Mixed Ligand Complexes Of Zinc Research Articles

Erratum to: Structural, thermal kinetics and thermodynamics study of new mixed ligand zinc complexes

Erratum to: Structural, thermal kinetics and thermodynamics study of new mixed ligand zinc complexes

Zinc(II) Complexes of Acetophenone and 5-Chloro-2-hydroxy-benzophenone Thiosemicarbazones. Synthesis, Characterization, and Nonlinear Optical Properties from Quantum Chemical Calculations

GRAPHICAL ABSTRACT

Synthesis, Spectral and Thermal Studies of Mixed Ligand Complexes of Cd2+, Zn2+ and Cu2+ with Succinic, Phthalic and Anthranilic Acid

Mixed ligand complexes of zinc, cadmium and copper with phthalic, succinic and anthranilic acid have been synthesized. The complexes have been characterized on the basis of analytical data, thermogravimetric studies, IR and NMR. IR spectral studies suggest that bidentate chelating behavior of succinic and phthalic and anthranilic acid in its complexes.

In situ complexation of 8-hydroxyquinoline and 4,4′-bipyridine with zinc(II) in the interlayer space of montmorillonite

A series of mixed-ligand zinc complexes was prepared by coordination of 8-hydroxyquinoline and 4,4′-bipyridine to interlayer zinc(II) ion of montmorillonite through solid–solid reactions at room temperature. The intercalation of the ligands and the in situ formation of the mixed-ligand zinc complexes in the interlayer spaces of montmorillonite were confirmed by powder XRD, TG-DTA, as well as FT-IR, UV-Vis and photoluminescence spectroscopies. The intense photoluminescence of zinc(8-hydroxyquinoline)(4,4′-bipyridine)-montmorillonite hybrids appeared at 503nm while photoluminescence of zinc(4,4′-bipyridine)(8-hydroxyquinoline)-montmorillonite hybrids was seen at 511nm. The blue- and red-shifts of the luminescent bands of the hybrids compared with that of zinc(8-hydroxyquinoline)2-montmorillonite (506nm) suggested that the different types and/or microstructure of the mixed-ligand zinc complexes formed in the interlayer spaces of montmorillonite. The photoluminescence intensities of the as-prepared mixed-ligand zinc complexes in montmorillonite decreased in the order of zinc(8-hydroxyquinoline)(4,4′-bipyridine)2-montmorillonite>zinc(8-hydroxyquinoline)(4,4′-bipyridine)-montmorillonite>zinc(4,4′-bipyridine)(8-hydroxyquinoline)2-montmorillonite>zinc(4,4′-bipyridine)(8-hydroxyquinoline)-montmorillonite>zinc(8-hydroxyquinoline)-montmorillonite. The sequence of ligand loading affected the molecular structure and/or packing of the formed complex to control the photoluminescence efficiencies of the hybrids.

Synthesis, crystal structure, spectroscopic and biological properties of mixed ligand complexes of zinc(II) valproate with 1,10-phenanthroline and 2-aminomethylpyridine

Mononuclear zinc(II) complexes with mixed ligands formulating [Zn(valp)2(1,10-phen)H2O] (2), and [Zn(valp)(2-picam)2](valp) (3) (valp=valproate, phen=1,10-phenanthroline, 2-picam=2-aminomethylpyridine (2-picolylamine)) have been synthesized and characterized using IR, 1H NMR, 13C{1H} NMR and UV–Vis spectroscopic techniques, as well as single-crystal X-ray diffraction. Zn(II) cation in 2 exhibits a distorted octahedral environment resulting from one bidentate phen ligand, one valproate ligand with asymmetric chelating mode, and another one with monodentate mode and a molecule of water. Complex 3 has two bidentate 2-ampic ligands and two valproate ligands. Only one of the carboxylate ligands was bonded to Zn(II) in a monodentate mode. The second valproate ligand acted as a counter ion and was bonded to the NH2 groups of 2-picam through hydrogen bonding. The Zn(II) cation in 3 has a distorted trigonal bipyramidal arrangement. The complexes were also evaluated for their anti-bacterial activity using in vitro agar diffusion method. Three Gram-positive (Micrococcus luteus, Staphylococcus aureus, and Bacillus subtilis) and three Gram-negative (Escherichia coli, Klebsiella pneumoniae, and Proteus mirabilis) species of bacteria were used for testing anti-bacterial activities. Complex 2 showed considerable activity against all tested microorganisms. The effect of complexation on the anti-bacterial activity of the parent ligand of 2 was also investigated. The anti-bacterial activity of 1,10-phen against both Gram-positive and Gram-negative bacteria was reduced upon complexation with zinc valproate. Complex 3 showed weak inhibition activity against S. aureus, B. subtilis, E. coli and K. pneumoniae.

