Hydrothermal syntheses,crystal structures and luminescence properties of two lanthanide dinuclear complexes with hexafluoroglutarate

Two complexes [Ln₂(hfga)₂(phen)₄(H₂O)₆] · hfga · 2H₂O (H₂hfga = hexafluoroglutaric acid, phen = 1, 10-phenanthroline, Ln=Tb, 1; Eu, 2) were synthesized under hydrothermal conditions and their structures determined by X-ray crystallography. The complexes consist of dinuclear units with an inversion center. Each Ln(III) is nine-coordinate with two carboxylate oxygens from two hfga ligands, three oxygens from water and four nitrogens from two phen molecules. Two carboxylate groups of one hfga adopt monodentate coordination to Ln(III) as a long bidentate bridge linking two Ln(III) ions to form a dimer. Ln(III) ··· Ln(III) distances of 9.027(3) Å for 1 and 9.043(3) Å for 2 were observed. Both complexes emit strong fluorescence and show characteristic emission of Tb(III) and Eu(III) ions, respectively.     

Synthesis of cationic gold(III) complexes using iodine(III)

Abstract

We report the synthesis and characterization of cationic Au(III) complexes supported by nitrogen-based ligands. The syntheses are achieved by reacting Au(I) complexes [Au(N-Me-imidazole)₂]⁺ and [Au(pyridine)(NHC)]⁺ with iodine(III) reagents PhI(OTf)(OAc) and [PhI(pyridine)₂]²⁺ yielding a series of cationic gold(III) complexes. In contrast, reactions of phosphine ligated gold(I) complexes with iodine(III) reagents results in the oxidation of the phosphine ligand.     

Synthesis,Characterization, Antimicrobial Activities,and Structural Studies of Lanthanide (III) Complexes with 1-(4-Chlorophenyl)-3-(4-fluoro/hydroxyphenyl)prop-2-en-1-thiosemicarbazone

Twelve coordinate lanthanide (III) complexes with the general composition [Ln L₃X_n(H₂O)_n] where Ln = Pr(III), Sm(III), Eu (III), Gd (III), Tb (III), Dy (III), X = Cl^?1, NO₃ ^?2, n = 2–7, and L is 1-(4-chlorophenyl)-3-(4-fluoro/hydroxyphenyl)prop-2-en-1- thiosemicarbazone have been prepared. The lanthanide complexes (5) were derived from the reaction between 1-(4-chlorophenyl)-3-(4-fluoro/hydroxyphenyl)prop-2-en-1-thiosemicarbazone (4) with an aqueous solution of lanthanide salt. Chalcone thiosemicarbazone ligand (4) was prepared by the reaction of [1-(4-chlorophenyl)-3-(4-fluoro/hydroxyphenyl)]prop-2-enone (chalcone) (3) with thiosemicarbazide in the presence of hot ethanol. All the lanthanide-ligand 1:3 complexes have been isolated in the solid state, are stable in air, and characterized on the basis of their elemental and spectral data.

Thiosemicarbazone ligands behave as bidentate ligands by coordinating through the sulfur of the isocyanide group and nitrogen of the cyanide residue. The probable structure for all the lanthanide complexes is also proposed. The chalcone thiosemicarbazone ligands and their lanthanide complexes have been screened for their antifungal and antibacterial studies. Some of the synthesized lanthanide complexes have shown enhanced activity compared with that of the free ligand.

Supplemental materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements to view the free supplemental file.     

Thin-Layer Chromatography of Metal Ions Complexed with Anils (V). Detection,Separation and Determination

Abstract

p-Diethylaminoanil of phenylglyoxal a bidentate ligand was used for complexation with Hg(II), UO₂(II), Au(III), Pt(IV) Mg(II), Bi(III), Sb(III) and Be(II) ions. The chelates were characterized by their analysis, molar conductance and infrared spectra. T.L.C. detection, separation and determination of these complexes on starch bound silica gel layers was studied Long persisting dark coloure of the complexes rendered the spots self descernible and no locating agent was required. A maximum four complexes could be resolved and identified. Errors in determinations and maximum separation limits were also deduced.     

