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Controlling flexibility of metal–organic frameworks

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National Science Review 2018年第6期5卷 907-919页

作者： Jie-Peng Zhang Hao-Long zhou dong-dong zhou Pei-Qin Liao Xiao-Ming Chen MOE Key Laboratory of Bioinorganic and Synthetic Chemistry School of ChemistrySun Yat-Sen University Department of Chemistry and Key Laboratory for Preparation and Application of Ordered Structural Materials of Guangdong Province Shantou University

Framework flexibility is one of the most important characteristics of metal–organic frameworks(MOFs),which is not only interesting, but also useful for a variety of applications. Designing, tailoring or controlling framework flexibility of MOFs is much more difficult than for static structural features such as the framework topology and pore size/shape. Nevertheless, with in-depth understanding of the relationship between framework flexibility and the host framework structure, guest loading and other aspects such as the crystal size/morphology and external physical environment, some strategies have been developed for controlling the flexibility of MOFs and the corresponding properties, which are summarized and discussed in this review.

关键词： porous coordination polymers metal–organic frameworks flexibility dynamism adsorption structural transformation

Influence of Chain Architectures on Crystallization Behaviors of PLLA Block in PEG/PLLA Block Copolymers

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Chinese Journal of Polymer Science 2019年第3期37卷 258-267页

作者： Sheng Xiang dong-dong zhou Li-dong Feng Xin-Chao Bian Gao Li Xue-Si Chen Tian-Chang Wang Key Laboratory of Polymer Ecomaterials Changchun Institute of Applied Chemistry Chinese Academy of Sciences Jilin Biomedical Polymers Engineering Laboratory University of Chinese Academy of Sciences South China Advanced Institute for Soft Matter Science and Technology South China University of Technology

The effect of the architecture of poly(ethylene glycol)/poly(L-lactide)(PEG/PLLA) block copolymers on the non-isothermal crystallization behaviors of PLLA blocks was investigated by differential scanning calorimetry(DSC) and wide angle X-ray diffraction(WAXD). 1-Arm MPEG-b-PLLA and 4-arm PEG-b-PLLA(4PEG-b-PLLA) were synthesized by the ring-opening polymerization of Llactide in the presence of poly(ethylene glycol) methyl ether(MPEG) and 4-arm poly(ethylene glycol)(4PEG). 4-Arm PLLA-b-MPEG(4PLLA-b-PEG) was synthesized by coupling 4-arm PLLA and MPEG. The WAXD results indicated that the crystalline structure of PLLA blocks did not alter due to the different chain architectures. The average values of Avrami index(ˉn) were all above 4, which indicated that the nucleation mechanism of PLLA blocks was heterogeneous nucleation, regardless of the architectures. The overall crystallization rates were decreased markedly as following: MPEG-b-PLLA > 4PEG-b-PLLA > 4PLLA-b-PEG, ascribed to the different confinement by PEG blocks and to the steric hindrance of chain architectures. Therefore, the crystallization of PLLA blocks became more difficult and the crystallization activation energy of the PLLA blocks increased due to the confinement of chain architectures.

关键词： Poly(L-lactide) Poly(ethylene glycol)/poly(L-lactide)block copolymer Non-isothermal crystallization Chain architecture

Research on the novel asymmetric frequency division duplex technique

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The Journal of China Universities of Posts and Telecommunications 2006年第4期13卷 13-18页

作者： ZHANG Ying-hai WANG Wei-dong dong Yu zhou Kai-Jie Information and Electronics Technology Laboratory Beijing University of Posts and Telecommunications Beijing 100876 China

This article introduces a novel duplex transmission technique-asymmetric frequency division duplex （AFDD）. One of the characteristics in future mobile systems is asymmetric characteristic caused by service requirement and electromagnetic radiation, AFDD is designed to adapt to the new asymmetric characteristics. The AFDD puts forward a novel adaptive frequency-allocation scheme in downlink and uplink. Combining AFDD with code division multiple access （CDMA） communication system, it is proven that AFDD improves the capacity and coverage of the system compare with FDD CDMA system.

关键词： asymmetric characteristics AFDD Duplex Mobile communications

A partially fluorinated ligand for two super-hydrophobic porous coordination polymers with classic structures and increased porosities

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National Science Review 2021年第3期8卷 99-107页

作者： Chao Wang dong-dong zhou You-Wei Gan Xue-Wen Zhang Zi-Ming Ye Jie-Peng Zhang MOE Key Laboratory of Bioinorganic and Synthetic Chemistry School of ChemistrySun Yat-Sen University

