(Figure Presented) Thermally robust porous metal-organic frameworks (MOFs) with zeolitic topologies were constructed by means of a ligand-directed strategy involving molecular tailoring of simple bridging imidazolates with coordinatively unimportant substituents. This led to the isolation of three new MOFs having unusually high symmetries, intriguing topologies such as the supercage shown in the picture, and high thermal stability. © 2006 Wiley-VCH Verlag GmbH & Co. KGaA.

Huang Xiao-Chun    Yanyong Lin    Jiepeng Zhang    陈小明    

Angewandte Chemie - International Edition

2006

(VCr)O nano-powders have been synthesized successfully for the first time in powder form by pyrolising polycrystalline Cr-doped precursors, Cr-doped (NH)[(VO)(CO)(OH)]·10HO in H atmosphere at 1373 K. Development of single-crystal of the Cr-doped precursor showed that Cr (III) possibly entered the precursor lattice or a solid solution formed in the precursor. Comparing the ratio of Cr/V in the raw materials (VOCl solution) to the Cr/V in the polycrystalline Cr-doped precursor indicated that the chemical doping method was feasible and Cr content in the precursor was controlled easily. The lattice parameters of Cr-doped VO powders determined by X-ray diffraction (XRD) were consistent with those of single-crystalline Cr-doped VO, revealing that Cr (III) entered the VO lattice. Both the results of differential scanning calorimetry (DSC) and magnetic susceptibility of the (VCr)O demonstrated that the Cr-doped VO powders exhibit intrinsic phase transition properties. Homogeneously distributed spherical (VCr)O powders with a particle size of about 40 nm have been obtained. © 2006 Elsevier B.V. All rights reserved.

Wei Liuya    Xiangfeng Chu    Lei Deming    Zheng Chenmou    陈小明    

Materials Science and Engineering B: Solid-State Materials for Advanced Technology

2006

Magnetic Δ-chains in a 3D coordination polymer [Co Na(4-cpa)(μ-OH)(HO)] are well separated by Na ions and organic spacers, and exhibit not only magnetic behaviour of Δ-chain topology but also slow magnetic relaxation. © The Royal Society of Chemistry 2006.

程小宁    Wei Zhang    Yanzhen Zheng    陈小明    

Chemical Communications

2006

The hydrothermal reaction of 1H-1,10-phenanthroline-2-one (Hophen), zinc acetate, benzoic acid (Hba), and triethylamine (3.0 mL) yields the tetranuclear complex [Zn(μ-OH)(ophen) (ba)] (2), which features a chair-like Zn (μ-OH) cluster with two ba ligands centrosymmetrically oriented. [(OAc){Zn(μ-OH)(ophen) }(ox){Zn(μ-OH)(ophen)}-(OAc)] (3; ox = oxalate) was isolated when less triethylamine (1.0 mL) was used. Two Zn(μ-OH)(ophen) clusters in 3 are linked together by an oxalate to form a dumbbell-like structure in which the acetate and oxalate ligands point outward from the Zn(μ-OH) (ophen) cluster with an acute bending angle. A geometric analysis reveals that Zn(μ-OH)-(ophen) and dicarboxylate with an obtuse bending angle cannot form an infinite zigzag chain, whereas the ring isomer can. With isophthalate (ipa), thiophene-2,5- dicarboxylate (tda), and 4,4′-oxybis(benzoate) (oba) instead of the acetate of 3 three new complexes, namely [{Zn(μ-OH) (ophen)}-(ipa){Zn(μ-OH) (ophen)}]·0.5HO (4), [{Zn(μ -OH)-(ophen)}(tda){Zn(μ -OH)(ophen)}] (5), and [{Zn(μ -OH)-(ophen)}(oba){Zn(μ -OH)(ophen)}] (6), were obtained in which two Zn (μ-OH)(ophen) clusters are linked by a pair of ipa, tda, or oba ligands to form isostructural, cluster-based 2:2 metallomacrocycles. Photoluminescence studies of 2-6 revealed that their luminescent properties are derived from ophen-based π-π* excited states. © Wiley-VCH Verlag GmbH & Co. KGaA, 2006.

Jiepeng Zhang    Yanyong Lin    Huang Xiao-Chun    陈小明    

European Journal of Inorganic Chemistry

2006

The isostructural, chiral molecular magnetic materials with the formula [MM′(ca)(1,4-dimb)] [Hca = D-(+)-camphoric acid, 1,4-dimb = 1,4-di-(1-imidazolyl-methyl)-benzene, M = Ni, M′ = Co, 0 ≤ x ≤ 2] consist of ca-bridged (4,4) layers with [M(OCR)] as secondary building units that are pillared by the 1,4-dimb ligands into a unique 3D framework. The high-spin octahedral symmetry and the proportions of the mixed-metal ions were characterized by UV-vis spectroscopy. The compounds exhibit the onset of antiferromagnetic ordering at 7.5-23 K, as well as weak ferromagnetism, spin-flop, and glassy behavior that result from the randomness of the mixed-metal pairs, magnetic anisotropy of the metallic cations, and antisymmetric exchange. The composites should be regarded as molecular alloys of the pure Ni(II) and Co(II) compounds. The magnetic behavior of the solid solutions shows unambiguously that the organic bridges, bond angles, and bond distances greatly influence the effective interactions and bring about cooperative magnetic behavior in the chiral 3D frameworks. © 2006 American Chemical Society.