Synthesis, Characterization, and Electroluminescent Characteristics of Mixed-Ligand Zinc(II) Complexes

Mixed-ligand zinc complexes, i.e., 2-(2-hydroxyphenyl)benzothiazolato-5,7- dichloro-8-hydroxyquinolinato zinc(II) [ZnBTZ(Cl2q)], 2-(2-hydroxyphenyl) benzothiazolato-5,7-dimethyl-8-hydroxyquinolinato zinc(II) [ZnBTZ(Me2q)], and 2-(2-hydroxyphenyl)benzothiazolato-2-carbonitril-8-hydroxyquinolinato zinc(II) [ZnBTZ(CNq)], were synthesized and characterized. The metal complexes have high thermal stability (>300°C) and high glass-transition temperature (>150°C) and are suitable for optoelectronic applications. Optical properties of the synthesized complexes were characterized by using ultraviolet–visible (UV–Vis) and photoluminescence spectroscopy. Color tuning by changing the ligand was observed in synthesized complexes. Multilayered organic electroluminescent devices were fabricated having structure indium–tin oxide (ITO)/N,N′-diphenyl-N,N′-bis(1-naphthyl)-1,1′-biphenyl-4,4′-diamine (α-NPD)/zinc complex/2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP)/tris(quinolinolate)AlIII (Alq3)/LiF/Al using the synthesized complexes as emissive material. The electroluminescence spectra show peak emission centered at 532 nm, 572 nm, and 541 nm, respectively, for these materials. The emitted light has chromaticity with Commission Internationale d’Eclairage coordinates x = 0.35 and y = 0.56 for ZnBTZ(Cl2q), x = 0.49 and y = 0.47 for ZnBTZ(Me2q), and x = 0.48 and y = 0.40 for ZnBTZ(CNq) complex.

Equilibrium Studies of Binary and Mixed-Ligand Complexes of Zinc(II) Involving 2-(Aminomethyl)-Benzimidazole and Some Bio-Relevant Ligands

Binary and mixed-ligand complexes of zinc(II) involving 2-(aminomethyl)-benzimidazole (AMBI) and amino acids, peptides (HL) or DNA constituents have been investigated. Ternary complexes of amino acids or peptides are formed simultaneously. Amino acids form the complex Zn(AMBI)L, whereas amides form two complex species Zn(AMBI)L and Zn(AMBI)(LH−1). The ternary complexes of zinc(II) with AMBI and DNA are formed in a stepwise process, whereby binding of zinc(II) to AMBI is followed by ligation of the DNA constituents. The stability of ternary complexes is quantitatively compared with their corresponding binary complexes in terms of the parameters Δlog10 K, log10 βstat and log10 X. The effect of the side chains of amino acid ligands (ΔR) on complex formation is discussed. The values of Δlog10 K indicated that the ternary complexes containing aromatic amino acids are significantly more stable than the complexes containing alkyl- and hydroxyalkyl-substituted amino acids. This may be taken as evidence for a stacking interaction between the aromatic moiety of AMBI and the aromatic side chains of the bio-active ligands. The concentration distributions of various species formed in solution were also evaluated as a function of the pH.

