title: Insight into Understanding Dielectric Behavior of a Zn-MOF Using Variable-Temperature Crystal Structures, Electrical Conductance, and Solid-State13C NMR Spectra.
abstract: A Zn-based metal-organic framework (MOF)/porous coordination polymer (PCP), (EMIM)[Zn(SIP)] (1) (SIP3-= 5-sulfoisophthalate, EMIM+= 1-ethyl-3-methylimidazolium), was synthesized using the ionothermal reaction. The Zn2+ion adopts distorted square pyramid coordination geometry with five oxygen atoms from three carboxylates and one sulfo group. One of two carboxylates in SIP3-serves as a μ2-bridge ligand to link two Zn2+ions and form the dinuclear SBU, and such SBUs are connected by SIP3-ligands to build the three-dimensional framework with rutile (rtl) topology. The cations from the ion-liquid fill the channels. This MOF/PCP shows two-step dielectric anomalies together with two-step dielectric relaxations; the variable-temperature single-crystal structure analyses disclosed the dielectric anomaly occurring at ca. 280 K is caused by an isostructural phase transition. Another dielectric anomaly is related to the dynamic disorder of the cations in the channels. Electric modulus, conductance, and variable-temperature solid-state13C CP/MAS NMR spectra analyses revealed that two-step dielectric relaxations result from the dynamic motion of the cations as well as the direct-current conduction and electrode effect, respectively.
authors: State Key Laboratory of Materials-Oriented Chemical Engineering and College of Chemistry and Molecular Engineering, Nanjing Tech University , Nanjing 210009, P. R. China.
authors: Yuan-Bo
authors: YB
authors: Tong
authors: State Key Laboratory of Materials-Oriented Chemical Engineering and College of Chemistry and Molecular Engineering, Nanjing Tech University , Nanjing 210009, P. R. China.
authors: Shao-Xian
authors: SX
authors: Liu
authors: State Key Laboratory of Materials-Oriented Chemical Engineering and College of Chemistry and Molecular Engineering, Nanjing Tech University , Nanjing 210009, P. R. China.
authors: Yang
authors: Y
authors: Zou
authors: State Key Laboratory of Materials-Oriented Chemical Engineering and College of Chemistry and Molecular Engineering, Nanjing Tech University , Nanjing 210009, P. R. China.
authors: Chen
authors: C
authors: Xue
authors: State Key Laboratory of Materials-Oriented Chemical Engineering and College of Chemistry and Molecular Engineering, Nanjing Tech University , Nanjing 210009, P. R. China.|School of Environmental Science, Nanjing Xiao Zhuang University , Nanjing 211171, P. R. China.
authors: Hai-Bao
authors: HB
authors: Duan
authors: State Key Laboratory of Materials-Oriented Chemical Engineering and College of Chemistry and Molecular Engineering, Nanjing Tech University , Nanjing 210009, P. R. China.
authors: Jian-Lan
authors: JL
authors: Liu
authors: State Key Laboratory of Materials-Oriented Chemical Engineering and College of Chemistry and Molecular Engineering, Nanjing Tech University , Nanjing 210009, P. R. China.|College of Materials Science and Engineering, Nanjing Tech University , Nanjing 210009, P. R. China.|State Key Lab & Coordination Chemistry Institute, Nanjing University , Nanjing 210093, P. R. China.
authors: Xiao-Ming
authors: XM
authors: Ren