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| Phase Transitions of Two Coordination Polymers [MCl2(β-ala)]n (M=Co, Ni; β-ala=3-Aminopropionic Acid) |
| Author Name | Affiliation | E-mail | | SU Yu-Jun | School of Chemistry, Sun Yat-Sen University, Guangzhou 510275, China | | | XU Ke | School of Chemistry, Sun Yat-Sen University, Guangzhou 510275, China | | | YUAN Wei | School of Chemistry, Sun Yat-Sen University, Guangzhou 510275, China | | | HUANG Rui-Kang | School of Chemistry, Sun Yat-Sen University, Guangzhou 510275, China | | | ZHANG Wei-Xiong | School of Chemistry, Sun Yat-Sen University, Guangzhou 510275, China | zhangwx6@mail.sysu.edu.cn | | CHEN Xiao-Ming | School of Chemistry, Sun Yat-Sen University, Guangzhou 510275, China | cxm@mail.sysu.edu.cn |
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| Abstract: 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 (Tc-heating, Tc-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. |
| Keywords: coordination polymer structural phase transition order-disorder phase transition dielectric anomaly |
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| SU Yu-Jun,XU Ke,YUAN Wei,HUANG Rui-Kang,ZHANG Wei-Xiong,CHEN Xiao-Ming.Phase Transitions of Two Coordination Polymers [MCl2(β-ala)]n (M=Co, Ni; β-ala=3-Aminopropionic Acid)[J].Chinese Journal of Inorganic Chemistry,2017,33(11):2005-2010. |
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