摘要
本文研究了4种多取代铁卟啉在三氯甲烷溶剂中与咪唑(Im)、四甲基咪唑(4-MeIm)以及四甲基吡啶(4-MePy)3种含氮碱的轴向配位反应,采用微量光谱滴定法,测定了不同温度(283~308K)下的配位反应平衡常数(logβn)以及标准摩尔焓变(ΔrHm^θ)、标准摩尔熵变(ΔrSm^θ)和标准摩尔吉布斯自由能变(ΔrGm^θ)等热力学常数。结果表明,在给定的实验条件下,每种铁卟啉均可以与含氮碱反应生成稳定的含有一个或两个轴向含氮碱配体的配合物,卟啉大环上的取代基以及含氮碱的种类对轴向配体的数目及反应平衡常数的大小具有较大的影响。铁卟啉与含氮碱的轴向配位反应均为自发的放热反应,降低体系的温度有利于生成稳定的轴向配合物。
The axial coordination reactions of four polysubstituted iron porphyrins with three nitrogenous bases including imidazole(Im),4-methylimidazole(4-MeIm),and 4-methylpyridine(4-MePy)were studied in CHCl3.The equilibrium constants(logβn)and thermodynamic constants(ΔrHm^θ,ΔrSm^θ andΔrGm^θ)of the axial coordinate reactions were determined at different temperature(283-308 K)using a micro-spectral titration method.The results indicate that each iron porphyrin can react with the nitrogenous base to form a stable complex containing one or two axial ligands under the given experimental conditions.The substituents on porphyrin macrocycle and the structure of nitrogenous bases have significant effect on the number of axial ligands and magnitude of the reaction equilibrium constants.The coordination reactions of iron porphyrins with the nitrogenous bases are of the spontaneous exothermic reactions and decreasing the temperature might be in favor of generating axial coordinated complexes.
作者
侯月平
王丽萍
房媛媛
黄广凤
欧忠平
HOU Yue-ping;WANG Li-ping;FANG Yuan-yuan;HUANG Guang-feng;OU Zhong-ping(Department of Chemical Engineering,Zhenjiang Vocational Technical College,Zhenjiang 212003;School of Chemistry and Chemical Engineering,Jiangsu University,Zhenjiang 212013)
出处
《分析科学学报》
CAS
CSCD
北大核心
2019年第4期428-432,共5页
Journal of Analytical Science
基金
国家自然科学基金(No.21501070)
江苏大学高级人才基金(No.05JDG051,15JDG131)
关键词
多取代铁卟啉
光谱滴定
轴向配位反应
平衡常数
热力学常数
Polysubstituted iron porphyrins
Spectral titration
Axial coordination reactions
Equilibrium constants
Thermodynamic constants
