Shun-Ping Zhao

A rhombus channel metal–organic framework comprised of Sr2+ and thiophene-2, 5-dicarboxylic acid exhibiting novel dielectric bistability

A metal–organic framework (MOF) compound, comprised of Sr2+ and thiophene-2,5-dicarboxylic acid (H2TDA) with a formula of Sr(TDA)(DMF), was prepared via the solvothermal method, this MOF compound crystallizes in the monoclinic space group P21/c with unit cell parameters a = 6.0078(4) A, b = 16.9401(12) A, c = 13.0061(8) A, β = 116.158(3)° and V = 1188.10(14) A3. The spaces of rhombus channels in the MOF crystal are occupied by the disordered DMF molecules. The striking structural feature is that the connectivity between inorganic hendecahedron units of SrO7 and TDA2− ligands gives rise to the uncommon I1O2 type 3-D framework of 1. The dielectric relaxation and novel dielectric bistability behaviors were observed for this MOF compound in the lower frequency regime (f 160 °C), which originated from the orientation motion of the disordered polar DMF molecules under an ac electric field. This study suggested the possibility of dielectric bistability in the designed MOFs with pores or channels.

A facile and efficient strategy for the design of ferroelectric and giant dielectric hybrids via intercalating polar molecules into noncentrosymmetric layered inorganic compounds

Taking into account that an intercalation reaction, an entropy and volume reducing process, can be promoted by increased pressure in a reactor, we developed a facile and efficient strategy for rapid preparation of DMSO and urea intercalated Kaolinites under mild reaction conditions by means of an autoclave, reducing the reaction time from several days to 6 h. The Kaolinite is a noncentrosymmetric layered inorganic host, the polar DMSO or urea molecules were inserted into the inter-layers of Kaolinite to create the hybrid ferroelectric or giant dielectric materials. Our results will shed light on the design and preparation of new hybrid functional materials with technologically important ferroelectricity and giant dielectric properties.

Intercalated supramolecular compounds of kaolinite with ethanolamine and ethylene glycol: structures and dielectric properties

Kaolinite (K), a polar and layered aluminosilicate mineral, was used as the host; ethanolamine (EOA) and ethylene glycol (EG) were inserted into the kaolinite interlayer to give the intercalated supramolecular compounds kaolinite-ethanolamine (K-EOA) and kaolinite-ethylene glycol (K-EG), respectively. The intercalation of EOA and EG resulted in an increase in the d(001)-value by 3.4 and 3.68 Å, which corresponds to expansion of the interlayer space by 156.7 Å(3) in K-EOA and 169.6 Å(3) in K-EG, respectively. The characteristic infrared-active ν(O-H) modes ν1, ν2 and ν3 besides ν5, which were quite sensitive to the host-guest interaction, were not significantly affected by intercalation in K-EOA and K-EG, and two intercalated compounds showed lower deintercalation temperature (115 and 109 °C for K-EOA and K-EG, respectively). These are due to weakly intermolecular interactions between the intercalant molecules and the kaolinite framework, which is in agreement with the theoretical analysis of crystal structures of the intercalated compounds. K-EOA and K-EG showed novel dielectric relaxation behavior, which originates from the dynamic orientation motion of intercalant molecules.

Novel dielectric relaxation behaviors driven by host–guest interactions in intercalated compounds of kaolinite with aminopyridine isomers

Kaolinite (K), a polar and layered aluminosilicate mineral, was used as the host for three aminopyridine isomers: 2-aminopyridine (2-APy), 3-aminopyridine (3-APy), and 4-aminopyridine (4-APy). We inserted these isomers into the kaolinite interlayer to produce the intercalated compounds 2-APy-K, 3-APy-K, and 4-APy-K, respectively. These intercalated compounds show distinct ν(O–H) bands arising from the inner and inner-surface hydroxyl groups of kaolinite. They also have diverse deintercalation temperatures of about 112 °C for 2-APy-K, 136 °C for 3-APy-K, and 181 °C for 4-APy-K, indicating that the host–guest interaction is different for each of these intercalated compounds. One-step dielectric relaxation appears in 2-APy-K and 3-APy-K, while two-step dielectric relaxation appears in 4-APy-K in the low-frequency regime (f < 104 Hz). The dielectric relaxation in these compounds arises from the dipole motion of intercalatant molecules under an applied ac electrical field. Our results shed light on the design and preparation of new hybrid materials with technologically important physical properties using a host–guest chemical approach.

A bis(maleonitriledithiolato)nickelate charge-transfer salt with mixed stacks exhibiting novel non-ferroelectric-type dielectric phase transition and bistability

A charge-transfer salt consisting of 1,1′-dioctyl-4,4′-bipyridinium and bis(maleonitriledithiolato)nickelate is described. Its crystal is built from mixed stacks of the anion and cation, with the anions (A) and cations (C) adopting an …ACAC… fashion within a stack. This salt shows a novel non-ferroelectric-type dielectric phase transition at around 324 K and bistability.

CCDC 921251: Experimental Crystal Structure Determination

Related Article: Shun-Ping Zhao, Yan-Jun She, Chen Xue, Xiao-Qing Huang, Rong-Yi Huang, Heng Xu|2014|Inorg.Chem.Commun.|44|96|doi:10.1016/j.inoche.2014.03.007