Mixed-ligand complexes of zinc(II), cobalt(II) and cadmium(II) with sulfur, nitrogen and oxygen ligands. Analysis of the solid state structure and solution behavior. Implications for metal ion substitution in alcohol dehydrogenase

In this paper we characterize new, mixed ligand complexes of zinc(II), cobalt(II) and cadmium(II) with tri- tert-butoxysilanethiolate and 2-(2′-hydroxyethyl)pyridine ligands. Due to the chelating versus non-chelating behavior of 2-(2′-hydroxyethyl)pyridine ligand we have obtained an interesting structural variety in the studied system. The presented coordination patterns together with the results of NMR studies have been used to illustrate a rapid chemical exchange undergoing in methanolic solutions of zinc(II) and cadmium(II) complexes. UV–Vis spectra of cobalt(II) species have also evidenced an exchange in the case of cobalt(II) complex. The relative strength of hydrogen bond formed by hydroxyl group bonded to Zn(II), Co(II) or Cd(II) was evaluated by analysis of structural parameters and position of the OH stretching vibrations in the FT-IR spectra of the complexes in solid state. The data were compared with the activity of zinc (native) alcohol dehydrogenase and alcohol dehydrogenase substituted with cobalt and cadmium ions. The enthalpies of proton abstraction in zinc and cobalt complexes were calculated and found to be very similar. The attempt to apply zinc tri- tert-butoxysilanethiolate as a catalyst in the biomimetic reaction of reduction of N-benzylnicotinamide chloride by ethanol was unsuccessful.

Synthesis and characterization of mixed ligand complexes of zinc and cadmium ions with some nitrogen and sulphur donors

Synthesis and characterization of mixed ligand complexes of zinc and cadmium ions with some nitrogen and sulphur donors

Synthesis and characterization of mixed ligand complexes of zinc and cadmium ions with some nitrogen and sulphur donors

Mixed ligand complexes of zinc and cadmium ions with sulphur ligand, 1,1-dicyanoethylene-2,2-dithiolate [i-AINT 2- = {S 2 C : C(CN) 2 } 2- ] as a primary ligand and nitrogen donor, o-phenylenediamine (OPD), as secondary ligand of the composition M(OPD)(i-MNT) [M = Zn or Cd] have been synthesized. Reactions of M(OPD)(i-MNT) with pyridine bases such as pyridine (py), α-picoline (a-pic), β-picoline (β-pic) or γ-picoline (y-pic) have been carried out under different reaction conditions. Some of the reactions have yielded addition compounds whereas others have resulted the compounds in which OPD has been replaced by pyridine bases. The complexes have been characterized on the basis of analytical data, molar conductance, infrared and NMR spectral studies. The molar conductance data reveal that all of the complexes have non-electrolytic nature in DMF solution. Infrared spectral studies suggest bidentate chelating behaviour of i-MNT 2- ion and OPD while other ligands show unidentate behaviour in its complexes.

Synthesis, spectral characterization of the zinc(II) mixed-ligand complexes of N(4)-allyl thiosemicarbazones and N, N, N′, N′-tetramethylethylenediamine, and crystal structure of the novel [ZnL 2( tmen)] compound

Mixed-ligand zinc complexes with N, N, N′, N′-tetramethylethylenediamine ( tmen) and R-salicylaldehyde N(4)-allyl thiosemicarbazones (R: 3-OCH 3 (L 1), 5-Br(L 2)), [ZnL 1,2( tmen)], were synthesized and the complexes were characterized by elemental analysis, atomic absorption spectrometer, magnetic susceptibility, molar conductivity, electrospray ionization (ESI) and atmospheric pressure chemical ionization (APCI) mass spectra and IR, UV–Vis, 1H NMR and 15N spectroscopies. Crystal of [ZnL 2( tmen)] have a slightly distorted square pyramid involving O, N, S atoms of thiosemicarbazone and one N atom of tmen in basal plane and the other N atom of tmen in apex of the pyramid. The non-coordinated allyl group is disordered.

