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Tridentate Ligand (tridentate + ligand)
Selected AbstractsDesigning Simple Tridentate Ligands for Highly Luminescent Europium ComplexesCHEMISTRY - A EUROPEAN JOURNAL, Issue 41 2009Abstract A series of tridentate benzimidazole-substituted pyridine-2-carboxylic acids have been prepared with a halogen, methyl or alkoxy group in the 6-position of the benzimidazole ring, which additionally contains a solubilising N -alkyl chain. The ligands form neutral homoleptic nine-coordinate lanthanum, europium and terbium complexes as established from X-ray crystallographic analysis of eight structures. The coordination polyhedron around the lanthanide ion is close to a tricapped trigonal prism with ligands arranged in an up,up,down fashion. The coordinated ligands serve as light-harvesting chromophores in the complexes with absorption maxima in the range 321,341,nm (,=(4.9,6.0)×104,M,1,cm,1) and triplet-state energies between 21,300 and 18,800,cm,1; the largest redshifts occur for bromine and electron-donor alkoxy substituents. The ligands efficiently sensitise europium luminescence with overall quantum yields () and observed lifetimes (,obs) reaching 71,% and 3.00,ms, respectively, in the solid state and 52,% and 2.81,ms, respectively, in CH2Cl2 at room temperature. The radiative lifetimes of the Eu(5D0) level amount to ,rad=3.6,4.6,ms and the sensitisation efficiency ,sens=(,rad/,obs) is close to unity for most of the complexes in the solid state and equal to approximately 80,% in solution. The photophysical parameters of the complexes correlate with the triplet energy of the ligands, which in turn is determined by the nature of the benzimidazole substituent. Facile modification of the ligands makes them promising for the development of brightly emissive europium-containing materials. [source] Crystal structure of a ternary mononuclear copper (II) complex: 4-chloro-3-methyl-6[(N-2-picolyl)-1,-iminomethyl]phenolato copper(II)perchlorateCRYSTAL RESEARCH AND TECHNOLOGY, Issue 5 2006S. M. Malathy Sony Abstract The complex crystallizes in monoclinic space group P21/n with unit cell parameters a = 7.295(4), b = 19.627(5), c = 12.770(4) Å, , = 101.25(4)º, V = 1793.2(12) Å3, Z = 4, , = 1.684 Mg/m3 at T = 293(2)K. The structure was solved by Patterson method and refined by full-matrix least-squares procedures to final R = 0.0387 using 2906 observed reflections. The asymmetric unit of the complex contains a mononuclear tridentate ligand, a perchlorate group and a methanol molecule. The compound crystallizes as parallel layers of polymeric complex bridged through perchloarate groups. The molecular CuN2OO,O,,2 chromophore involves an elongated rhombic octahedral structure and the Cu-ligand bond shows greater disparity. The five-membered chelate ring and the pyridine ring lie in the same plane while the six membered chelate ring assumes sofa conformation. A strong O-H,O inter molecular interaction plays a key role in the formation of dimer along b-axis. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Highly Symmetrical Tetranuclear Cluster Complexes Supported by p - tert -Butylsulfonylcalix[4]arene as a Cluster-Forming LigandEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 9 2006Takashi Kajiwara Abstract Square-planar tetranuclear clusters [M4(L)(AcO)4(,4 -OH)], (M = MnII, CoII, and NiII) are synthesized using tetra-anionic p - tert -butylsulfonylcalix[4]arene (L4,) as a cluster-forming ligand. Three complexes are crystallographically isostructural, being crystallized in the triclinic crystal system with space group P. The calix[4]arene acts as a tetrakis fac -tridentate ligand