Minghua Zeng    bo Wang    王新益    Wei Zhang    陈小明     高松   

Inorganic Chemistry

2006

Parallel chains of Co dimers are interlinked by trans-1,2-cyclohexanedicarboxylate ligands in a laminated coordination polymer (see picture; C gray, Co tourquise, O red), which exhibits single-chain-magnet behavior due to strong Ising-like intrachain ferromagnetic interaction that can not easily be reversed by the relatively weak interchain antiferromagnetic interaction. (Figure Presented). © 2006 Wiley-VCH Verlag GmbH & Co. KGaA.

Yanzhen Zheng    童明良    Wei Zhang    陈小明    

Angewandte Chemie - International Edition

2006

Two isostructural mixed-valence vanadium phosphonoacetates H (DABCO)[VO(HO)V(OH)(O PCHCO)]·2.5H O (1) and H(PIP)[VO(HO)V (OH)(OPCHCO) ]·2.5HO (2) have been synthesized. They crystallize in the orthorhombic space group Pnna with a = 7.0479(10) Å, b = 15.307(2) Å, and c = 17.537(3) Å for 1 and a = 7.0465(9) Å, b = 15.646(2) Å, and c = 17.396(2) Å for 2. X-ray single-crystal diffraction reveals that 1 and 2 have a three-dimensional open framework featuring 16-ring ellipsoid channels that are filled with doubly protonated 1,4-diazabicyclo[2,2,2]octanium/piperazinium cations and water molecules. According to the classification in metal-organic frameworks, 1 and 2 contain infinite (-O-V-) chains that are cross-linked by "metalloligand" [VO(HO)(OPCH CO)] into a 3-D net of the sra topology. The temperature dependence of the magnetic susceptibility of 1 shows that the χT value in the range of 60-320 K is constant of 1.105 cm K mol/V unit, and upon further cooling, the χT value rapidly increases to 1.81 cm K mol at 2 K. The corresponding effective magnetic moment (μ)/V unit varies from 2.97 μ at 320 K to 3.80 μ at 2 K. The magnetic data in the range of 2-320 K follow the Curie-Weiss law with C = 1.074 cm K mol and Θ = -1.34 K. © 2006 American Chemical Society.

张献明    Hou Juan-Juan    Weixiong Zhang    陈小明    

Inorganic Chemistry

2006

Two new heterocycle-based two-photon absorption chromophores, 4-[4-(4,5-diphenyl-1H-imidazol-2-yl)styryl]-pyridine (2) and (E)-4-{[2-(1H-benzimidazol-2-yl)vinyl]styryl}-N-methylpyridinium iodide (4), have been synthesized and characterized. The two molecules possess A-π-A′ structures. A π-deficient heteroaromatic ring (benzimidazole, 4,5-diphenyl-1H-imidazole) is used as an acceptor (A), and a pyridine ring is used as another acceptor (A′). One-photon-excited fluorescence, one-photon-fluorescence quantum yields, two-photon-excited fluorescence, and two-photon absorption cross-sections were investigated. Pumped with 740 and 800 nm laser excitation, compounds 2 and 4 had two-photon absorption cross-sections (41 and 38 GM) and two-photon-excited fluorescence (511 and 601 nm) in DMF, respectively. The crystal structure of compound 4 was determined by using X-ray single-crystal diffraction analysis. © 2006 The Chemical Society of Japan.

Yan Yun-Xing    Fan Hai-Hua    Lam Chi-Keung    Huang Hong    Jing Wang    Sheng Hu    Wang He-Zhou    陈小明    

Bulletin of the Chemical Society of Japan

2006

A microporous 3D cobalt(II) coordination polymer featuring pillared layers [Co(ma)(ina)]·2nHO (1·2H O) (ma = malate, ina = isonicotinate) was generated by hydrothermal treatment with a void volume of 25.8%, in which the in-situ generated ma ligands connect the Co ions into a 2D lattice with mixed and multiple exchange-bridges, affording a new geometrical topology different from the Kagomé lattice and leading to spin frustration. The rigid ina-pillared metallic-layered structure could retain 3D structural ordering upon guest removal and exchange. By soaking guest-free host (1) in MeOH and methanamide (HCONH) solutions, single crystals of dehydrated 1 were transformed into single crystals of 1·MeOH and 1·HCONH, respectively, without apparent host-structural changes. 1 can also be rehydrated into 1·2HO′. The guest-inclusion crystals have been characterized by X-ray single-crystal diffraction at 293 K and 93 K, confirming the single-crystal-to-single-crystal transformations and providing detailed information of the guest molecules confined in the subnanospace and host-guest and/or guest-guest hydrogen-bonding interactions. The magnetic behaviours of this family of porous magnetic materials are complex due to the influences of multiple metal sites, intra- and inter-layer exchanges, spin-orbit coupling, as well as geometrical frustration, which show magnetic ordering at <2 K, 3.5 K, 3.5 K, and 8 K for 1, 1·MeOH, 1·HCONH, and 1·2HO, respectively, due to the different size of guest molecules along with the different host-guest interaction, which may slightly modify the path of magnetic exchange, decrease the intensity of the spin-frustration in the 2D lattice, and cooperatively enhance the magnetic ordering temperature. © The Royal Society of Chemistry 2006.

Minghua Zeng    Feng Xiao-Long    Weixiong Zhang    陈小明    

Dalton Transactions

2006

A novel polyimidazole ligand bis(N-methylimidazol-2-yl)ketone (BIK) has been synthesized and its first metal complex [Zn(BIK)2](ClO4)2 has been structurally established by X-ray crystallography. The zinc atom is coordinated by two chelating BIK ligands in a distorted tetrahedral N4 environment with ZnN bonds at 1.997(8) Å and NZnN bond angles at 93.5(5)-137.3(5)°. © 1995.

Chen Xiao-Ming;Xu Zhi-Tao;Mak Thomas C.W.

Polyhedron

1995