Syntheses and crystal structures of two mixed-ligand dimeric zinc complexes containing a dithiol ligand and an open chain crown ether ligand with terminal quinolyl groups

Two mixed-ligand zinc complexes Zn(L)(H 2O)(mnt) ( 1) and Zn(L)(H 2O)(i-mnt) ( 2) (where L=2,6-bis(8′-quinoylyloxymethyl)pyridine, mnt =1,2-dicyanoethylene-1,2-ditholate and i-mnt =1,1-dicyanoethylene-2,2-ditholate) have been synthesized and characterized by elemental analysis, FT-IR spectra, and single-crystal X-ray diffraction. Complexes 1 and 2 both crystallize in the monoclinic system, space group C2/ c and each displays a distorted trigonal bipyramidal around zinc atom. The coordination sphere of Zn is NO 2S 2 type, where the dithiol ligand (mnt or i-mnt) and one terminal quinolyl group of L act as the chelate S, S and N, O donor sets, respectively, besides the coordination water molecules. Furthermore, there are intramolecular H-bonds occurred between the coordination water molecule and the N2, N3 atoms of the L and the molecules of 1 and 2 both form the dimers through the intermolecular π–π stacking interactions.

Crystal structure of the complex Zn(2,2′-Bipy)(C2H5OCS2)2 with mono- and bidentate ethylxanthate ligands

While seeking molecular precursors for ZnS films obtained by gas phase chemical deposition [1, 2] we synthesized mixed-ligand compounds ZnL(ROCS2)2 [R = i-Pr. /-Bu; L = 2,2′-bipyridyl (2,2′-Bipy), 1,10-phenanthroline (Phen)] [3]. The volatile complex Zn(2,2′-Bipy)(i-PrOCS2)2 was used as a precursor to obtain electroluminescent ZnS:Mn films [4]. According to XRD data, the compound Zn(Phen)(i-BuOCS2)2 is monomeric. The c.n. of zinc is six. The Phen and 1-B11OCS2 ions behave as cyclic bidentate ligands [3, 5]. It was assumed that other mixed-ligand complexes with Phen and 2,2′-Bipy have an analogous structure [3]. Here we report on the structure of the known mixed-ligand complex of zinc(II) ethylxanthate with 2,2′-bipyridyl [6, 7]. It was found that the behavior of alkylxanthate ligands in mixed-ligand complexes of zinc(II) is more complex.

Thin-layer chromatography of mixed-ligand zinc complexes coupled with atomic absorption spectrometric analysis of zinc

Off-line coupling of two analytical methods: thin-layer chromatography (TLC) and atomic absorption spectrometry (AAS) was investigated for preliminary stability studies of zinc carboxylato complexes bound to nicotinic acid and their chromatographic separation on a Silufol layer. Zinc content, determined by an AAS method in fractions scrapped off the layers after zinc carboxylato complex (ZC) chromatographic analyses responds to ZC dissociation during chromatographic process. It was found that solute chromatographic stability is influenced substantially by the concentration of organic modifier in the eluent. To reveal relations between zinc distribution, corresponding solute retention and complex stability was the main aim of the presented paper.

Synthesis and characterization of mixed ligand complexes of zinc (II) with uridine and amino acids

Mixed ligand complexes of zinc(II) with uridine and aminoacidsL-alanine,L-phenylalanine and L-tryptophan were synthesized and characterized by elemental analysis, conductivity data, electronic, IR,1H-NMR and13C-NMR spectra. In these complexes, the nucleoside (uridine) acts as a monodentate ligand coordinating through O(4) under conditions of investigation whereas the aminoacids coordinate through carboxylate oxygen and amino nitrogen. The results drawn about binding sites of these octahedral complexes are compared with the results obtained from solution studies for a comprehensive understanding of the binding sites in these systems.

Synthesis and characterization of mixed ligand complexes of zinc(II) with cytidine and amino acids

Synthesis and characterization of mixed ligand complexes of zinc(II) with cytidine and amino acids

The photochemistry of mixed-ligand complexes (ArS)2ZnPhen with the lowest ligand—ligand charge transfer excited states