Synthesis,crystal structure,and antimicrobial activity of a series of cobalt(III) Schiff base complexes

Abstract

A series of six new mononuclear Schiff base complexes, 1–6 of cobalt(III) of the general formula, [CoLX] or its adduct with methanol, is reported. The pentadentate Schiff base ligand (H₂L) was obtained by the condensation of N-(3-aminopropyl)-N-methylpropane-1,3-diamine with 1-(2-hydroxyphenyl)ethanone (H₂L¹) or 1-(2-hydroxyphenyl)propan-1-one (H₂L²). X stands for the pseudohalides, N₃^–, N(CN)₂^? , and NCS^–. The complexes have been synthesized by the reaction of equimolar amounts of cobalt(II) nitrate with H₂L¹ or H₂L² in the presence of the respective pseudohalide in methanol medium. All the complexes have been characterized by microanalytical, spectroscopic, single crystal XRD (except 3), and other physicochemical studies. Structural studies reveal that the central Co(III) ion in 1, 2, 4, 5, and 6 adopts a distorted octahedral geometry with a CoN₄O₂ chromophore. Weak intermolecular H-bonding and/or π-interactions are operative in these complexes to bind the molecular units. The antimicrobial activity of all the complexes and their constituent Schiff bases has been tested against some common bacteria and fungi.     

Synthesis, structural characterization and antimicrobial activity evaluation of metal complexes of sparfloxacin

The synthesis and characterization of binary Cu(II)- (1), Co(II)- (2), Ni(II)- (3), Mn(II)- (4), Cr(III)- (5), Fe(III)- (6), La(III)- (7), UO₂(VI)- (8) complexes with sparfloxacin (HL₁) and ternary Cu(II)- (9), Co(II)- (10), Ni(II)- (11), Mn(II)- (12), Cr(III)- (13), Fe(III)- (14), La(III)- (15), UO₂(VI)- (16) complexes with sparfloxacin (HL₁) and dl-alanine (H₂L₂) complexes are reported using elemental analysis, molar conductance, magnetic susceptibility, IR, UV–Vis, thermal analysis and ¹H-NMR spectral studies.The molar conductance measurements of all the complexes in DMF solution correspond to non-electrolytic nature.All complexes were of the high-spin type and found to have six-coordinate octahedral geometry except the Cu(II) complexes which were four coordinate, square planar and U- and La-atoms in the uranyl and lanthanide have a pentagonal bipyramidal coordination sphere. The antimicrobial activity of these complexes has been screened against two Gram-positive and two Gram-negative bacteria. Antifungal activity against two different fungi has been evaluated and compared with reference drug sparfloxacin. All the binary and ternary complexes showed remarkable potential antimicrobial activity higher than the recommended standard agents. Ni(II)- and Mn(II) complexes exhibited higher potency as compared to the parent drug against Gram-negative bacteria.     

Strongly photoluminescent Eu(III) tetrazolate ternary complexes with phosphine oxides as powerful sensitizers

The Eu(III) cation forms electrically neutral photoluminescent complex with 5-(2-pyridyl-1-oxide)tetrazolate (PTO) anion. Although the photoluminescence properties of such tertiary Eu(III) and Tb(III) complexes were not as high (13 and 31% photoluminescence quantum yield, respectively) as reported for other diketonate lanthanide complexes probably because of high number of nitrogen atoms involved in PTO which leads to attachment of water molecules, reducing the luminescence quantum yield with vibrational and rotational quenching. Here, we report the removal of quencher molecules from the coordination sphere of tris–europium tetrazolate oxide complex by replacing them with various phosphine oxides which leads to improved photoluminescence quantum yield for the complexes by acting as auxiliary co-ligands with that of the main antenna 5-(2-pyridyl-1-oxide)tetrazolate. The coordination sphere in these complexes can be complemented by aromatic phosphine oxides to provide highly photoluminescent Eu(III) complexes. The highest quantum yield was 38% in 3 [Eu(PTO)₃·DPEPO](H₂O)₅ containing bis(2-(diphenylphosphino)phenyl) ether oxide (DPEPO) as compared to tris–europium complex with 5-(2-pyridyl-1-oxide)tetrazolate.     

