shells: synthesis, crystal structures, and fluorescent properties

An isostructural series of M(2)L(4) molecular capsules quantitatively self-assembled from two M(II) ions (M=Zn, Cu, Pt, Pd, Ni, Co, and Mn) and four bent ligands with embedded anthracene fluorophores. X-ray crystallographic analysis (for M=Zn, Cu, Ni, and Pd) confirmed the formation of closed-shell structures in which the large interior cavities inside the molecular capsules (about 1 nm) were shielded by eight anthracene panels. Analysis of the Zn(II) and Cu(II) structures showed the inclusion of an unusual triad guest cluster; four MeCN molecules, one water molecule, and one CF(3)SO(3)(-) ion were located inside the cavities. Full characterization by NMR spectroscopy and MS (ESI-TOF) demonstrated that the molecular capsules were quite stable and persist in solution. The fluorescence properties of the isostructural capsules were strongly dependent on the identity of the metal species: the Zn(II) capsule emitted strong blue fluorescence with a high quantum yield (Φ=0.8), in sharp contrast to the weakly emissive Ni(II) and Mn(II) capsules and the completely non-emissive Pd(II), Pt(II), and Co(II) capsules. On the other hand, the Cu(II) capsule exhibited solvatochromism and solvent-dependent emission behavior; blue emission of the capsule was "on" in DMSO but "off" in MeCN.     

2,2''''—双〔2—(邻甲酰肟苯氧基)乙基〕醚与过渡金属配合物的合成及性质研究

含氮配位原子的希夫碱型化合物在分析化学、合成化学、药学等方面有广泛的应用。近十多年来,随着新药物的研制和生物无机化学的发展,其研究正在不断深入。肟类化合物在结构上与希夫碱型化合物主要不同之处是在于它与氮原子相连的基团是羟基,它在适当的条件下可参与金属配位或形成氢键,研究其配位模式有较重要的理论意义。我们合成了一个新的含醚氧链的双肟化合物,2,2＇—双[2—(邻甲酰肟苯氧基)乙基]醚(H_2BFO)。本     

Late first-row transition-metal complexes of texaphyrin

The preparation of first-row transition-metal complexes of texaphyrin, a porphyrin-like, monoanionic penta-aza macrocyclic ligand, is reported. Specifically, the synthesis of organic-soluble Mn(II) (1), Co(II) (2), Ni(II) (3), Zn(II) (4), and Fe(III) (5) texaphyrin derivatives and their water-soluble counterparts (6-10) from appropriate metal-free, nonaromatic macrocyclic precursors is described. It was found that metal cations of sufficient reduction potential could act to oxidize the nonaromatic macrocyclic precursor in the course of metal insertion. Complexes were characterized by X-ray diffraction analysis, electrochemistry, flash photolysis, and EPR spectroscopy. The structural and electronic properties of these "expanded porphyrin" complexes are compared with those of analogous porphyrins. Notably, the texaphyrin ligand is found to support the complexation of cations in a lower valence and a higher spin state than do porphyrins. Interactions between the coordinated cation and the ligand pi system appear to contribute to the overall bonding. Texaphyrin complexes of Mn(II), Co(II), and Fe(III) in particular may possess sufficient aqueous stability to permit their use in pharmaceutical applications.     

Combinatorial electrochemical synthesis and characterization of tungsten-based mixed-metal oxides

Automated systems for electrochemical synthesis and high-throughput screening of photoelectrochemical materials were developed and used to prepare tungsten-based mixed-metal oxides, W(n)O(m)M(x) [M = Ni, Co, Cu, Zn, Pt, Ru, Rh, Pd, and Ag], specifically for hydrogen production by photoelectrolysis of water. Two-dimensional arrays (libraries) of diverse metal oxides were synthesized by automated cathodic electrodeposition of the oxides on Ti foil substrates. Electrolytes for the mixed oxides were prepared from various metal salts added to a solution containing tungsten stabilized as a peroxo complex. Electrodeposition of the peroxo-stabilized cations gave rise to three distinguishable oxide groups: (1) mixed-metal oxides [Ni], (2) metal-doped tungsten oxides [Pt, Ru, Rh, Pd, Ag], and (3) metal-metal oxide composites [Co, Cu, Zn]. The oxides typically showed n-type semiconducting behavior. Automated measurement of photocurrent using a scanning photoelectrochemical cell showed the W-Ni mixed oxide had the largest relative zero bias photocurrent, particularly at a low Ni concentration (5-10 atomic percent Ni). Pt and Ru were also found to increase the photoactivity of bulk tungsten oxide at relatively low concentrations; however, at concentrations above 5 atomic percent, crystallization of WO(3) was inhibited and photoactivity was diminished. Addition of Co, Cu, and Zn to WO(3) was not found to improve the photoelectrochemical activity.     

