Spectrophotometric study of interaction of iodine with 4′-aminobenzo-15-crown-5 in chloroform, dichloromethane and 1,2-dichloroethane solutions

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• 作者：Masoumeh Hasani ; Sakineh Akbari
• 关键词：4′ ; -Aminobenzo-15-crown-5 ; Iodine ; Charge transfer complex ; Spectrophotometry ; Kinetic ; Crown ether
• 刊名：Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy
• 出版年：2007
• 出版时间：November 2007
• 年：2007
• 卷：68
• 期：3
• 页码：409-413
• 全文大小：195 K

文摘

The formation of charge transfer complex between 4′-aminobenzo-15-crown-5 (AB15C5) and iodine is investigated spectrophotometrically in chloroform, dichloromethane (DCM) and 1,2-dichloroethane (DCE) solutions at 25 °C. The continuous variation method clearly revealed the formation of 1:1 charge transfer complex in solution. The observed time dependence of the charge transfer band and subsequent formation of I₃⁻ in solution were related to the slow transformation of the initially formed 1:1 AB15C5·I₂outer complex to an inner electron donor–acceptor (EDA) complex, followed by fast reaction of the inner complex with iodine to form a triiodide ion. The pseudo-first-order rate constants for the transformation process were evaluated from the absorbance–time data and found to vary in the order of 1,2-DCE > DCM > CHCl₃. The values of the formation constant, K_DA, for each complex are evaluated from Benesi–Hilebrand equation. Stability of the resulting complex in three solvents was also found to vary in the order of 1,2-DCE > DCM > CHCl₃.