3-Ethyl-5-trifluoromethyl-1,2,4-triazole is synthesized by a one-pot *** this asymmetric triazole ligand bearing one trifluoromethyl and one ethyl as side groups,we construct two new porous coordination polymers,MAF-9 and MAF-2 F,being isostructural with the classic hydrophobic and flexible materials,FMOF-1 and MAF-2,based on symmetric triazole ligands bearing two trifluoromethyl groups or two ethyl groups,***-9 and MAF-2 F can adsorb large amounts of organic solvents but completely exclude water,showing superhydrophobicity with water contact angles of 1520 in between those of FMOF-1 and ***-9 exhibits very large N2-induced breathing and colossal positive and negative thermal expansions like FMOF-1,but the lower molecular weight and smaller volume of MAF-9 give 16%and 4% higher gravimetric and volumetric N2uptakes,*** contrast,MAF-2 F is quite rigid and does not show the inversed temperature-dependent N2adsorption and large guest-induced expansion like ***,despite the higher molecular weight and larger volume,MAF-2 F possesses 6% and 25%higher gravimetric and volumetric CO2uptakes,*** results can be explained by the different pore sizes and side group arrangements in the two classic framework prototypes,which demonstrate the delicate roles of ligand side groups in controlling porosity,surface characteristic and flexibility.

关键词： porous coordination polymers metal-organic frameworks super-hydrophobicity flexibility

A kinematic study of the integral shaped filament:what roles do filaments play in forming young stellar clusters?

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Research in Astronomy and Astrophysics 2018年第7期18卷 37-44页

作者： Gang Wu Esimbek Jarken Willem Baan Jian-Jun zhou dong-dong zhou Xiao-Hong Han Aldiyar Agishev Xinjiang Astronomical Observatory Chinese Academy of SciencesUrumuqi 830011China Key Laboratory of Radio Astronomy Chinese Academy of SciencesUrumqi 830011China University of Chinese Academy of Sciences Beijing 100049China Netherlands Institute for Radio Astronomy NL-7991 PD Dwingeloothe Netherlands Faculty of Physics and Technology A1-Farabi Kazakh National UniversityAlmaty050049Kazakhstan

Young protoclusters （embedded stellar clusters） are responsible for the vast majority of star formation currently occurring in the Galaxy. Recent observations suggest a scenario in which filamen-tary structures in the interstellar medium represent the first step towards precluster clumps and even- tually star formation. Whether filaments continuously fuel the star formation process when the cluster accretes material is still an open question. In this paper, we present a case study of the famous ＇integral shaped filament＇（ISF） in the Orion A molecular cloud and we seek to study the kinematics which is truly originated from the ISF. We firstly define the central ridge of the ISF with NHa, ^12CO, ^13CO and N2H^＋. Undulations are present in all the ridges. Moreover, a large scale offset is apparent in the ridges as derived by different tracers, which may be explained by the slingshot mechanism proposed by Stutz ＆ Gould. We fit the velocity field of the ISF and find the derived velocity gradient is about 0.7 km s^- 1 pc^- 1 which may come from an overall contraction. We propose a method to check the accretion flow along the ISF by using the velocity deviations of different molecular tracers, which is better than the common method of using the velocity distribution of one tracer alone. Using the velocity deviations, we also find that OMC-1 to 5 are located close to the local extrema of the fluctuations, which may demonstrate that gas flows toward each clump along the ISE

关键词： ISM clouds - ISM structure - ISM kinematics and dynamics - stars formation

A topology approach to overcome the pore size/volume trade-offs for autonomous indoor humidity control

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Science China Chemistry 2024年第9期67卷 2968-2974页

作者： Zhi-Shuo Wang Xue-Wen Zhang Kai Zheng Xiao-Xian Chen dong-dong zhou Jie-Peng Zhang MOE Key Laboratory of Bioinorganic and Synthetic Chemistry GBRCE for Functional Molecular EngineeringSchool of ChemistryIGCMESun Yat-Sen UniversityGuangzhou 510275China Chemistry and Chemical Engineering Guangdong Laboratory Shantou 515021China

Autonomous indoor humidity control is gaining more and more attention but is limited by the trade-offs among pore volume,pore size and water stability of water *** solve this problem by using a unique coordination network topology combined with hydrolytically stable M(Ⅲ)carboxylate *** extending the ligand length from 9.0 to 11.2 and 13.7?,the pore volume significantly increases from 0.99 to 1.40 and 1.78 cm^(3)g^(-1),which proportionally increases the saturated water adsorption ***,the pore size slightly increases from 10.4 to 11.0 and 13.5A,which restricts the isotherm inflection pressure and hysteresis width to meet the requirement of indoor humidity *** single-crystals suitable for Xray diffraction studies were obtained by using Fe(Ⅲ)salts,while isostructural frameworks with sufficiently high water stabilities were synthesized by using Cr(Ⅲ)salts,which offer record working capacity of 0.90 and 1.10 g g^(-1)for indoor humidity control.