Catalytic effects of peroxidase-like metalloporphyrins on the fluorescence reaction of homovanillic acid with hydrogen peroxide

Summary The catalytic effects of peroxidase-like metalloporphyrins (Me-P) on the fluorescence reaction of homovanillic acid with hydrogen peroxide have been studied. These metalloporphyrins are the complexes of Mn with tetrakis(carboxyphenyl)porphyrin (TPPC) and trikis(sulfophenyl)porphyrin(TPPS₃), Fe, Co, Ni, Cu, Zn, Ag and Sn with tetrakis(sulfophenyl)porphyrin(TPPS₄), and Rh, Pt and Pd with tetrakis(N-methylpyridiniumyl)porphyrin-(TMPyP) and hemin. The complexes of Mn, Fe, Co, Rh and Pt with porphyrins catalyzed the formation of the fluorescence product, while the complexes of Ni, Cu, Zn, Ag, Sn and Pd did not. Traces of hydrogen peroxide and glucose can be determined using the metalloporphyrins. The characteristics of peroxidase-like metalloporphyrins have been compared with those of horseradish peroxidase (HRP).     

Adsorption behaviour of a number of metals on weakly basic ion-exchangers in methanol-hydrochloric acid mixtures

Many metals are not strongly adsorbed on DEAE-cellulose from aqueous hydrochloric acid media. However, some metals can be adsorbed on DEAE-cellulose from methanol-hydrochloric acid media. Distribution coefficients of Zn, Cd, Hg(II) and Bi(III), which show pronounced adsorption, are presented as functions of the methanol and the acid concentrations. Differences in the distribution coefficient between the four metals and a considerable number of other metals are large enough to permit good separations on columns. Among the platinum group metals, Pd(II), Ir(IV) and Pt(IV) are adsorbed from the mixed solvents and may be separated from large quantities of base metals such as Fe(III), Co(II), Ni and Cu(II).     

Synthesis, characterization, and electrochemical studies of beta,beta'-fused metallocenoporphyrins

Beta,beta'-Fused monoruthenocenylporphyrins, Cp*Ru(III)[1,2-[M(II)-5,10,15,20-tetrakis(3,5-di-tert-butylphenyl)-porphyrinato]-3-methyl-cyclopentadienide] (M = Ni (20), Cu (21), Zn (22)), and bisferrocenoporphyrins, Fe(II) bis[1,2-[M(II)-5,10,15,20-tetraphenylporphyrinato]-3-methyl-cyclopentadienide] (M = Ni (24), Cu (25), Zn (26)), were synthesized and characterized. A novel synthetic approach to beta,beta'-fused porphyrins through Pd(0)-catalyzed [3 + 2] cycloaddition was implemented in this work. UV-vis spectra of these compounds show largely broadened and red-shifted bands (relative to their precursors) indicating potential electronic communication between the attached organometallic moiety and the porphyrin core. The electrochemistry of these molecules suggests significant electronic interactions between the metallocene and metalloporphyrin in molecules 20 and 24. The crystal structure of the bisferrocenoporphyrin 26, Fe(II) bis[1,2-[Zn(II)-5,10,15,20-tetraphenylporphyrinato]-3-methyl-cyclopentadienide], was determined: [Cp2Fe[ZnTPP(THF)]2][Cp2Fe[ZnTPP(THF)ZnTPP(MeOH)]].3MeOH.6THF, M = 3804.35, monoclinic, space group P21/c, a = 33.327(5) A, b = 19.145(3) A, c = 29.603(5) A, beta = 106.309(2) degrees , V = 18128(5) A3, Z = 4. In this molecule, one porphyrin ring is rotated by about 72 degrees with respect to the other in the 5-fold axis of the Cp ring.     

Synthesis,spectral, thermal,antibacterial and molecular docking studies of some metal(II) complexes of 2-(1,3-benzothiazol-2-ylamino)naphthalene-1,4-dione

Research on Chemical Intermediates - The ketoamine, 2-(1,3-benzothiazol-2-ylamino)naphthalene-1,4-dione(HL) and its Mn(II), Co(II), Ni(II), Cu(II), Pd(II) and Zn(II) complexes were synthesized and...     