Synthesis,structures and properties of cobalt(III) and iron(III) complexes with a new triazamacrocycle, 1,4-diacetate-1,4,7-triazacyclodecane

A new bidisplaced acetate functionalized pendant arm derivative, 1,4-diacetate-1,4,7-triazacyclodecane (L) and its corresponding Co(III), Fe(III) complexes [CoLCl] (1) and [FeLCl]₂ · 3H₂O (2) were synthesized and characterized by elemental analysis, IR spectra,UV–Vis spectra, HNMR, MS, XPRD, TGA and single-crystal X-ray diffraction analysis. The crystal structure shows the metal ions in the complexes have similar coordination six-coordinate, by three nitrogens and two oxygens of the chelate ligand, and a chloride. Through calculation of the twist angle, we discover 1 forms a distorted octahedral geometry while 2 forms a distorted-prismatic geometry. In 2, there are abundant hydrogen bonds between the oxygen atoms of water and the nitrogens and oxygens of the ligand, resulting in a two-dimensional supramolecular network with a regular triatomic water cluster. The thermal gravimetric analyses of the two complexes are also given.     

Synthesis and Characterization of S-Triazine Cored Tripodal Keto-oxime and Its Trinuclear Complexes

2,4,6-Tris(4-hydroxybenzimino)-1,3,5-triazine (II) has been synthesized by the reaction of 1 equiv. melamine (I) and 3 equiv. 4-hydroxybenzaldehyde and characterized by means of elemental analysis, ¹H NMR, Fourier transform–infrared spectroscopy, and liquid chromatography–mass spectrometry (LC-MS). 2,4,6-tris(4-(2-phenyl-2-keto-hydroxyiminoyloxy)benzimino)-1,3,5-triazine L (III) has been synthesized by the reaction of 1 equiv. II and 3 equiv. chloroisonitrozoacetophenone and characterized by means of the same methods. Four novel trinuclear Fe(III) and Cr(III) complexes involving tetradentate Schiff bases N,N′-bis(salicylidene)ethylenediamine-(salenH₂) or bis(salicylidene)-o-phenylenediamine-(salophen H₂) with L (III) have been synthesized and characterized by means of elemental analysis, Fourier transform–infrared spectroscopy, LC-MS (ESI⁺), and thermal analyses. The metal ratios of the prepared complexes have been determined using atomic absorption spectroscopy. The aim of the present study is to synthesize novel tridirectional-trinuclear systems and to present their effects on magnetic behavior of [salen or salophenFe(III)/Cr(III)] capped complexes. The complexes have also been characterized as low-spin distorted octahedral Fe(III) and as distorted octahedral Cr(III) bridged by keton-oxime group.     

Synthesis and characterization of a new vic -dioxime 6,7- bis (hydroxyimino)-9,10-diethylidine-5,8,9,10,11,18-hexahydro-5,8,11,18-tetraazadibenzo[a,e]cyclotetradecane-6,7,12,17-tetraone and its nickel and cobalt complexes

A new vic-dioxime 6,7-bis(hydroxyimino)-9,10-diethylidine-5,8,9,10,11,18-hexahydro-5,8,11,18-tetraazadibenzo[a,e]cyclotetradecane-6,7,12,17-tetraone (H₂L) and its hydrogen-bridged tetra- and six-coordinate complexes with Ni(II), Co(II), and Co(III) have been synthesized. The six-coordinate complexes of H₂L have pyridine and chloride as axial ligands. Hydrogen-bridge complexes were converted to their BF₂-bridged analogues by reaction with boron trifluoride etherate. Structures of the H₂L and its complexes were proposed from elemental analysis, ¹H and ¹³C NMR, IR and mass spectra.     