through four phenoxo and four sulfonyl oxygen atoms to form square arrangement of four metal ions, which are further bridged by four chelating acetate ions and one hydroxo ion in a ,4 manner to complete the hexacoordination of each metal center. Although the whole molecule of each complex is crystallographically independent, the molecule is highly symmetrical with a pseudo-four-fold axis lying on the ,4 -OH, group. The tetranuclear clusters are stable enough to maintain the core structures even in highly dilute solution (,10 ,M), which was confirmed by mass spectroscopic study, however, bridging acetates were easily exchanged by other carboxylate chelates to form derivatives such as [M4(L)(BzO)4(OH)],. Metal,metal interactions were investigated by means of magnetic susceptibility, and it was revealed that both ferro- and antiferromagnetic interactions occur in the NiII complex depending on the bridging angles of Ni,O,Ni. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006) [source] Pentacoordination versus tetracoordination in silicon derivatives of an O,N,O,-tridentate ligandACTA CRYSTALLOGRAPHICA SECTION C, Issue 4 2010Uwe Böhme Bis[2-(2-hydroxy-3-methoxybenzylideneamino)phenolato-,O]dimethylsilicon, C30H30N2O6Si, (II), was isolated from the reaction of 2-(2-hydroxy-3-methoxybenzylideneamino)phenol, (I), with dichlorodimethylsilane at 339,K. It consists of two ligand molecules and the Me2Si unit forming a dialkoxydimethylsilane with a tetracoordinate Si atom. [2-(3-Methoxy-2-oxidobenzylideneamino)phenolato-,3O,N,O,]dimethylsilicon, C16H17NO3Si, (III), was isolated from the same reaction conducted at 263,K. In this complex, the dianion of (I) is coordinated via two O atoms and an azomethine N atom to the pentacoordinate Si atom. According to quantum chemical calculations, (II) is the thermodynamically stable product and (III) is the kinetically favoured product. [source] The new three-dimensional supramolecule bis{,-2-[(4-hydroxybenzoyl)hydrazonomethyl]phenolato}bis[aquacopper(II)] dinitrateACTA CRYSTALLOGRAPHICA SECTION C, Issue 10 2008Hua Yin In the title centrosymmetric binuclear complex, [Cu2(C14H11N2O3)2(H2O)2](NO3)2, the two metal centres are bridged by the phenolate O atoms of the ligand, forming a Cu2O2 quadrangle. Each Cu atom has a distorted square-pyramidal geometry, with the basal donor atoms coming from the O,N,O,-tridentate ligand and a symmetry-related phenolate O atom. The more weakly bound apical donor O atom is supplied by a coordinated water molecule. When a further weak Cu...O interaction with the 4-hydroxy O atom of a neighbouring cation is considered, the extended coordination sphere of the Cu atom can be described as distorted octahedral. This interaction leads to two-dimensional layers, which extend parallel to the (100) direction. The two-dimensional polymeric structure contrasts with other reported structures involving salicylaldehyde benzoylhydrazone ligands, which are usually discrete mono- or dinuclear Cu complexes. The nitrate anions are involved in a three-dimensional hydrogen-bonding network, featuring intermolecular N,H...O and O,H...O hydrogen bonds. [source] Polymorph of {2-[(2-hydroxyethyl)iminiomethyl]phenolato-,O}dioxido{2-[(2-oxidoethyl)iminomethyl]phenolato-,3O,N,O,}molybdenum(VI)ACTA CRYSTALLOGRAPHICA SECTION C, Issue 2 2008Dominique Agustin A second polymorphic form (form I) of the previously reported compound {2-[(2-hydroxyethyl)iminiomethyl]phenolato-,O}dioxido{2-[(2-oxidoethyl)iminomethyl]phenolato-,3O,N,O,}molybdenum(VI) (form II), [Mo(C9H9NO2)O2(C9H11NO2)], is presented. The title structure differs from the previously reported polymorph [G,owiak, Jerzykiewicz, Sobczak & Zió,kowski (2003). Inorg. Chim. Acta, 356, 387,392] by the fact that the asymmetric unit contains three molecules linked by O,H...O hydrogen bonds. These trimeric units are further linked through O,H...O hydrogen bonds to form a chain parallel to the [11] direction. As in the previous polymorph, each molecule is built up from an MoO22+ cation surrounded by an O,N,O,-tridentate ligand (O,C6H4CH=NCH2CH2O,) and weakly coordinated by a second zwitterionic ligand (O,C6H4CH=N+HC2H4OH). All complexes are chiral with the absolute configuration at Mo being C or A. The main difference between the two polymorphs results from the alternation of the chirality at Mo within the chain. [source] [2,6-Bis(5-methyl-2-pyridyl)phenyl-,3N,C1,N,]chloridoplatinum(II)ACTA CRYSTALLOGRAPHICA SECTION C, Issue 10 2007Taichi Abe In the title compound, [Pt(C18H15N2)Cl], the PtII centre adopts a distorted square-planar coordination geometry due to the pincer-type monoanionic N,C,N tridentate ligand. The planar complexes stack via,,, interactions to form two-dimensional accumulated sheets. This packing pattern is in contrast to that in related pincer-type N,C,N complexes, which exhibit a one-dimensional columnar stacking. [source] Synthesis, structural characterization and cytotoxic activity of diorganotin(IV) complexes of N -(5-halosalicylidene)tryptophaneAPPLIED ORGANOMETALLIC CHEMISTRY, Issue 1 2009Laijin Tian Abstract Four new diorganotin(IV) complexes of N -(5-halosalicylidene)tryptophane, R2Sn[5-X-2-OC6H3CHNCH(CH2Ind)COO] [Ind = 3-indolyl; R, X = Et, Cl (1); Et, Br(2); n -Bu, Cl (3); n -Bu, Br (4)], were synthesized and characterized by elemental analysis, IR and NMR (1H, 13C and 119Sn) spectra. The crystal structures of complexes 1,3 were determined by X-ray single crystal diffraction and showed that the tin atoms are in a distorted trigonal bipyramidal geometry and form five- and six-membered chelate rings with the tridentate ligand. Intermolecular weak interactions in 1,3 link molecules, respectively, into a two-dimensional array, a one-dimensional infinite chain and a one-dimensional double-chain supramolecular structure. Bioassay results of the compounds indicated that the dibutyltin complexes 3 and 4 have potent in vitro cytotoxic activity against two human tumor cell lines, CoLo205 and Bcap37, while the diethyltin complexes 1 and 2 display weak cytotoxic activity. Copyright © 2008 John Wiley & Sons, Ltd. [source] Diaqua(sulfato-,O)[2,4,6-tris(2-pyridyl)-1,3,5-triazine-,3N1,N2,N6]zinc(II) dihydrateACTA CRYSTALLOGRAPHICA SECTION C, Issue 10 2004Miguel Angel Harvey In the title compound, [Zn(SO4)(C18H12N6)(H2O)2]·2H2O, the metal complex is monomeric, with an octahedral ZnII centre coordinated by the tridentate ligand 2,4,6-tris(2-pyridyl)-1,3,5-triazine (tpt), two aqua molecules and a monodentate sulfate ion. A complex hydrogen-bonding scheme is built up out of the profuse availability of donors and acceptors (O,H,O/N and C,H,O) which, in addition to ,,, interactions between tpt groups, define a three-dimensional assembly. [source] Crystallographic report: Diphenyltin(IV) N -salicylidenevalinateAPPLIED ORGANOMETALLIC CHEMISTRY, Issue 9 2004Han Dong Yin Abstract The title compound, {Ph2Sn[2-OC6H4CHNCHCH(CH3)2COO]}, is a five-coordinated monomer with trigonal bipyramidal tin and with the axial positions occupied by oxygen atoms derived from the tridentate ligand. Copyright © 2004 John Wiley & Sons, Ltd. [source] A capped trigonal prismatic cadmium complex with tetra- and tridentate ligands: bis(triethanolamine)-,3N,O,O,;,4N,O,O,,O,,-cadmium(II) squarate monohydrateACTA CRYSTALLOGRAPHICA SECTION C, Issue 8 2004brahim Uçar In