Abstract Flash photolysis and spin-trapping experiments were performed to investigate the photochemistry of the mixed-ligand zinc complexes (4—XC 6 H 4 S) 2 Zn(Phen) (XH, MeO or Me 2 N) in liquid solutions. The lowest ligand—ligand charge transfer excited state of these complexes was shown to dissociate, yielding arylthiyl radicals and a reduced zinc-phenanthroline moiety. Back electron transfer with nearly diffusion-controlled rates was found to be a predominant process in the case of MeO- and Me 2 N-substituted arylthiolate complexes while the recombination of unsubstituted phenylthiyl radicals is also significant. The reductive dissociation product may be trapped by oxygen or methyl viologen (MV 2+ ) cations, leading to the photo-oxidation of complexes in aerated solutions or production of MV + radical cations. The latter decays via diffusion-controlled electron transfer to arylthiyl radicals. Steady state illumination produces MV + only in solutions of phenylthiolate complex where its oxidation by phenylthiyl radicals competes with recombination of the latter.

Mixed-ligand complexes of zinc(II) and cadmium(II) diethyldithiocarbamates with 2,2?-bipyridyl and 4,4?-bipyridyl: Synthesis, structure, and thermal properties

We have synthesized novel mired-ligand complexes of zinc(I1) and cadmium(ZI) diethyldithiocarbamates ZnL2(2,2'-Bipy) (1), Zn2L4(4,4'-Bipy) (2), and CdL2(4,4'-Bipy) (3), where L = (C2H5NCS2−. An X-ray structural study of zinc compleres 1 and 2 has been cam'ed out. The saucture of complex 1 is characterized by monomeric molecules of symmeby 2. In the crystal structure of complex 2, there are fwo independent binuclear molecules of the same point symmetry 2. It is shown that not only the mononuclear mixed-ligand complaes ML2 with Phen and 2,2'-Bipy (M = Zn, Cd) but also the binuclear Zn2L4(4,4'-Bipy) complex are volatile.

Spectroscopic and magnetic studies of mixed-ligand complexes of zinc (II)

Zero-field splittings and the kinetic parameters associated with the triplet spin sublevels of both the triplet ππ* and the triplet ligand-ligand charge-transfer states were measured by the optically-detected magnetic-resonance method for a series of complexes with a d10 closed-shell metal ion of the type, Zn(X-PhS)2(phen), where X = F5, 4-C1, H, 4-CH3, or 4-CH3O. Both the zero-field splittings and the kinetic decay parameters are satisfactorily interpreted in terms of mixing between the lowest phen-localized3ππ* and ligand-ligand charge-transfer states.

Spectral and thermal studies on mixed lignad complexes of zinc(II) and cadmium (II) with diethyldithiocarbamate and 2,2′-bipyridyl/1,10-phenanthroline

Mixed ligand complexes of zinc(II) and cadmium(II) with diethyldithiocarbamate (ddtc) as a primary ligand and pyridine (py), 4-picoline (4-pic), 2,2′-bipyridyl (bpy), 1,10-phenanthroline (phen) as secondary ligands have been prepared and characterized by elemental analysis, thermogravimetric (TG) studies, infrared and1H-NMR spectral data. The general formula of cadmium(II) complexes are (L)2 Cd(ddtc)2 and (L-L)Cd(ddtc)2 while corresponding zinc complexes have (L)Zn(ddtc)2 and (L-L)Zn(ddtc)2 (where, L=py, 4-pic; L-L=bpy, phen) as evidenced by their elemental analysis and thermogravimetric studies. Infrared spectral data reveal that ddtc acts as a bidentate ligand in all cadmium complexes. However, in (L)Zn(ddtc)2 and (L-L)Zn(ddtc)2 complexes ddtc acts as bi-and unidentate ligand respectively. Octahedral geometry is assigned for all cadmium(II) complexes. Although (py)Zn(ddtc)2 and (4-pic)Zn(ddtc)2 complexes are known to have pentacoordinate zinc, yet the other mixed ligand complexes of Zn(ddtc)2 with bpy and phen have tetracoordinate zinc as evidenced by their infrared spectra. High resolution (300 MHz)1H-NMR spectra support the characterization of all complexes. TG data indicate that cadmium complexes initiate decomposition at high temperature in comparison with their respective zinc complexes. Thermograms of all mixed ligand complexes have two decomposition regions, out of which the first one corresponds to the removal of secondary ligands.