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Full-Text Articles in Inorganic Chemistry
Mechanism For Copper(Ii)-Mediated Disaggregation Of A Porphyrin J-Aggregate, M. Trapani, I. G. Occhiuto, R. Zagami, G. De Luca, M. A. Castriciano, A. Romeo, L. M. Scolaro, Robert F. Pasternack
Mechanism For Copper(Ii)-Mediated Disaggregation Of A Porphyrin J-Aggregate, M. Trapani, I. G. Occhiuto, R. Zagami, G. De Luca, M. A. Castriciano, A. Romeo, L. M. Scolaro, Robert F. Pasternack
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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 …