卟啉
铜
化学
金属
动力学
离子强度
离子
单体
无机化学
离子键合
光化学
物理化学
有机化学
水溶液
物理
量子力学
聚合物
作者
Mariachiara Trapani,Ilaria Occhiuto,Roberto Zagami,Giovanna De Luca,Maria Angela Castriciano,Andrea Romeo,Luigi Monsù Scolaro,Robert F. Pasternack
出处
期刊:ACS omega
[American Chemical Society]
日期:2018-12-31
卷期号:3 (12): 18843-18848
被引量:12
标识
DOI:10.1021/acsomega.8b02913
摘要
J-aggregates of anionic meso-tetrakis(4-sulfonatophenyl)porphyrin form at intermediate pH (2.3–3.1) in the presence of NiSO4 or ZnSO4 (ionic strength, I.S. = 3.2 M). These aggregates convert to monomeric porphyrin units via metallation with copper(II) ions. The kinetics for the disassembly process, as monitored by UV/vis spectroscopy, exhibits zeroth-order behavior. The observed zeroth-order rate constants show a two-term dependence on copper(II) ion concentrations: linear and second order. Also observed is an inverse dependence on hydrogen ion concentration. Activation parameters have been determined for the disassembly process leading to ΔH≠ = (+163 ± 15) kJ·mol–1 and ΔS≠ = (+136 ± 11) J·K–1. A mechanism is proposed in which copper(II) cation is in pre-equilibrium with a reactive site at the rim of the J-aggregate. An intermediate copper species is thus formed that eventually leads to the final metallated porphyrin either through an assisted attack of a second metal ion or through a direct insertion of the metal cation into the macrocycle core.
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