Crystal structures, CO2 adsorption, and dielectric properties of [Cu(II)2(R-benzoate)4(pyrazine)] polymers (R = m-F, 2,3-F2, m-Cl, and m-CH3)

Kiyonori Takahashi, Norihisa Hoshino, Takashi Takeda, Shin Ichiro Noro, Takayoshi Nakamura, Sadamu Takeda, Tomoyuki Akutagawa

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    12 Citations (Scopus)

    Abstract

    m-Fluorobenzoate (m-FBA), 2,3-difluorobenzoate (2,3-F2BA), m-methylbenzoate (m-MBA), and m-chlorobenzoate (m-ClBA) were introduced into the Cu(II) binuclear unit as bridging ligands between two Cu(II) sites, which were further connected by an axial pyrazine (pz) ligand to form one-dimensional coordination polymers of [Cu(II)2(m-FBA)4(pz)] (1), [Cu(II)2(2,3-F2BA) 4(pz)] (2), [Cu(II)2(m-MBA) 4(pz)] (3), and [Cu(II)2(m-ClBA) 4(pz)] (4), respectively. The parallel arrangements of one-dimensional (1D) polymers result in 1D channels between the polymers that crystallization CH3CN molecules can occupy to form single crystals of 1·4CH3CN, 2·4CH3CN, 3·2CH3CN, and 4·2CH3CN. Both π-dimer and dipole-dipole interactions were simultaneously observed in the interchain interactions of m-FBA and/or 2,3-F2BA ligands in crystals 1 and 2. The sizes of the one-dimensional channels between the polymers are thus modulated according to the interchain interactions between the polar BA ligands. CH3CN molecules within the channels were easily replaced by H 2O under ambient conditions. CO2 adsorption-desorption isotherms of crystals 1, 2, and 3 at 195 K indicated gate-adsorption with a hysteresis, whereas two-step gate-adsorption behavior was observed for CO 2 in crystal 4. Temperature- and frequency-dependent dielectric responses were not observed in crystals 1-4 under vacuum conditions, whereas dielectric anomalies were observed around 290 K for crystals 1 and 2 with adsorbed CO2. CO2 desorption from the channels in crystals 1 and 2 activated the molecular motions of polar BA ligands and dielectric responses around 290 K, which were confirmed from CO2 adsorption-desorption isotherms around 290 K and differential scanning calorimetries under CO2 conditions.

    Original languageEnglish
    Pages (from-to)9081-9089
    Number of pages9
    JournalDalton Transactions
    Volume43
    Issue number24
    DOIs
    Publication statusPublished - 2014 Jun 28

    ASJC Scopus subject areas

    • Inorganic Chemistry

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