Browsing by Author "Shepherd, ND"

Now showing 1 - 6 of 6
  • No Thumbnail Available
    Item
    3d transition metal complexes with a julolidine–quinoline based ligand: structures, spectroscopy and optical properties
    (Royal Society of Chemistry, 2015-12-07) Fanna, DJ; Zhang, YJ; Li, L; Karatchevtseva, I; Shepherd, ND; Azim, A; Price, JR; Aldrich-Wright, JR; Reynolds, JK; Li, F
    A Schiff base type ligand with the combination of the julolidine and the quinoline groups has been reported as a potential chemosensor in detecting the cobalt(II) ion among other heavy and transition metal ions in solution. However, no crystal structure of such a ligand with any metal ions has been reported. In this work, its complexation with 3d transition metal ions (Mn(II), Co(II), Ni(II), Cu(II) and Zn(II)) has been investigated with five new complexes being synthesised, and spectroscopically and structurally characterised. [Mn2L2(CH3OH)2(CH3COO)2]•CH3OH (1) {HL (C22H21N3O) = ((E)-9-((quinolin-8-ylimino)methyl)-1,2,3,5,6,7-hexahydropyrido[3,2,1-ij]quinolin-8-ol)} shows a dinuclear structure with two Mn : L : acetate (1 : 1 : 1) units bridged by two methanol molecules. [CoL2(NO3)]•CH3OH•H2O (2) and [NiL2]•H2O (3) exhibit mononuclear structures with a Co : L or Ni : L ratio of 1 : 2. [CuL(CH3COO)]•1/3CH3OH (4) demonstrates a mononuclear structure and the Cu ion has a square planar coordination polyhedron with a L ligand and a highly non-symmetrical acetate anion. [Zn2L2(CH3COO)2]•CH3OH (5) has two types of dinuclear units, both with two ZnL units bridged by two acetate anions but in three different bridging coordination modes. Their vibrational modes, absorption and photoluminescence properties have also been investigated. © 2016 The Partner Organisations
  • No Thumbnail Available
    Item
    Dioxo-vanadium(V), oxo-rhenium(V) and dioxo-uranium(VI) complexes with a tridentate Schiff base ligand
    (Royal Society of Chemistry, 2016-08-03) Zhang, YJ; Fanna, DJ; Shepherd, ND; Karatchevtseva, I; Lu, KT; Kong, L; Price, JR
    The complexation of a julolidine–quinoline based tridentate ligand with three oxo-metal ions, dioxo-vanadium(V), oxo-rhenium(V) and dioxo-uranium(VI), has been investigated with four new complexes being synthesised and structurally characterised. (VO2L)·2/3H2O (1) {HL (C22H21N3O) = ((E)-9-((quinolin-8-ylimino)methyl)-1,2,3,5,6,7-hexahydropyrido[3,2,1-ij]quinolin-8-ol)} has a VO2L neutral mononuclear structure with a five-fold coordinated vanadium metal centre in a distorted trigonal bipyramidal geometry. (ReOL2)2(ReCl6)·7DMF (2) [DMF = dimethylformamide] exhibits a mixed valent rhenium complex with a (ReOL2)+ cationic unit in a distorted octahedral metal coordination geometry, charge balanced with (ReCl6)2− anions. [(UO2)L(H2O)2]2·2(NO3)·HL·4H2O (3) and [(UO2)L(CH3OH)2](NO3)·CH3OH (4) both have (UO2L)+ cationic mononuclear structures with either coordinated water or methanol molecules in pentagonal bipyramidal coordination geometries for the uranium metal centres. Intra-/intermolecular interactions including hydrogen bonding and π–π interactions are common and have been discussed. In addition, optical absorption and photoluminescence properties have been investigated. © 2016 The Royal Society of Chemistry
  • No Thumbnail Available
    Item
    A large spin-crossover [Fe4L4]8+ tetrahedral cage
    (Royal Society of Chemistry, 2015-05-20) Li, L; Saigo, N; Zhang, YJ; Fanna, DJ; Shepherd, ND; Clegg, JK; Zheng, RK; Hayami, S; Lindoy, LF; Aldrich-Wright, JR; Li, CG; Reynolds, JK; Harman, DG; Li, F
    A large discrete face-capped tetranuclear iron(II) cage, [Fe4L4](BF4)8·n(solvent), was synthesised via metal-ion directed self-assembly. The cage is formed from a rigid tritopic ligand that incorporates chelating imidazole-imine functional groups. The cage displays temperature induced spin-crossover and LIESST effects and is amongst the largest iron(II) tetrahedral cages with such properties reported. The synthesis, structure and magnetic properties of this new metallo-cage are presented. © 2015 The Royal Society of Chemistry
  • No Thumbnail Available
    Item
    One-dimensional uranium(VI) coordination polymers with pyridinecarboxylate ligands
    (Elsevier B.V., 2016-07-27) Shepherd, ND; Zhang, YJ; Karatchevtseva, I; Price, JR; Kong, L; Scales, N; Lumpkin, GR