Complexation between nickel(II), cobalt(III) and hydrazones derived from pyridoxal 5′-phosphate and hydrazides of 2-,3-,4-pyridinecarboxylic acids in aqueous solution

abstract

The present work reports on stoichiometry, apparent stability constants of biologically relevant complexes of nickel(II), cobalt(III) with hydrazones derived from pyridoxal 5′-phosphate and hydrazides of 2-,3-,4-pyridinecarboxylic acids at pH 7.4, T?=?25.0?°C, I?=?0.25 determined using UV-Vis spectroscopy. The thermodynamic constants of some complexes formation (NiL, NiL₂, NiL₂H) were estimated. Cobalt(II) ion was found to be oxidized to cobalt(III). Co(II) and Co(III) form low-spin state complexes. Hydrazones binding ability (pL_0.5) in the medium mimicking biological ones towards Ni(II) and Co(III) was estimated.     

Synthesis,Spectroscopic and Magnetic Studies on Metal Complexes of 5-Methyl-3-(2-Hydroxyphenyl)Pyrazole

A tridentate ONN donor ligand, 5-methyl-3-(2-hydroxyphenyl)pyrazole; H₂L, was synthesized by reaction of 2-(3-ketobutanoyl)phenol with hydrazine hydrate. The ligand was characterized by IR, ¹H NMR and mass spectra. ¹H NMR spectra indicated the presence of the phenolic OH group and the imine NH group of the heterocyclic moiety. Different types of mononuclear metal complexes of the following formulae [(HL)₂M][sdot]xH₂O (M=VO, Co, Ni, Cu, Zn and Cd), [(HL)₂M(H₂O)₂] (M=Mn and UO₂) and [(HL)LFe(H₂O)₂] were obtained. The Fe(III) complex, [(HL)LFe(H₂O)₂] undergoes solvatochromism. Elemental analyses, IR, electronic and ESR spectra as well as thermal, conductivity and magnetic susceptibility measurements were used to elucidate the structures of the newly prepared metal complexes. A square-pyramidal geometry is suggested for the VO(IV) complex, square-planar for the Cu(II), Co(II) and Ni(II) complexes, octahedral for the Fe(III) and Mn(II) complexes and tetrahedral for the Zn(II) and Cd(II) complexes, while the UO₂(VI) complex is eight-coordinate. Transmetallation of the UO₂(VI) ion in its mononuclear complex by Fe(III), Ni(II) or Cu(II) ions occurred and mononuclear Fe(III), Ni(II) and Cu(II) complexes were obtained. IR spectra of the products did not have the characteristic UO₂ absorption band and the electronic spectra showed absorption bands similar to those obtained for the corresponding mononuclear complexes. Also, transmetallation of the Ni(II) ion in its mononuclear complex by Fe(III) has occurred. The antifungal activity of the ligand and the mononuclear complexes were investigated.     

Synthesis,spectroscopic (IR,electronic, FAB-mass,and PXRD), magnetic,and antimicrobial studies of new iron(III) complexes containing Schiff bases and substituted benzoxazole ligands

Mixed ligand complexes of iron(III), [Fe(sb)₂(py)Cl]?·?2H₂O (1–9) [where sbH?=?Schiff bases (derived from condensation of 2-aminopyridine (sapH), 2-aminophenol (saphH), o-toluidine (o-smabH), aminobenzene (sabH), p-toluidine (p-smabH), 3-nitroaniline (snabH), and anthranilic acid (saaH) with salicylaldehyde and substituted (mercapto-)benzimidazole (mbzH), {2-(o-hydroxyphenyl)}benzoxazole, (pboxH)], have been synthesized by the interactions of iron(III) chloride with corresponding ligands in 1?:?2 molar ratio in refluxing pyridine. These complexes have been characterized by elemental analyses, melting points, spectral, and magnetic studies. Powder X-ray diffraction studies of some representative complexes are also reported herein. The antibacterial and antifungal activities of the free ligands and their iron(III) complexes were found in vitro. The complexes showed good antibacterial and antifungal effect to some bacteria and fungi. Two standard antibiotics (chloromphenicol and terbinafine) were used for comparison with these complexes.     

