Tremendous efforts have been devoted to increasing the CO capture performance of porous materials, especially for low CO concentration environments. Here, we report that hydrazine can be used as a diamine short enough to functionalize the small-pore metal-organic framework [Mg(dobdc)] (Hdobdc = 2,5-dihydroxyl-1,4-benzenedicarboxylic acid). By virtue of the ultrahigh concentration of free amine groups (6.01 mmol g or 7.08 mmol cm) capable of reversible carbamic acid formation, the new material [Mg(dobdc)(NH)] achieves a series of new records for CO capture, such as single-component isotherm uptakes of 3.89 mmol g or 4.58 mmol cm at the atmospheric CO concentration of 0.4 mbar at 298 K and 1.04 mmol g or 1.22 mmol cm at 328 K, as well as more than a 4.2 mmol g or 4.9 mmol cm adsorption/desorption working capacity under dynamic mixed-gas conditions with CO concentrations similar to those in flue gases and ambient air.

聊培钦    Chen Xun-Wei    Liu Si-Yang    Li Xu-Yu    Xu Yantong    Tang Minni    Zebao Rui    Ji Hong-Bing    Jiepeng Zhang    陈小明    

Chemical Science

2016

A novel two-dimensional Heisenberg ferromagnet with a flexible organic layer, [CH(CH)NH][CuCl], undergoes ferroelastic, ferroelectric and ferromagnetic transitions at 337, 143 and 7.8 K, respectively. The ferromagnet was characterized by variable-temperature thermal measurements, in situ single-crystal X-ray structure analyses, anisotropic dielectric measurements, and pyroelectric and magnetic analyses. Differing from the other layered perovskite-like compounds, this compound revealed an extraordinary distorted polar structure with five times the cell volume at its polar phase because of the flexibility of the organic layer. Hence, this presents an approach to introduce spontaneous electric polarization into the Heisenberg ferromagnet for single-phase multiferroics. Moreover, due to the cooperation between the frozen [CH(CH)NH] cations and the tilting of the CuCl octahedra, this potential multiferroic compound simultaneously exhibits dielectric and magnetic bistabilities during both the ferroelastic and ferroelectric transitions.

Huang Bo    Wang Bao-Ying    Ziyi Du    Xue Wei    Xu Wei-Jian    Su Yu-Jun    Weixiong Zhang    Minghua Zeng    陈小明    

Journal of Materials Chemistry C

2016

Plastic crystals functioning with rotatable components offer new opportunities in areas such as modern optoelectronic materials. Here, by taking advantage of controllable rotation of the polar component within the ion-pair plastic-crystal system, we present two such crystals, namely, (EtN)(CrOX) (X = Cl or Br), which are unusual examples exhibiting two-staged thermosensitive dielectric responses above room temperature. The frequency-dependent response in the first stage is due to the structural phase transitions, whereas that in the second stage is induced by dynamic rotation of the polar halochromate anions in their NaCl-type plastic-crystal phases. The intrinsic mechanisms were also explicated by molecular dynamics simulations, providing a direct insight into the dynamic characteristics of these two compounds. These studies show that ionic plastic crystals functioning with polar groups are an attractive candidate as sensitive thermoresponsive dielectric materials.

Sun Yu-Zhi    Huang Bo    Xu Wei-Jian    Zhou Dong-Dong    Chen Shao-Li    Zhang Shi-Yong    Ziyi Du    Yongrong Xie    Chunting He    Weixiong Zhang    陈小明    

Inorganic Chemistry

2016

Qin Lei    Yu Youzhu    Liao Pei-Qin    Xue Wei    郑智平    陈小明     Yanzhen Zheng   

Advanced Materials

2016

Solvothermal reactions of Cu(NO) and 2-isopropylimidazole (Hipim) in different solvents/templates gave three supramolecular isomers: α-[Cu(ipim)] (1), β-[Cu(ipim)] (2), and γ-[Cu(ipim)]·1/3CH (3). Single-crystal X-ray diffraction analyses showed that 1, 2, and 3 are parallel-packed wavy chains, triple-stranded helices, and cubic-orthogonal-packed helical chains consisting of alternatively interconnected two-coordinated Cu(I) ions and ipim ligands. Because of the different intermolecular interactions, 1, 2, and 3 show different phosphorescence properties with emission maxima at 555, 540, and 530 nm, respectively. More interestingly, [Cu(ipim)] can melt at high temperature without decomposition. Compounds 1 and 2 melt above 185 and 146 °C, respectively; this liquid solidifies below 117 °C to form 1 again. However, 3 loses the benzene guest molecules above 90 °C and transforms to 1 in a crystal-to-crystal manner.