Electrochemical properties of protoporphyrin IX zinc(II) films

The electrochemical properties of protoporphyrin IX zinc(II) (ZnPP) films on indium-tin oxide (ITO) substrate have been studied for three types of films with different arrangements, which were an adsorbed film of ZnPP and LB films of ZnPP and its hybrid with hexadecyltrimethylammonium bromide. Cyclic voltammetry (CV) measurement showed that, as the adsorbed amount of ZnPP increases, an irreversible oxidation peak of ZnPP film is intensified. This reveals that electrochemical properties depend on the adsorbed amount rather than the orientation of porphyrin molecules. It was also supported from CV measurement and ultraviolet-visible absorption spectroscopy that porphyrins adsorbed on ITO substrate were desorbed after the single scan of potential. Additionally, photoresponse of these ZnPP films was investigated by photocurrent measurement. The photocurrent generation is due to carboxylic acid moieties but not ZnPP macrocycles.     

ENERGY RELAXATION MECHANISM IN Ni(II), Pd(II), Pt(II) and Zn(II) PORPHYRINS

Abstract—Picosecond absorption spectroscopy was used to determine the intramolecular energy relaxation processes occurring in Ni(II). Pd(II), Pt(II), and Zn(II) protoporphyrin IX dimethyl ester. Picosecond data on the rate of ground state repopulation and the kinetics of a transient intermediate made it possible to determine the lifetimes of the excited singlet state of Ni, Pd, and Zn porphyrins as 10±2ps, 19±3ps, and 2.6±0.5 ps, respectively, and<8 ps for Pt porphyrin. On the basis of these data. the nonfluorescent and nonphosphorescent property of Ni porphyrin can be interpreted in terms of internal conversion to a lower lying singlet d-d level which is not the case for the strongly phosphorescent Pd and Pt porphyrins.     

Computational comparison of cation coordination to human prion peptide models

The coordination of the cations Cu(II), Co(II), Rh(III), Ir(III), Ni(II), Pd(II), Pt(II), and Zn(II) to the copper-binding octapeptide region in the human prion protein has been compared through structural optimization. The initial coordination mode used in the calculations is a five-coordinated mode obtained from previously published crystallographic data for Cu(II). The computational results show that, among these cations, the coordinations of Co(II) and Rh(III) are the most similar to that of Cu(II). The cations Ni(II), Pd(II), and Pt(II) prefer a four-coordinate square-planar coordination by the peptide ligand. The paramagnetic Co(II) ion with its large quadrupole moment is not a good substitute for Cu(II) to be used in NMR spectroscopic studies of the coordinated peptide region. Rh(III) has more attractive NMR spectroscopic characteristics than Cu(II) and Co(II) and may represent a suitable substitute for Cu(II) in these types of studies. Some preliminary experimental studies using NMR spectroscopic methods indicate that Rh(III) coordinates the copper-binding octapeptide region of the human prion protein, although further studies are required to determine the mode of interaction in detail.     

Synthesis and coordination chemistry of an alkyne functionalised bis(pyrazolyl)methane ligand

The alkyne functionalised bidentate N-donor ligand (2-propargyloxyphenyl)bis(pyrazolyl)methane was prepared in high yield from the reaction of (2-hydroxyphenyl)bis(pyrazolyl)methane with propargyl bromide in the presence of base. A series of transition-metal complexes including [MCl2] (M=Cu, Co, Ni, Zn, Pt), [M2](NO3)2 (M=Cu, Co, Ni, Zn), [Ag]NO3 and [Pd(dppe)](OTf)2 were prepared and characterised by spectroscopic techniques. In addition, ligand as well as the Co(II) and Zn(II) complexes [CoCl2]2, [ZnCl2] were structurally characterized by single-crystal X-ray diffraction. The organometallic gold(I) and platinum(II) acetylide complexes [Pz2CH(C6H(4)-2-OCH2C[triple bond, length as m-dash]CAuPPh3)] and trans-[{Pz2CHC6H(4)-2-OCH2C[triple bond, length as m-dash]C}2Pt(PPh3)2] were prepared from and [AuCl(PPh3)] and trans-[PtCl2(PPh3)2], respectively. Treatment of these complexes with [Pd(OTf)2(dppe)] or [Cu(MeCN)4]PF6 results in formation of the cationic, mixed-metal complexes, which were isolated (Pt/Pd, Au/Pt) or detected by electrospray mass spectrometry (Au/Cu, Pt/Cu).     

