Polymorphs and structural phase transition of [Ni(dmit)2] - crystals induced by flexible (trans -cyclohexane-1,4-diammonium) (benzo[18]crown-6)2 supramolecule

Qiong Ye, Tomoyuki Akutagawa, Norihisa Hoshino, Takemitsu Kikuchi, Shin Ichiro Noro, Ren Gen Xiong, Takayoshi Nakamura

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    47 Citations (Scopus)

    Abstract

    Structurally flexible trans-cyclohexane-1,4-diammonium (CHDA2+) forms a hydrogen-bonded sandwich-type supramolecule with benzo[18]crown-6 in (CHDA2+)(benzo[18]crown-6)2[Ni(dmit)2] 2 (1) (dmit2-: 2-thioxo-1,3-dithiole-4,5-dithiolate). During the crystallization, the three crystal polymorphs 1a, 1b, and 1c were obtained in the space groups P21/c, P1̄, and P1̄, in which the orientation of the benzene rings of benzo[18]crown-6 in the sandwich-type supramolecular cations and the [Ni(dmit)2]- arrangements were different. Crystal 1c had a structural phase transition at ∼200 K, at which the unit cell volume of the low-temperature phase (1d) became twice that of the high-temperature phase (1c). The [Ni(dmit)2] π-dimer was observed in crystals 1a, 1b, 1c, and 1d. A double-minimum-type potential energy profile was observed for the rigid rotation of CHDA2+ around the N-N axis. Among four new crystals, the relatively low potential energy barrier of ∼120 kJ mol-1 for crystal 1b was consistent with the temperature- and frequency-dependent dielectric constants. The crystal polymorph and structural phase transition were coupled in (CHDA2+)(benzo[18]crown- 6)2[Ni(dmit)2]-2.

    Original languageEnglish
    Pages (from-to)4175-4182
    Number of pages8
    JournalCrystal Growth and Design
    Volume11
    Issue number9
    DOIs
    Publication statusPublished - 2011 Sep 7

    ASJC Scopus subject areas

    • Chemistry(all)
    • Materials Science(all)
    • Condensed Matter Physics

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