the crystal structure of the title compound, [Cd(C6H15NO3)2](C4O4)·H2O, a supramolecular structure is observed. The asymmetric unit consists of one unit of the cationic Cd complex, one water molecule and two half-squarate anions, each sitting on a crystallographic inversion center. The different coordinations of the two triethanolamine (TEA) ligands results in an unusual example of coordination number seven for the CdII ion. Both TEA ligands coordinate to the CdII ion, forming a distorted monocapped trigonal prismatic geometry with approximate C2v symmetry. One of the TEA ligands acts as an N,O,O,-tridentate ligand, whereas the other behaves as an N,O,O,,O,,-tetradentate donor. The anions and cations are linked to one another by hydrogen bonds between hydroxy H atoms of the TEA ligands and squarate O atoms. The crystal structure is stabilized by O,H,O hydrogen bonds between the unligated water molecule and a squarate O atom, together with a weak ,,ring interaction between the ethylene group of a TEA ligand and a squarate anion. [source] Crystal Structure and Ethylene Oligomerization Catalytic Activity of {2-Carbethoxy-6-[1-[(2,6-diethyl-phenyl)imino]ethyl]pyridine}CoCl2CHINESE JOURNAL OF CHEMISTRY, Issue 1 2007Bi-Yun Sun Abstract The unsymmetric precursor ethyl 6-acetylpyridine-2-carboxylate (4) was synthesized from 2,6-dimethylpyridine (1). On the basis of this precursor, a new mono(imino)pyridine ligand (5) and the corresponding Co(II) complex {2-carbethoxy-6-[1-[(2,6-diethylphenyl)imino]ethyl]pyridine}CoCl2 (6) were prepared. The crystal structure of complex indicates that the 2-carbethoxy-6-iminopyridine is coordinated to the cobalt as a tridentate ligand using [N, N, O] atoms, and the coordination geometry of the central cobalt is a distorted trigonal bipyramid, with the pyridyl nitrogen atom and the two chlorine atoms forming the equatorial plane. Being applied to the ethylene oligomerization, this cobalt complex shows catalytic activity of 1.820×104 g/mol-Co·h at 101325 Pa of ethylene at 15.5 °C for 1 h, when 1000 equiv. of methylaluminoxane (MAO) is employed as the cocatalyst. [source] Comparative Studies of Tridentate Sulfur and Nitrogen-Containing Ligands as Ionophores for Construction of Cadmium Ion-Selective Membrane SensorsELECTROANALYSIS, Issue 11 2007Ashok, Kumar Singh Abstract New polymeric membrane cadmium-ion selective sensors have been prepared by incorporating nitrogen and sulfur containing tridentate ligands as the ionophores into the plasticized PVC membranes. Poly(vinyl chloride) (PVC) based membranes of potassium hydrotris[N -(2,6-xylyl)thioimdazolyl) borate] (KTt2,6-xylyl) and potassium hydrotris(3-phenyl-5-methylpyrazolyl) borate (KTpPh,Me) with sodium tetraphenyl borate (NaTPB) as an anionic excluder and dibutylphthalate (DBP), tributylphthalate (TBP), dioctylsebacate (DOS), and o -nitrophenyloctyl ether (o -NPOE) as plasticizing solvent mediators were investigated in different compositions. KTt2,6-xylyl was found to be a selective and sensitive ion carrier for Cd(II) membrane sensor. A membrane composed of KTt2,6-xylyl:NaTPB:PVC:DBP with the % mole ratio 2.3,:,1.1,:,34.8,:,61.8 (w/w) works well over a very wide concentration range (7.8×10,8,1.0×10,2,M) with a Nernstian slope of 29.4±0.2,mV/decades of activity between pH values of 3.5 to 9.0 with a detection limit of 4.37×10,8,M. The sensor displays very good discrimination toward Cd(II) ions with regard to most common cations. The proposed sensor shows a short response time for whole concentration range (ca. 8,s). The effects of the cationic (tetrabutylammonium chloride, TBC), anionic (sodium dodecyl sulfate, SDS) and nonionic (Triton