Browsing by Author "D'Alessio, D"

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    Ionophoric properties of a tetra-tetrazole functionalised calix[4]arene
    (Taylor and Francis Group, 2015-10-23) D'Alessio, D; Skelton, BW; Lengkeek, NA; Fraser, BH; Krause-Heuer, AM; Muzzioli, S; Stagni, S; Massi, M; Ogden, MI
    The synthesis and characterisation of p-t-butylcalix[4]arene functionalised at the lower rim with four tetrazole moieties is reported. The macrocycle is found to be a poorer ionophore for lanthanoid cations than the bis-tetrazole–substituted analogue. Solution-phase photophysical studies strongly suggested that the cations interacted only weakly with the calixarene ligand. A mixed sodium/triethylammonium salt of the calixarene ligand was crystallised in the presence of lanthanoid cations and structurally characterised. Strong intramolecular interactions are hypothesised to be the cause of the observed behaviour. © 2015 Taylor & Francis
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    Lanthanoid complexation by a tris-tetrazole-functionalised calix[4]arene
    (John Wiley & Sons, Inc, 2016-12-19) D'Alessio, D; Skelton, BW; Sobolev, AN; Krause-Heuer, AM; Fraser, BH; Massi, M; Ogden, MI
    The synthesis and characterization of 5,11,17,23-tetra-tert-butyl-25-hydroxy-26,27,28-tris(tetrazol-5-ylmethoxy)calix[4]arene is reported. Purification of the macrocycle required the use of preparative HPLC techniques. The macrocycle was found to be a poorer ligand for complexation of lanthanoid cations than the bis(tetrazole) analogue, but somewhat more effective than the tetrakis(tetrazole)-substituted derivative. Two metal complexes of the tris(tetrazole)–calixarene were structurally characterised. A polymeric sodium salt of the tris(tetrazole)–calixarene was isolated from a solution containing yttrium and a sodium acetate buffer. A praseodymium complex was isolated in the presence of an ammonium acetate buffer, where the calixarene acts as a unidentate ligand, bound to the metal atom through one tetrazole N-atom. Increasing the amount of buffer resulted in the crystallisation of a metal-free ammonium salt of the calixarene. © 2016 John Wiley & Sons, Inc.
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    Lanthanoid “bottlebrush” clusters: remarkably elongated metal–oxo core structures with controllable lengths
    (Journal of the American Chemical Society, 2014-10-04) D'Alessio, D; Sobolev, AN; Skelton, BW; Fuller, RO; Woodward, RC; Lengkeek, NA; Fraser, BH; Massi, M; Ogden, MI
    Large metal–oxo clusters consistently assume spherical or regular polyhedral morphologies rather than high-aspect-ratio structures. Access to elongated core structures has now been achieved by the reaction of lanthanoid salts with a tetrazole-functionalized calixarene in the presence of a simple carboxylate co-ligand. The resulting Ln19 and Ln12 clusters are constructed from apex-fused Ln5O6 trigonal bipyramids and are formed consistently under a range of reaction conditions and reagent ratios. Altering the carboxylate co-ligand structure reliably controls the cluster length, giving access to a new class of rod-like clusters of variable length. © 2014 American Chemical Society
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    Synthesis, structure and conformational mobility of tetra-substituted cyanomethoxy p-tert-butylcalix[4]arenes
    (Royal Society of Chemistry, 2016-04-04) D'Alessio, D; Krause-Heuer, AM; Skelton, BW; Fraser, BH; Massi, M; Ogden, MI
    The syntheses and single crystal X-ray structure determinations of 5,11,17,23-tetra-tert-butyl-25,26,27,28-tetrakis(cyanomethoxy)calix[4]arene (partial-cone conformer), 5,11,17,23-tetra-tert-butyl-25,27-bis(diethylcarbamoylmethoxy)-26,28-bis(cyanomethoxy)calix[4]arene (cone and partial-cone conformers), 5,11,17,23-tetra-tert-butyl-25,26,27-tris(cyanomethoxy)-28-hydroxycalix[4]arene, and 5,11,17,23-tetra-tert-butyl-25-diethylcarbamoylmethoxy-26,27,28-tris(cyanomethoxy)calix[4]arene (cone conformer) are reported. The calixarenes are found to be conformationally mobile when heated in DMSO, favouring the partial-cone conformer at equilibrium. The tris-substituted cyanomethoxy derivative was found to assume the partial-cone conformation in the solid state. Attempts to convert nitrile groups to tetrazole moieties in derivatives containing both amide and nitrile groups were unsuccessful. © The Authors - CC-BY licence