A Conductometric Study of Complexation Reaction Between Meso-octamethylcalix [4] pyrrole with Titanium Cation in Acetonitrile–Ethanol Binary Mixtures

• Main Authors: Kassim, Anuar, Ahmadzadeh, Saeid, Rezayi, Majid, Rounaghi, Gholam Hossein, Abdollahi, Yadollah
• Format: Article
• Language: English; English
• Published: 2011
• Online Access: http://psasir.upm.edu.my/id/eprint/18781/1/A%20Conductometric%20Study%20of%20Complexation%20Reaction%20Between%20Meso.pdf; http://psasir.upm.edu.my/id/eprint/18781/; http://www.electrochemsci.org/papers/vol6/6104749.pdf
• Institution: Universiti Putra Malaysia

The equilibrium constants and thermodynamic parameters for complexation process between titanium (III) cation and meso-octamethylcalix[4]pyrrole were determined by conductivity measurements in acetonitrile–ethanol (AN–EtOH) binary mixture at different temperatures. The conductance data show that the stoichiometry of the (meso-octamethylcalix[4]pyrrole.[Ti(OH)-(H2O)5])2+ complex in all binary mixed solvents is 1:1[I:M]. The stability of the formed complex is sensitive to the solvent composition and a non-linear behavior was observed for changes of log Kf of this complex versus the composition of the binary mixed solvents. The values of thermodynamic parameters (Hc and Sc) for formation of (meso-octamethylcalix[4]pyrrole.[Ti(OH)-(H2O)5])2+ complex were obtained from temperature dependence of the stability constant using van’t Hoff plots. The obtained results show that the formed complex is enthalpy destabilized, but entropy stabilized and a non-monotonic behavior was observed for variations of standard enthalpy and entropy changes versus the composition of the binary mixed solvents.