Su Yu-Jun    Cui Yi-Lan    Wang Yu    Ruibiao Lin    Weixiong Zhang    Jiepeng Zhang    陈小明    

Crystal Growth and Design

2015

Single-molecule magnets (SMMs) are regarded as a class of promising materials for spintronic and ultrahigh-density storage devices. Tuning the magnetic dynamics of single-molecule magnets is a crucial challenge for chemists. Lanthanide ions are not only highly magnetically anisotropic but also highly sensitive to the changes in the coordination environments. We developed a feasible approach to understand parts of the magneto-structure correlations and propose to regulate the relaxation behaviors via rational design. A series of Co(II)-Dy(III)-Co(II) complexes were obtained using in situ synthesis; in this system of complexes, the relaxation dynamics can be greatly improved, accompanied with desolvation, via single-crystal to single-crystal transformation. The effective energy barrier can be increased from 293cm (422K) to 416cm (600K), and the tunneling relaxation time can be grown from 8.5 × 10 s to 7.4 × 10s. These remarkable improvements are due to the change in the coordination environments of Dy(III) and Co(II). Ab initio calculations were performed to better understand the magnetic dynamics.

刘俊良    Wu Jie-Yi    Huang Guo-Zhang    陈龑骢    Jianhua Jia    Liviu Ungur    Liviu Chibotaru    陈小明     童明良   

Scientific Reports

2015

We demonstrate here that porous coordination frameworks, functionalized with monodentate hydroxide on the pore surface, can achieve ultrahigh CO adsorption affinity (124 kJ mol), adsorption capacity (9.1 mmol cm at 298 K and 1 bar), and CO/N selectivity (262 at 298 K) by the reversible formation/decomposition of bicarbonate in the adsorption/desorption processes. More importantly, these materials can capture up to 4.1 mmol cm or 13.4 wt% of CO from simulated flue gases (CO pressure 0.10-0.15 bar at 313 K) even at high relative humidity (82%) and quickly release it under mild regeneration conditions (N purge at 358 K), representing the best CO capture performances reported to date.

聊培钦    Huayao Chen    Zhou Dong-Dong    Liu Si-Yang    Chunting He    Rui Zebao    Ji Hong-Bing    Jiepeng Zhang    陈小明    

Energy and Environmental Science

2015

Solvothermal reactions of Cu(NO) and 4,4′-([3,4′-bipyridine]-2′,6′-diyl)dibenzoic acid (HL1), 3,3′-([4,4′-bipyridine]-2,6-diyl)dibenzoic acid (HL2), or 4,4′-([4,4′-bipyridine]-2,6-diyl)dibenzoic acid (HL3) yielded three new metal-carboxylate frameworks (MCF-28, MCF-29 and MCF-30) with a common formula [Cu(L)] (H L = pyridyldicarboxylic acid). X-ray crystallography showed that MCF-28, MCF-29, and MCF-30 are three-dimensional (3,6)-connected rtl, eea and pyr networks, respectively, based on 3-connected tripodal ligands and 6-connected Cu(RCOO)(py) units (RCOO and py denote carboxylate and pyridyl groups, respectively). Thermogravimetry, powder X-ray diffraction, and gas adsorption measurements indicated that the three compounds became shrunk and amorphous structures after guest removal. Interestingly, single-crystal X-ray diffraction showed that MCF-28 exhibited drastic temperature-induced framework breathing. © 2014 the Partner Organisations.

Wei Yong-Sheng    Ruibiao Lin    Wang Peng    聊培钦    Chunting He    Xue Wei    Lei Hou    Weixiong Zhang    Jiepeng Zhang    陈小明    

CrystEngComm

2014

A record anisotropy barrier (319 cm) for all d-f complexes was observed for a unique Fe-Dy-Fe single-molecule magnet (SMM), which possesses two asymmetric and distorted Fe ions and one quasi-D Dy ion. The frozen magnetization of the Dy ion leads to the decreased Fe relaxation rates evident in the Mössbauer spectrum. Ab initio calculations suggest that tunneling is interrupted effectively thanks to the exchange doublets. A record anisotropy barrier of 319 cm was observed for a Fe-Dy-Fe single-molecule magnet, which possesses two asymmetric and distorted Fe ions and one quasi-D Dy ion. The frozen magnetization of the Dy ions leads to the slowed relaxation of the Fe ions in the Mössbauer spectrum. Ab initio calculations suggest that tunneling is interrupted effectively thanks to the exchange doublets.

刘俊良    Wu Jie-Yi    陈龑骢    Valeriu Mereacre    Annie katherine Powell    Liviu Ungur    Liviu Chibotaru    陈小明     童明良   

Angewandte Chemie - International Edition

2014

A new perovskite-like compound [N(CH)][Cd(N )] is reported here, which undergoes a series of reversible phase transitions including an above-room-temperature ferroelastic phase transition. An order-disorder mechanism is found in these structural transitions owing to the sway of the rod-like N bridges as well as the rotation of the tetrahedron-like [N(CH) ] guests. © 2014 The Royal Society of Chemistry.

Ziyi Du    Zhao Ying-Ping    Weixiong Zhang    Zhou Hao-Long    Chunting He    Xue Wei    Wang Bao-Ying    陈小明    

Chemical Communications

2014