A new bromethyl-substituted molecular rotor, [Cu(dabcoCH₂Br)(H₂O)Br₃] (dabcoCH₂Br⁺=1-(2-bromethyl)-1,4-diazoniabicyclo[2.2.2]octane cation), which belongs to a family of halomethyl-substituted molecular rotors, was synthesized and structurally characterized. The reversible phase transition at ca. 250 K was well established for this molecular rotor by thermal analyses, variable-temperature X-ray diffraction, and variable temperature dielectric measurements. The order-disorder transformation of the rotator part (dabco moiety) causes ferroelastic phase transition with an Aizu notation of mmmF2/m from high-temperature orthorhombic phase (Pbnm) to low-temperature monoclinic phase (P2₁/n). More important, in reference to the density functional theory calculations and structural analyses, the key factors to tune the phase transition behaviors are discussed in detail for this family of halomethyl-substituted molecular rotors.

Bao Ying Wang;Chun Ting He;Bo Huang;Wei Jian Xu;Wei Xue;Zi Yi Du;Wei Xiong Zhang;小明 陈

Science China Chemistry

2015-7-29

Two dimeric lanthanoid (III) complexes, [Ln₂( bpy )₂( pybet )₄(H₂O)₄] ( bpy )₃(ClO₄)₆.H₂O ( bpy = 2, 2′-bipyridine, pybet = pyridinioacetate, and Ln Eu and Tb), have been prepared and characterized by X-ray crystallography. The complexes are isostructural, each comprising a quadruply carboxylato -bridged, centrosymmetrical dimeric cation, six perchlorate anions, three uncoordinated bpy molecules and a lattice water molecule. Each Ln ion is surrounded in a distorted square-antiprismatic environment by four carboxylato oxygen atoms, two nitrogen atoms of the bidentate bpy ligand and two aqua ligands. The Ln-O bond lengths range from 2.33 to 2.44 Â, and Ln-N bond lengths from 2.55 to 2.64 Â. The uncoordinated bpy molecules are linked to the aqua ligands by hydrogen bonds.

小明 陈;Yu Lua Wu;Yan Sheng Yan

Australian Journal of Chemistry

1995

Allylic rearrangement or the migration of a double bond from its original position in the carbon skeleton to an adjacent site was observed when 3,4,5,6-tetrahydrophthalate was hydrolyzed in a basic solution and in the presence of Co(_ii) and Mn(_ii) under hydrothermal conditions.

Yuan Chao Pang;Xiufang Hou;Lei Qin;Chao Wu;Wei Xue;Yan Zhen Zheng;Zhiping Zheng;小明 陈

Chemical Communications

2014-2-18

The synthesis, crystal structure, and sorption properties of [Cu ₂(bdc)₂(dmf)]H₂O·(dmf)(C ₂H₅OH)_0.5 (2· g, g = dmf· H ₂O·(C₂H₅OH)_0.5, bdc = 1,3-benzenedicarboxylate, dmf = N,N′-dimethylformamide) are reported. 2·g features upended bowl cavities with an outer diameter of 9.4 Å, which are enclosed by four tetracarboxylate-bridged Cu₂ paddle-wheels and extended by dicarboxylate linkers into a two-dimensional (2-D) coordination polymer. The metal-organic layers are further stacked in a slipped manner through van der Waals interactions to generate a three-dimensional (3-D) supramolecular structure having 2-D channels that accommodate the solvent molecules. After removal of the solvent molecules, solid 2 exhibits permanent porosity verified by an N₂ sorption isotherm with a Langmuir surface area of 629 m²·g^-1 and Brunauer-Emmett-Teller (BET) surface area of 374 m²·g^-1. Moreover, solid 2 also displays interesting methanol and benzene vapor sorption behaviors with large hysteresis and incomplete desorption, which is attributed to the chemisorption.

Dong Xu Xue;Yan Yong Lin;Xiao Ning Cheng;小明 陈

Crystal Growth and Design

2007-7

The anions of guanidinium 4-hydroxy-3-carboxybenzene-sulfonate, CH ₆N₃⁺·C₇H₅O ₆S^-, are linked into a linear chain by a short O _carboxyl⋯O_sulfonate interaction of 2.611 (2) Å; the hydroxyl group is linked intramolecularly to the carbonyl O atom, also by a short hydrogen bond [O⋯O = 2.601 (2) Å]. Adjacent chains are connected into a three-dimensional network structure through hydrogen-bonding interactions with the cation.