    A method to produce picolinate ligand in situ under hydrothermal conditions has been used to synthesize four uranyl hydroxyl, oxo- and oxohydroxyl picolinato complexes. (UO2)(OH)(Pic) (1) (HPic = picolinic acid) contains 7-fold coordinated uranyl hydroxyl dimers linked through μ2-bridging Pic ligands forming a one-dimensional (1D) polymer. (NH4)[(UO2)3(O)2(OH)(Pic)2] (2) consists of 7-fold coordinated uranyl oxohydroxyl trinuclear units linked through both μ2- and μ3-Pic ligands forming a 1D polymer. (NH4)[(UO2)2(O)2(Pic)] (3) is constructed with 7-fold coordinated uranyl oxo-dinuclear units linked through oxo- and μ3-Pic ligands forming a 1D polymer. (NH4)[(UO2)4(O)2(OH)2(Pic)2(INT)]·H2O (4) (HINT = isonicotinic acid) is made of 7-fold coordinated uranyl oxohydroxyl tetranuclear units linked through both Pic and INT ligands forming a 1D polymer. All four polymers are thermal robust to 350 °C. Raman spectroscopy confirmed the presence of uranyl ion and Pic ligand. In addition, red enhanced fluorescence emissions have been observed for both 1 and 4. The synthesis method, with the advantage of controlling uranyl hydrolysis and generating ligand in situ, provides a more reliable way to make new coordination polymers of carboxylate ligands with various uranyl hydrolysis species. © 2016 Elsevier Ltd.
  • No Thumbnail Available
    Item
    Solvothermal synthesis of uranium(VI) phases with aromatic carboxylate ligands: a dinuclear complex with 4-hydroxybenzoic acid and a 3D framework with terephthalic acid
    (Elsevier B.V., 2016-02-01) Zhang, YJ; Karatchevtseva, I; Bhadbhade, MM; Tran, TT; Aharonovich, I; Fanna, DJ; Shepherd, ND; Lu, KT; Li, F; Lumpkin, GR
    With the coordination of dimethylformamide (DMF), two new uranium(VI) complexes with either 4-hydroxybenzoic acid (H2phb) or terephthalic acid (H2tph) have been synthesized under solvothermal conditions and structurally characterized. [(UO2)2(Hphb)2(phb)(DMF)(H2O)3]·4H2O (1) has a dinuclear structure constructed with both pentagonal and hexagonal bipyramidal uranium polyhedra linked through a µ2-bridging ligand via both chelating carboxylate arm and alcohol oxygen bonding, first observation of such a coordination mode of 4-hydroxybenzoate for 5 f ions. [(UO2)(tph)(DMF)] (2) has a three-dimensional (3D) framework built with pentagonal bipyramidal uranium polyhedra linked with µ4-terephthalate ligands. The 3D channeled structure is facilitated by the unique carboxylate bonding with nearly linear C–O–U angles and the coordination of DMF molecules. The presence of phb ligands in different coordination modes, uranyl ions in diverse environments and DMF in complex 1, and tph ligand, DMF and uranyl ion in complex 2 has been confirmed by Raman spectroscopy. In addition, their thermal stability and photoluminescence properties have been investigated. © 2015 Elsevier Inc.
  • No Thumbnail Available
    Item
    Synthesis and characterisation of two new tripodal metalloligands incorporating zinc(II)
    (Springer Nature, 2015-05-06) Fanna, DJ; Smith, A; Zhang, Y; Li, L; Shepherd, ND; Harman, DG; Li, F
    The in situ Schiff base condensation of 2-acetylpyrazine with tris(2-aminoethyl)amine in the presence of zinc(II) perchlorate was carried out in absolute ethanol and 95 % ethanol, respectively. Two new tripodal metalloligands, 1 and 2, were isolated. The formation of complexes 1 and 2 has been verified by NMR, mass spectral studies and X-ray (for 2), with the evidence indicating that a zinc ion is incorporated in the tripodal cavity defined by the tren backbone in each case. However the products differed in the number of Schiff base condensation reactions that had occurred. While the use of absolute ethanol resulted in condensation at all three primary amine sites of tris(2-aminoethyl)amine, employing 95 % ethanol yielded condensation at only one of the primary amine sites. These different outcomes can be ascribed, at least in part, to the effect of the different water contents in the respective reaction solvents resulting in a shift of the dynamic equilibrium involving imine formation towards the precursor amine and ketone reagents. In 1, steric considerations dictate that the three uncoordinated pyrazine nitrogen donors will have their coordination vectors oriented in a mutually divergent manner suitable for coordination to three different metal centres when acting as a metalloligand while for 2, the X-ray structure confirms that the single uncoordinated (pendent) pyrazine nitrogen is also oriented for ready coordination to a second metal centre. © 2015 Springer Science+Business Media Dordrecht