Ames, Kelly A. ; Collinson, Simon R.; Blake, Alexander J.; Wilson, Claire; Love, Jason B. ; Bruce, Duncan W. ; Donnio, Bertrand; Guillon, Daniel and Schröder, Martin
Design of Neutral Metallomesogens from 5,5-Dimethyldipyrromethane: Metal Ion Mediated Control of Folding and Hairpin Structures.
European Journal of Inorganic Chemistry, 2008(32) pp. 5056–5066.
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New ligands derived from 5,5-dimethyldipyrromethane and their corresponding neutral complexes with Zn(II) and Pd(II) are described. The ligands incorporate either hexacatenar [H2(1n), n = 1, 10, 12, 14 and 16], tetracatenar [H2(2n), n = 1 and 16] or an extended dicatenar structure [H2(3n), n = 1 and 16]. Single crystal X-ray structure determinations on [Zn2(11)2] and [Zn2(31)2] confirm a distorted tetrahedral geometry at Zn(II) to afford double-stranded helical structures, while the Pd(II) species [Pd(31)] shows a distorted square planar geometry with the ligand adopting an alternative hairpin conformation. The metal-free hexacatenar ligands H2(1n) (n = 10, 12, 14, 16) and the corresponding complexes [Zn2(116)2] and [Pd(1n)] (n = 12, 14, 16) are not mesomorphic. However, the tetracatenar complex [Zn2(216)2] generates a smectic mesophase, as confirmed by X-ray diffraction, while [Pd(216)] and the metal-free ligand H2(216) show no mesomorphic behaviour. Two of the extended dicatenar compounds, H2(316) and [Zn2(316)2] are non-mesomorphic, while [Pd(316)] displays a smectic A phase.
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