Xiu Lian Zhang;小明 陈;Seik Weng Ng

Acta Crystallographica Section E: Structure Reports Online

2004-3

Two three-dimensional coordination polymers, namely [Co(na)(ina)] (1) and [Co₃(na)₄(1,4-chdc)] (2) (Hna =nicotinic acid, Hina =isonicotinic acid, 1,4-H₂chdc=cyclohexane-1,4-dicarboxylic acid), with 8-connected CsCl-like topology, have been solvothermally synthesized. The temperature-dependent magnetic susceptibilities were also determined, showing antiferromagnetism in both compounds. CCDC: 688479, 1; 688480, 2.

Jian Bin Lin;小明 陈

Chinese Journal of Inorganic Chemistry

2008-8

Two cadmium(II) complexes of betaine (BET) have been prepared and characterized by X-ray crystallography. [Cd(BET) (μ-Cl)₂]_∞ (1), is a one-dimensional polymer in which each cadmium atom is coordinated by two pairs of bridging chlorine atoms [Cd-Cl=2.631(2), 2.614(2) Å] and two oxygen atoms from different bridging carboxylate groups [Cd-O=2.291(6), 2.329(6) Å] in the form of a compressed octahedron. [Cd(BET)(H₂O)Cl(μ-Cl)]₂ (2) is a dimer with each cadmium atom in a distorted octahedral coordination environment, being surrounded by a chelating bidentate carboxylate group [2.480(2), 2.332(3) Å], one aqua ligand [2.364(3) Å], two bridging chlorine atoms [2.659(1), 2.557(1) Å], and one terminal chlorine atom [2.480(1) Å].

小明 陈;Thomas C.W. Mak

Journal of Crystallographic and Spectroscopic Research

1991-2

The crystal structure of melaminium bis(hydrogen oxalate), C ₃H₈N₆²⁺·2C₂HO ₄^-, contains hydrogen oxalate anions that are linked by hydrogen bonds into a linear chain; adjacent chains are linked through the dication (which has crystallographic twofold symmetry), forming a layer structure.

Xiu Lian Zhang;小明 陈;Seik Weng Ng

Acta Crystallographica Section E: Structure Reports Online

2005-1

The crystal structure of [Ag(pyBET)(NO₃)]_n (pyBET = C₅H₅N⁺CH₂COO^-) has been characterized by X-ray crystallography. The complex comprises carboxylato-O,O′)-bridged one-dimensional polymeric chains with the Ag(I) atom forming two AgO(carboxylato) bonds [2.289(1) and 2.334(1) Å to different pyBET ligands] and one AgO(nitrato) bond [2.434(2) Å] in a distorted trigonal-planar configuration.

小明 陈;Thomas C.W. Mak

Polyhedron

1991

Two new isomorphic coordination polymers, [MCl2(β-ala)]_n (M=Co²⁺ (1) or Ni²⁺ (2), β-ala=3-aminopropi-onic acid), were constructed by assembling 3-aminopropionic acid and transition metal chlorides. Their reversible structural phase transitions were disclosed by differential scanning calorimetry (DSC), variable-temperature single-crystal X-ray diffraction and dielectric measurements. In 1 and 2, the adjacent M²⁺ ions are mix-bridged by two μ2-Cl-ions and a syn-syn carboxylate group from β-ala ligand, resulting in one-dimensional polymeric coor-dination chains. Both 1 and 2 undergo reversible phase transitions, which occur at critical temperature (T_c-heating, T_c-cooling) of 236, 224 K and 309, 302 K, respectively, with a change of space group between Pnam at the high-temperature phase (HTP) and Pna2₁ at the low-temperature phase (LTP). The phase transitions are mainly related to the dynamic change of ammonium ethyl group from two-fold disorder in HTP to static ordered state in LTP. Such order-disorder structural phase transitions lead to the coexistence of step-like dielectric anomaly and dielectric relaxation in the vicinity of the phase transition.

Yu Jun Su;Ke Xu;Wei Yuan;Rui Kang Huang;Wei Xiong Zhang;小明 陈

Chinese Journal of Inorganic Chemistry

2017