金属离子与卟啉的嵌入反应动力学研究 IV.Cu(Ⅱ)T_(β-N-EAES)PyP^(4+)生成反应中的动力学盐效应

Studies on Kinetics of Incorporation of Metal Ion into Porphyrin Ⅳ. Kinetic Salt Effect in Formation Reaction of Cu (Ⅱ) T_(β-N-EAES)PyP^(4+)

在不同离子强度的高氯酸钠水溶液中,用分光光度法测量自由卟啉H_2T_(β-N-EAES)PyPBr_4(简记为H_2P^(4+))与Gu(Ⅱ)离子的配位反应动力学,探讨高氯酸钠对Cu(Ⅱ)离子嵌入自由卟啉反应的催化本质.在给定条件下,高氯酸根与自由卟啉的缔合数n为1;缔合平衡常数K_0=3.70±0.42dm^3.mol^(-1).配位反应实验动力学方程为d[Cu(Ⅱ)P^(4+)]/dt=5.55×10~5γCu^2+γH_2P^4+γ(3)[ClO_4^-]~3[Cu^(2+)][H_2P]_总/(1.00+10^(2.02{H+}+10^(4.36{H^+}^2)、反应的活化能E=53.30kJ·mol^(-1),活化焓变△H~ =50.31kJ·mol^(-1),活化熵变△S~ =-77.65J·mol^(-1)·K^(-1).提出了金属卟啉生成反应中的ClO_4^-催化卟啉环变形的反应机理.

Kinetics of reaction of Cu(II) ion incorporating into tetrakis (N-carboethoxymethyl-3-pyridyl) Porphyrin bromide (H_2T_(β-N-EAES)PyPBr_4) was studied in different concentration solution of NaclO_4 spectrophotomertrically. Catalysis of NaClO_4 was proved for the reaction. Equilibrium constant of association reaction of H_2T_(β-N-EAES) PyPBr_4 with ClO_1^- ion was found (K_0=3.70±0.42dm^3·mol^(-1)), Association number (n) of ClO_4^- ion with the porphyrin was determined (n=1).Experiment kinetic equation is expressed as d[Cu(II)P^(4+)]/dt=5.55×10~5γ_(cu^(2+))γ_(H_2P^(4+)γ_((ClO_4^-)~3[ClO_4^-]~3[Cu^(2+)] [H_2P]_(total)/(1.00+10^(2.02){H^+}+10^(4.36){H^+}~2). Enthalpy production of activation of the reaction is ⊿H^+=50.31kJ·mol^(-1). Energy of activation of the reaction is E=53.30kJ· mol^(-1).Entropy production of activation of the reaction is ⊿S~≠=-77.65J·mol^(-1)·K^(-1). Reaction mechanism of the deformation of the porphyrin ring was proposed for metal ion incorporation by catalysis of ClO_4^- ion.