X-100) surfactants were investigated on the potentiometric properties of proposed cadmium-selective sensor. The proposed sensor based on KTt2,6-xylyl ionophore has also been used for the direct determination of cadmium ions in different water samples and human urine samples. [source] Large Second-Order NLO Activity in Poly(4-vinylpyridine) Grafted with PdII and CuII Chromophoric Complexes with Tridentate Bent Ligands Containing HeterocyclesEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 11 2008Fabio Borbone Abstract Two N -salicylidene- N,-acylhydrazines tridentate ligands containing heterocycles were prepared and utilized for the synthesis of mononuclear acentric complexes of CuII and PdII and pyridine serves as an additional ligand (MLxPy, M = metal, Lx = ligand). Characterization also includes single-crystal X-ray diffraction analysis. These complexesshow high second-order nonlinear optical activity (,, = 620,×,10,48esu for both CuLIIPy and PdLIIPy and ,, = 1600,×,10,48 and 1400,×,10,48 esu for CuLIPy and PdLIPy, respectively, at incident wavelength of 1907 nm). The properties of polymers (PMLx) obtained by grafting poly(4-vinylpyridine) with fragments of the complexes are also reported. The polymers exhibit good thermal stability, high glass-transition temperatures and the absence of crystallinity. The second-order nonlinear optical (NLO) properties of thin, transparent poled films, prepared by spin coating and thermal corona poling, were investigated for some of the polymers. The value of the d33 parameter was measured at 1064 and 1500 nm (i.e., with and without resonance contribute). In the latter case, the d33 values are 21 and 12 pm/V for PCuLII and PPdLII, respectively. A high time stability of the NLO properties of these materials was found. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008) [source] Novel Synthetic Strategy towards the Efficient Synthesis of Substituted Bis(pyrazolyl)(2-pyridyl)methane Ligands,EUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 21 2010Alexander Hoffmann Abstract A general one-pot synthesis of new substituted heteroscorpionate ligands is presented. These mixed-functionality ligands were obtained in a catalyzed Peterson rearrangement starting from the substituted pyrazole, thionyl chloride, and an aldehyde. Thus, the synthesis of polyfunctional tridentate ligands is enabled, and they contain, besides the two pyrazole groups, other functionalities relevant for coordination chemistry. Additionally, the steric hindrance is easily defined in the ligands by the substitution of the pyrazole rings. By combination of the versatility in donor function and steric demand, a systematic tuning of the properties of the bis(pyrazolyl)methane ligands is possible. The synthesis and full characterization of 11 bis(pyrazolyl)methane ligands are reported. Two of these were structurally characterized as well. [source] The reactivity of Ni(II) toward aspartic and glutamic monohydroxamatesINTERNATIONAL JOURNAL OF CHEMICAL KINETICS, Issue 9 2006Fawzia Al-Sogair The formation of complexes of Ni(II) with aspartic and glutamic acid hydroxamates was determined by potentiometric methods at I = 0.15 M NaCl and T = 25°C. The equilibrium study of Ni(II) with ASX or GLX revealed that the predominant species formed in solution were (M:L:H+): (1:1:0), (1:1:1), (2:1:0), and (2:1:1) in the whole pH range (,3,11). The formation of polymeric species was not observed. The octahedral structures were predicted in which the ligands act as tridentate ligands. The kinetics of complex formation between Ni(II) with ASX system as well as Ni(II) with GLX were also studied in a wide pH range. The observed