配位化合物中的线性热力学函数关系II.离子选择电极研究α-氨基酸与铜(II)配合物在混合溶剂中的线性热力学函数

用铜离子选择电极测定五种α-氨基酸(对氟苯丙氨酸、丝氨酸、缬氨酸、丙氨酸及α-氨基异丁酸)的铜(Ⅱ)配合物在25.0±0.1、35.0±0.1和45.0±0.1 ℃, μ=0.16 mol L~(-1)KNO_3时于水中及30%(V/V)和50%(V/V)的乙醇-水中的稳定常数. 用pH电位法测定了各配体在混合溶剂中的离解常数. 实验表明用铜离子选择电极研究上述配合物在混合溶剂中的线性自由能、线性焓和线性熵关系, 得到了较好的结果.

Study on the Linear Free Energy Relationships,Linear Enthalpy Relationships and Linear Entropy Relationships of Cu(II)-Aminoacid Coordination Compounds in the Mixed Solvent Using Copper Ion-Selective Electrode

The stability constants of coordination compounds formed from some α-amino acids(αA) DL-P-Fluoro phenylalanine, DL-Serine, DL-Valine, DL-Alanine and α-amino-isobutyric acid with Cu(Ⅱ) were measured by Ion-Selective Electrode at 25±0.1, 35±0.1 and 45±0.1 ℃ in water, 30% ethanol and 50% ethanol solution in the presence of 0. 16 mol·dm~(-3) KNO_3. The order of stability of the Cu(Ⅱ)-αA coordination compounds is in 50% ethanol solution>in 30% ethanol solution>in waterat 35±0.1 ℃. Linear relationships not only existed between the stability of Cu(II)-αA coordination compouds and the base strength of ligands but also existed between the formation enthalpy of coordination compounds and the protonation enthalpy of the ligands, and between the formation entropy of coordination compounds and the protonation entropy of the ligands as well.25—45 ℃ ΔH~...