Organophosphorus Ligands in Studies of Metal Complexes. Investigations of Ligand Exchange and Multielement Trace Analysis using Dithiophosphinic Ligands

Abstract

On mixing organic solutions of [Et₂PS₂]M/n and [Prop₂PS₂]M/n [M=Pd(II), Pt(II), Rh(III), lr(III), Cr(III)] an equilibrium is obtained containing statistical amounts of the corresponding mixed ligand complexes as can be shown by 31P{¹H}-NMR, HPLC and FD-MS. With Pt(II)- and Pd(II)-chelates the kinetics of ligand exchange was determined by HPLC. Mixed complexes ML₂L′ and MLL′₂ were isolated from the equilibrium solutions in case of the more inert Cr(III)-, Rh(III)- and lr(III)-chelates by preparative HPLC. Pd(II), Pt(II) and Rh(III) can be determined quickly and simultaneously in aqueous solutions at nanogramm level by complexation with Et₂PS₂? in a modified sample loop followed by reversed phase HPLC.     

Synthesis,characterization, and DNA-binding of Ln(III) complexes with 2-hydroxybenzylidene-2-phenylquinoline-4-carbonylhydrazone

2-Hydroxybenzylidene-2-phenylquinoline-4-carbonylhydrazone (H₂L) and five Ln(III) complexes, [Ln(H₂L)(NO₃)₂]NO₃ [Ln = La (1), Pr (2), Sm (3), Eu (4), and Tb (5)], have been synthesized and characterized by ¹H NMR, elemental analysis, conductivity measurements, mass spectra, IR spectra, and UV spectra. The interaction of these complexes with calf thymus DNA was investigated by UV absorption spectroscopy, fluorescence spectroscopy, circular dichroism spectroscopy and viscosity measurements. Results suggest that these complexes bind to DNA via groove binding.     

Synthesis,crystal structure,and luminescence properties of [TbGd(NAA)6(phen)2] and [Tb2(NNA)6(phen)2] · 2C3H7NO

Lanthanide(III) heteronuclear and binuclear complexes [TbGd(NAA)₆(phen)₂] (1) and [Tb₂(NAA)₆(phen)₂] · 2C₃H₇NO (2) (NAA = 1-naphthylacetic acid, phen = 1,10-phenanthroline) were prepared and their crystal structures were determined. In 1 and 2, each lanthanide is nine-coordinate by two bidentate-bridging and two tridentate chelating-bridging carboxylate groups, one bidentate chelating carboxylate and one phen molecule in a distorted monocapped square antiprism. The solid-state luminescence behavior and the antibacterial activities were studied. Complexes 1 and 2 exhibited characteristic emission of Tb(III) ion ⁵D₄ → ⁷F_J (J = 6–0) under UV radiation at room temperature. A main excitation peak (359 nm) of 2 appears under red emission of 615 nm. By contrast, all emission peak intensities of 1 were enhanced by addition of gadolinium(III), and the 545 nm band is much stronger than the 615 nm band, attributed to, under perturbation of the ligand field, the probability of ⁵D₄ → ⁷F₃ transition of Tb(III) was greatly enhanced in 2. Because of perturbation of the ligand field by addition of gadolinium(III), the probability of ⁵D₄ → ⁷F₅ transition of Tb(III) was greatly enhanced in 1 and green fluorescence was observed. The antibacterial activity showed that the two complexes were active against Escherichia coli, Staphylococcus aureus and Bacillus subtilis.     

Dirhenium(III,III) trithiocarbamato complexes: experimental and theoretical investigation

The green colored trithiocarbamato complexes of dirhenium(III,III) of type [Re₂(μ-η²-SL_R)₂(η²-L_R)₃][ReO₄] (4(L_R)), where L_R represents the dithiocarbamato ligands [L_R?=?S₂CNEt₂, 4(L_Et) and S₂CN(CH₂)₄, 4(L_Pyr)], have been synthesized in moderate yield by reacting Re₂(μ-O₂CCH₃)₄Cl₂ (1) and sodium salt of diethyldithiocarbamate or pyrrolidinedithiocarbamate in boiling ethanol under nitrogen atmosphere. The spectral (IR, UV–vis, NMR) and electrochemical properties of the complexes are reported. The identity of complex 4(L_Et) has been established by single-crystal X-ray structure determination. The density functional theory (DFT) calculations rationalized the electronic structure of complexes 4(L_R) in comparison with dithiocarbamato complexes of dirhenium(II,II) and dirhenium(III,II). The absorption spectra of the 4(L_R) complexes are scrutinized by the time-dependent DFT analysis.

