Optical absorption spectroscopy investigation on the interaction of tetra (methyl pyridinum -4-yl) porphyrin (TMPyP) and its copper(Ⅱ) complex (CuTMPyP) with 2,4,6-trinitrotoluene (TNT) in acetonitrile

摘要

Interaction of two cationic porphyrins, 5, 10, 15, 20-tetra (Methyl pyridinum -4-yl) Porphyrin (TMPyP) and its Cu (Ⅱ) complex (CuTMPyP), with TNT in acetonitrile has been studied by UV-Vis spectroscopy. Analysis of the spectral data revealed formation of a 1:1 conjugate between cationic porphyrins and TNT. The binding constants (K_n) of this conjugation have been obtained at various temperatures through evaluation of absorption data. The binding constants of TNT to TMPyP and CuTMPyP were decreased with increasing temperature in acetonitrile. The thermodynamic parameters of the process, including entropy and enthalpy changes, have been calculated by means of van't Hoff plots method. The results showed that the TNT binding process for both porphyrins is an enthalpy driven phenomenon.