关键词： metal-organic frameworks water adsorption indoor humidity control water stability pore engineering

Solvent-Controlled Construction of Molecular Chains and Bowls/Sieves from a Bent Dipyridyl Ligand

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Chinese Journal of Chemistry 2021年第9期39卷 2523-2528页

作者： Xiao-Yun Tian Xiao-Xian Chen Chao Wang Zi-Ming Ye dong-dong zhou Jie-Peng Zhang MOE Key Laboratory of Bioinorganic and Synthetic Chemistry School of ChemistrySun Yat-Sen UniversityGuangzhouGuangdong 510275China

Solvothermal reactions of 3,6-di(pyridin-4-yl)-9H-carbazole(dpc)with Cu(ll)yielded crystals of two new coordination complexes,namely[Cu(CH_(3)COO)_(2)(dpc)(H_(2)O)_(2)]n-xGuest(1)and[Cu_(13)(HCOO)_(16)(dpc)16(H_(2)O)6](HCOO)10-Guest(2),in which CH_(3)COO_and HCOO-were generated from the hydrolysis of the solvents A/zAZ-dimethylacetamide(DMA)and A/zA/-dimethylformamide(DMF),***-crystal X-ray diffraction showed that 1 possesses simple wavy coordination chains,while 2 possesses large molecular bowls/sieves with outer and inner effective sizes of 30.2 × 30.2 × 25.5 A^(3) and 15.0 × 15.0 × 18.6 A^(3),respectively,which consists of 4 linear Cu_(3)(HCOO)_(4)(H_(2)O)clusters and 12 dpc ligands as the square-shaped wall and a claw-like Cu(dpc)_(4) fragment as the ***-free 2 can adsorb considerable amounts of CO_(2)/H_(2)O and CH_(3)OH but completely exclude C2H4 and C3H6z which shows a potential application for olefin drying.

关键词： Self-assembly Crystal engineering Microporous materials Molecular sieve Olefin drying

A novel pillared-layer-type porous coordination polymer featuring three-dimensional pore system and high methane storage capacity

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Science China Chemistry 2016年第8期59卷 970-974页

作者： Jiao-Min Lin Chun-Ting He Pei-Qin Liao dong-dong zhou Jie-Peng Zhang Xiao-Ming Chen Key Laboratory of Bioinorganic and Synthetic Chemistry Ministry of EducationSchool of Chemistry and Chemical Engineering Sun Yat-Sen University Guangzhou 510275 China

Solvothermal reaction of Zn（NO3）2, 4-（1H-pyrazol-4-yl）pyridine （Hpypz） and 1,3,5-benzenetricarboxylic acid （H3btc） in N,N-dimethylacetamide （DMA） produced a new porous coordination polymer [Zns（pypz）4（btc）2] （1）. Single-crystal X-ray diffraction study of 1 showed that deprotonated pypz^- ligands served as 1,2,4-triazolate-like ligands, linking Zn（II） ^＋ ions to form porous two-dimensional （2-D） sql-a layers {Zn（pypz）} , which were further connected by eight-legged pillars {Zn2（btc）4（H2O）2}8- based on the typical paddlewheel dinuclear Zn2（RCOO）4（H20）2 cluster to form a novel type of non-interpenetrated pillared-layer framework with 3-D intersecting pore system and large pore volume. Gas sorption measurements revealed that 1 possesses large BET surface area of 2061 m^2g^-1 and very high methane total uptake of 245 cm^3（STP） cm^-3 at 298 K and 65 bar.

关键词： metal-organic framework network topology eight-legged pillar methane storage

Multistep evolution from a metal–organic framework to ultrathin nanosheets

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Science Bulletin 2019年第14期64卷 964-967页

作者： Yun Li Jin Huang Zong-Wen Mo Xue-Wen Zhang Xiao-Ning Cheng Li Gong dong-dong zhou Jie-Peng Zhang MOE Key Laboratory of Bioinorganic and Synthetic Chemistry School of Chemistry Sun Yat-Sen University Guangzhou 510275 China Instrumental Analysis and Research Center Sun Yat-Sen University Guangzhou 510275 China

Two-dimensional (2D) materials and ultrathin nanosheets have attracted tremendous research interests [1-4]. Exfoliation of porous coordination polymers (PCPs) or metal-organic frameworks (MOFs) with 2D coordination structures is emerging as a viable strategy for preparation of new types of 2D materials [5-8]. The relatively weak bonding within and strong interactions between 2D coordination networks are the main problems for successful exfoliation [9]. Pretreatments of the layered MOFs to expand the interlayer distances can be helpful [10-12]. Capturing the exfoliation intermediates and visualizing their structures are valuable for understanding the exfoliation mechanism and confirming the structures of the final 2D materials [11,12].

关键词： Two-dimensional (2D) porous coordination polymers (PCPs) metal-organic frameworks (MOFs)