Studies on catalytic fluorescence formation with peroxidase-like metallotetrakis(N-methylpyridiniumyl) porphyrins

The relative ability of peroxidase-like metallotetrakis(N-methylpyridiniumyl)porphyrins [Me-TMPyP, Me = Mn(III), Fe(III), Co(III), Ni(II), Cu(II), and Zn(II)] to catalyse the hydrogen peroxide oxidation of homovanillic acid to a fluorescent dimer has been studied. The complexes of Mn, Fe and Co are effective catalysts in the reaction, but the complexes of Ni, Cu and Zn are not. The catalytic behaviour of Mn-TMPyP, Fe-TMPyP and Co-TMPyP has been compared with that of HRP in both enzymatic and kinetic analysis. The sequence of peroxidase-like catalytic activity is Mn-TMPyP> Co-TMPyP> Fe-TMPyP. The catalytic activity of Mn-TMPyP is 84% of that of HRP. These Me-TMPyP (Me = Mn, Fe, and Co) compounds are good substitutes for HRP in enzymatic analysis. Traces of hydrogen peroxide and glucose can be determined with the Me-TMPyP systems.     

Mesomorphic phase transitions of tetraphenylporphyrins with four long aliphatic chains

Abstract

Studies of 5,10,15,20-tetrakis(4-n-alkylphenyl)porphyrins revealed that the homologues with longer alkyl chains than hexyl were mesomorphic, in contrast to the non-mesomorphic alkoxy derivatives. Metal complexes (Co, Ni, Cu, Zn, and Pd) of the dodecyl derivative were also shown to exhibit mesophases. These mesophases were assigned as discotic lamellar (D_L) phases by X-ray diffraction studies.     

Spectroscopic and thermodynamic studies of complexation of some divalent metal ions with isatin-<Emphasis Type="Italic">β</Emphasis>-thiosemicarbazone

Metal complexes of some divalent metal ions (Co, Ni, Cu, Zn, Hg, and Pd) with isatin-β-thiosemicarbazone (ITS) as the Schiff base have been investigated potentiometrically and spectrophotometrically. The dissociation constants of the ligand and formation constants of the metal complexes, as well as the corresponding thermodynamic functions (ΔG, ΔH and ΔS) have been determined at different temperatures in ethanol—water solution. The full stability constants were also evaluated spectrophotometrically by the Job method. The experimental results indicate that Cu(II), Zn(II), Pd(II), and Hg(II) form one-to-one molecular complexes (ML) with the studied ligand, whereas Co(II) and Ni(II) form both ML and ML₂ species.     

Synthesis of Vinylene-Co,N-Linked Multi(porphyrin)s by the Addition of Free-Base Porphyrins to a C(2)H(2) Complex of Cobalt(III) Porphyrin and Their Oxidative Rearrangement to Vinylene-N,N'-Linked Multi(porphyrin)s

The nucleophilic addition reaction of a pyrrole nitrogen of free-base porphyrins to a pi-complexed acetylene ligand in a cationic Co(III) porphyrin intermediate afforded good yields of vinylene-Co,N'-linked bis(porphyrin)s, (Por)Co(III)-CH=CH-(N-Por)H(2). N-substituted porphyrin free bases are N-vinylated regioselectively at the pyrrole adjacent to the original N-substituted pyrrole in this reaction. Tris- and tetrakis(porphyrin)s have been prepared by reacting a vinylene-N,N'-linked bis(meso-tetraarylporphyrin) with (OEP)Co(III)(H(2)O)(2)ClO(4) (OEP: octaethylporphyrin dianion) and acetylene. The tetrakis(porphyrin) proved to be a 1:1 mixture of C(i)()- and C(2)-symmetric regioisomers. These organometallic Co(III) complexes underwent facile oxidative migration of the Co-bound vinyl group to a porphyrin pyrrole nitrogen when treated with Fe(III) salts or HClO(4) to provide moderate to good yields of Co(II) vinylene-N,N'-linked multi(porphyrin) complexes. (Vinylene-N,N')bis(porphyrin) free bases with combinations of different porphyrins have been obtained by this procedure. The homobinuclear (2Co(II), 2Cu(II), and 2Zn(II)) and heterobinuclear (Co(II)Cu(II) and Co(II)Zn(II)) complexes have been prepared and characterized spectroscopically. The single-crystal X-ray analysis of (CH=CH-N,N')[(OEP)Co(II)Cl][(TPP)Zn(II)Cl] (TPP: meso-tetraphenylporphyrin dianion) showed a face-to-face structure with an average inter-ring separation of 4.39 ? (triclinic P&onemacr;; Z = 2; a = 14.806(4), b = 18.703(10), c = 13.796(3) ?, alpha = 97.69(3), beta = 99.57(2), gamma = 96.74(3) degrees ).     

