物理化学学报 >> 2003, Vol. 19 >> Issue (05): 445-449.doi: 10.3866/PKU.WHXB20030514

研究论文 上一篇    下一篇

稀土钬丙氨酸配合物的热力学性质

刘北平;谭志诚;余华光;兰孝征;张大顺;刘平;孙立贤   

  1. 常德师范学院化学系，常德　415000；中国科学院大连化学物理研究所热化学实验室，大连　116023
  • 收稿日期:2002-10-21 修回日期:2003-01-13 发布日期:2003-05-15
  • 通讯作者: 谭志诚 E-mail:tzc@dicp.ac.cn

Thermodynamic Properties of [Ho2(Ala)4(H2O)8]Cl6 (Ala=alanine)

Liu Bei-Ping;Tan Zhi-Cheng;Yu Hua-Guang;Lan Xiao-Zheng;Zhang Da-Shun;Liu Ping;Sun Li-Xian   

  1. Department of Chemistry, Changde Normal College, Changde　415000; Thermochemistry Laboratory, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian　110623
  • Received:2002-10-21 Revised:2003-01-13 Published:2003-05-15
  • Contact: Tan Zhi-Cheng E-mail:tzc@dicp.ac.cn

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摘要： 合成了稀土氯化钬丙氨酸配合物，[Ho2(Ala)4(H2O)8]Cl6，的晶体.用绝热量热法测定了其在78～363 K温区的热容.在214～255 K温区发现一固－固相变，相变峰温、相变焓和相变熵分别为235.09 K，3.017 kJ•mol－1和12.83 J•K－1•mol－1.用最小二乘法将实验热容值拟合成热容随温度变化的多项式方程,利用此方程式和热力学函数关系,计算出以298.15 K为参考温度的热力学函数值.在40～800 ℃温区，用热重分析和差示扫描量热法研究了该配合物的热稳定性，观察到[Ho2(Ala)4(H2O)8]Cl6分两步分解，第一步从80 ℃开始，179 ℃结束；第二步从242 ℃开始，479 ℃结束.从热分析结果推测出该配合物可能的热分解机理.

关键词: 稀土氨基酸配合物, 氯化钬丙氨酸配合物（[Ho2(Ala)4(H2O)8]Cl6）, 绝热量热, 热容, 热力学函数, 热重, 差示扫描量热

Abstract: The crystalline complex of holmium chloride with alanine, [Ho2(Ala)4(H2O)8]Cl6,was synthesized. Heat capacities of [Ho2(Ala)4(H2O)8]Cl6 were measured by adiabatic calorimetry over the temperature range from 78 to 363 K. A solid-solid phase transition was found between 214 K and 255 K with the peak temperature of 235.09 K. The enthalpy and entropy of the transition were determined to be 3.017 kJ•mol－1 and 12.83 J•K－1•mol－1,respectively.The molar heat capacities were presented by a fitted polynomial as a function of reduced temperature. The thermodynamic functions relative to the reference temperature 298.15 K were calculated based on the heat capacity data. Thermal stability of the complex was studied by thermogravimetry (TG) and differential scanning calorimetry (DSC) over the temperature range from 40 to 800 ℃.From the DTG curves, two peaks were observed in the process of the thermal decompositions for the complex. The first mass-loss peak started from 80 ℃ and ended at 179 ℃,and the second mass-loss peak started from 242 ℃ and ended at 479 ℃.A possible mechanism of the thermal decomposition was presented.

Key words: Complex of rare earth with amino acid, [Ho2(Ala)4(H2O)8]Cl6, Adiabatic calorimetry, Heat capacity, Thermodynamic function, 　Thermogravimetry, Differential scanning calorimetry