Browsing by Author "Harman, DG"

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    Cu (II) ion directed self-assembly of a Y8/Cu6 heterometallic coordination cage via an Y (III) metalloligand
    (Elsevier, 2019-01-01) Zhang, YJ; Harman, DG; Avdeev, M; Karatchevtseva, I
    A non-centrosymmetric yttrium [Y(III)] metalloligand, [Y(H3L)(NO3)]·2NO3·THF (1) {tris{[2-{(imidazole)methylidene}amino]-ethyl}amine = H3L}, was synthesized and subsequently used in a Cu(II) directed self-assembly process to form a Y8/Cu6- type heterometallic coordination cage [Cu6Y8L8(NO3)5(H2O)3]·7NO3·21H2O (2). The eight corners of the distorted cubic cage are defined by eight Y(III) ions while Cu(II) ions occupy the centers of six faces with two opposite Cu(II) ions considerably outside the faces. The asymmetric Y(III) metal centres due to the extra coordination of either water molecules or nitrate anions induce chirality in the cage, with equal numbers of both enantiomers present in the solid state. The cage formation in both solution and in the solid state was demonstrated by ESI-MS and single crystal X-ray diffraction. Magnetic property measurements indicate that cage 2 remains paramagnetic down to 2 K. In addition, vibrational modes, electronic structure and thermal stability of the coordination cage 2 have been further investigated and reported. Crown Copyright © 2018 Published by Elsevier B.V.
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    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
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    Self-assembly of a unique 3d/4f heterometallic square prismatic box-like coordination cage
    (Royal Society of Chemistry, 2016-05-23) Li, L; Zhang, Y; Avdeev, M; Lindoy, LF; Harman, DG; Zheng, RK; Cheng, Z; Aldrich-Wright, JR; Li, F
    AbstractWe present the synthesis and characterization of a unique, slightly distorted square prismatic, box-like coordination cage of type [Cu6Dy8L8(MeOH)8(H2O)6](NO3)12·χsolvent obtained via the supramolecular assembly between a non-centrosymmetric Dy(III) metalloligand and Cu(II) nitrate. Magnetic susceptibility measurements indicate that the complex behaves as a single-molecule magnet. © 2016 Royal Society of Chemistry
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    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