Reactions of Chelate Complexes with Macrocyclic Ligands. Tetra-tert-butylphthalocyanine

Complexation reactions of tetra-tert-butylphthalocyanine (I) with Cu(II) acetate, acetylacetonate, 8-hydroxyquinolate, glycinate, valinate or dithizonate, as well as with Zn(II), Co(II), and Ni(II) 8-hydroxy-quinolates, valinates, and dithizonates were studied. Unlike porphyrins themselves and porphyrins with planar distortions, compound I was found to form metal phthalocyanines with all indicated chelate salts in common solvents. It was established that compound I exhibits more equalized dependences of the coordination rate on the nature of the salt anion and cation as compared to the majority of the other porphyrins.     

Synthesis, characterization and thermal study of solid mandelate of some bivalent transition metal ions in CO2 and N2 atmospheres

Solid state M-L, where M stands for bivalent transition metals (Mn(II), Fe(II), Co(II), Ni(II), Cu(II) and Zn(II)) and L is mandelate, were synthesized. Simultaneous thermogravimetry and differential scanning calorimetry, elemental analysis and complexometry were used to establish the stoichiometry and to study the thermal behaviour of these compounds in CO₂ and N₂ atmospheres. The results show that all the compounds were obtained in the anhydrous state and in agreement with the general formula ML₂. The thermal decomposition of the compounds occurs in a single (Cu(II)), two (Ni(II)) three (Fe(II), Co(II)), four (Mn(II)) and five (Zn(II)) steps. The results also provided information concerning the ligand’s denticity, thermal behaviour, final residues and identification of gaseous products evolved during the thermal decomposition of these compounds.     

Facile synthesis and reactions of some olefin-substituted acetylacetonate complexes

Synthesis of transition metal complexes of olefin-substituted acetylacetones has been effected by reaction of nonaqueous solutions of substituted acetylacetones with the metal salt in the presence of Zn or Mg. 3-Allylacetylacetonates of Be(II), Cu(II), Ni(II), Fe(III), Co(II), Pd(II) and Zn(II) have thus been synthesized in quantitative yields. 3-Propylideneacetylacetone, which exists mainly in the keto form, afforded the corresponding 3-propenylacetylacetonates in which 3-propylideneacetylacetone has rearranged to 3-propenylacetylacetone which has a greater probability of existing in the enol form, thus making its reaction with metal ions favorable. Metal–metal exchange reactions of transition metal salts with olefin-substituted Zn or Mg acetylacetonates provide yet another route for the synthesis of transition metal olefin-substituted acetylacetonates. The homogeneous catalytic hydrogenation of the olefin moiety in olefin-substituted metal acetylacetonates could be achieved by a Pt/Sn catalyst.     

Synthesis and studies on metal coordination with a novel carboxyamide ligand

Novel complexes of Co(II), Ni(II), Cu(II) and Pd(II) with the new ligand [N,N'-bis(2-carboxy-1-oxo-phenelenyl)ethylenediamine] (H2L) have been synthesized and characterized on the basis of elemental analyses, magnetic susceptibility, thermal, infrared, electronic, 1H NMR and EPR spectral studies. Infrared and 1H NMR spectra show that H2L acts as a binegative tetradentate ligand. Coordination occurs through deprotonated carboxylate oxygens and nondeprotonated amido nitrogens in all the complexes. Electronic spectral studies and magnetic moment values suggest N2O2 coordination around each metal centre with strong field square planar chromophores. The probable structures of the complexes have been assigned on the basis of spectral studies. The complex formation between M(II) [M(II) = Mn(II), Co(II), Ni(II), Cu(II) and Zn(II)] and (L2-) has also been studied potentiometrically in 75% aqueous DMF at 25 degrees C in 0.1 M NaClO4. The stability constants were found to follow the order: Mn(II) < Co(II) < Ni(II) < Cu(II) > Zn(II).