rate constants for the Ni(II)-hydroxamates were found to be dependent on the total concentration of hydroxamates at a given pH through the following relations: kobs = Y0 + Z(TASX) and kobs = Y0 + Z(TGLX) + W(TGLX)2. The trans effect of the hydroxyl group present in the reacting species of Ni(OH)+ as well as a ring closure resulted from ligand chelation are introduced as explanations for the rate constants obtained for the reactions of Ni(II) with ASX or GLX. © 2006 Wiley Periodicals, Inc. Int J Chem Kinet 38: 540,552, 2006 [source] Synthesis and radiolabelling of Re(CO)3 - , -elemene derivatives as potential therapeutic radiopharmaceuticalsJOURNAL OF LABELLED COMPOUNDS AND RADIOPHARMACEUTICALS, Issue 5 2009Yunfeng Ren Abstract , -Elemene, (1S, 2S, 4R)-(,)-(1-methy-1-vinyl-2,4-diisopropenyl cyclohexane) is an anticancer agent from the Traditional Chinese Herb Medicinal. Three novel Re(CO)3 - , -elemene derivatives including their radioactive conjugates containing N,N,N tridentate ligands and tricarbonyl rhenium (complex 12, 13, 14) were synthesized. Their structures were characterized by infrared (IR), 1H-NMR and HRMS. Good radioactive yield (above 90%) and radioactive chemical purity with Re-188 (above 95%) were obtained for all of the three derivatives (complex 15, 16, 17). The antiproliferative activity of non-radioactive , -elemene-Re(CO)3 derivatives on Lewis lung cancer cells and HeLa cell lines were evaluated by WST-1 methods. The result shows substantial decrease in IC50 values compared with the parent compound , -elemene. The synthesis and radiosynthesis of , -elemene tricarbonyl rhenium conjugates provide the possibility to find a new kind of potential radiopharmaceuticals on , -elemene. Copyright © 2009 John Wiley & Sons, Ltd. [source] A capped trigonal prismatic cadmium complex with tetra- and tridentate ligands: bis(triethanolamine)-,3N,O,O,;,4N,O,O,,O,,-cadmium(II) squarate monohydrateACTA CRYSTALLOGRAPHICA SECTION C, Issue 8 2004brahim Uçar In the crystal structure of the title compound, [Cd(C6H15NO3)2](C4O4)·H2O, a supramolecular structure is observed. The asymmetric unit consists of one unit of the cationic Cd complex, one water molecule and two half-squarate anions, each sitting on a crystallographic inversion center. The different coordinations of the two triethanolamine (TEA) ligands results in an unusual example of coordination number seven for the CdII ion. Both TEA ligands coordinate to the CdII ion, forming a distorted monocapped trigonal prismatic geometry with approximate C2v symmetry. One of the TEA ligands acts as an N,O,O,-tridentate ligand, whereas the other behaves as an N,O,O,,O,,-tetradentate donor. The anions and cations are linked to one another by hydrogen bonds between hydroxy H atoms of the TEA ligands and squarate O atoms. The crystal structure is stabilized by O,H,O hydrogen bonds between the unligated water molecule and a squarate O atom, together with a weak ,,ring interaction between the ethylene group of a TEA ligand and a squarate anion. [source] 8-Hydroxyquinaldinic acid and its nickel(II) complexACTA CRYSTALLOGRAPHICA SECTION C, Issue 9 2002Nobuo Okabe The molecules of 8-hydroxyquinolinium-2-carboxylate, C10H7NO3, have a planar structure, in which the carboxyl group is ionized and the ring N atom is protonated. The derived nickel(II) complex, bis(8-hydroxyquinoline-2-carboxylato-,3O2,N,O8)nickel(II) trihydrate, [Ni(C10H6NO3)2]·3H2O, contains an octahedral central NiII ion coordinated by the hydroxyl O atom, the ring N atom and the carboxylate O atom of each of the two tridentate ligands, with a perpendicular orientation of the quinoline rings. [source] | ||||||||||