     

Emissive mononuclear Eu(III) and Tb(III) complexes bearing deprotonated 2,2′-bipyridyl-1,2,4-triazole terdentate ligands

A series of new emissive mononuclear Ln(III) complexes with deprotonated 2,2?-bipyridyl-1,2,4-triazole terdentate ligands, [Ln(L)(DMF)₂(NO₃)₂]?n(solvent) (Ln = Eu (1 and 2), Tb (3 and 4), HL = 6-(5-trifluoromethyl-1,2,4-triazol-3-yl)-2,2′-bipyridine, 6-(5-trifluoromethyl-1,2,4-triazol-3-yl)-4,4′-dimethyl-2,2′-bipyridine), have been synthesized and characterized. As revealed by X-ray crystallography, each Ln(III) has a distorted tricapped trigonal prism generated by three nitrogens from one 2,2?-bipyridyl-1,2,4-triazolate chelate and six oxygens from two DMF molecules and two chelating nitrates, where 2,2?-bipyridyl-1,2,4-triazole serves as a mono-anionic tridentate chelate via deprotonation of the 1,2,4-triazolyl-NH. Complexes 1–4 are all emissive at room temperature in solution and solid states, and the introduction of two methyl groups into the 2,2?-bipyridyl ring is efficient in enhancing luminescence efficiencies of Ln(III) complexes.     

Four tri-spin lanthanide–nitronyl nitroxide (LnIII = GdIII,DyIII, ErIII,and HoIII) complexes: syntheses,structures, and magnetic properties

Four radical–Ln(III)–radical complexes, [Ln(hfac)₃(NITPhSCH₃)₂] (Ln?=?Gd (1), Dy (2), Er (3), Ho (4); hfac?=?hexafluoroacetylacetonate; NITPhSCH₃?=?4′-thiomethylphenyl-4,4,5,5tetramethyl-imidazoline-1-oxyl-3-oxide), have been synthesized, and structurally and magnetically characterized. The X-ray crystal structures show that the structures of the four complexes are similar, consisting of isolated molecules in which Ln(III) ions are coordinated by six oxygen atoms from three hfac and two oxygen atoms from nitronyl radicals. The temperature dependencies of magnetic susceptibilities for the four complexes show that in the Gd(III) complex, ferromagnetic interactions between Gd(III)–radical and antiferromagnetic interactions between the radicals coexist with J _Rad–Gd?=?1.09?cm^?1, J _Rad–Rad?=??1.85?cm^?1.     

Two 1-D europium coordination polymers: synthesis,crystal structure and fluorescence

Two new complexes {[Eu(2, 4-DFBA)₃ · (H₂O)₂] · H₂O} _n (1) and [Eu(2-BrBA)₃ · H₂O] _n (2) (2, 4-DFBA = 2, 4-difluorobenzoate, 2-BrBA = 2-bromobenzoate) have been synthesized and characterized by single crystal X-ray diffraction. 1 has a 1-D chain structure, in which Eu(III) ions are bridged by single COO^? groups and a 2-D supramolecular network is formed by hydrogen bond interactions. In 1, each Eu(III) is eight-coordinate with six oxygens from four 2,4-DFBA ligands and two waters. 2 has a 1-D chain structure, in which Eu(III) ions are bridged by bridging-chelating-bridging COO^? groups. In 2, each Eu(III) ion is nine-coordinate with eight oxygens from five 2-BrBA ligands and one water. The two complexes exhibit intense luminescence at room temperature. The ⁵D₀ → ⁷F _j (j = 0–4) transition emissions of Eu(III) have been observed.