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Thermal Degradation And Solid State Electrical Conductivity Study Of Phenothiazinium Picrates

B.N.Achar, M.A.Ashok

Temperature dependent electrical conductivity and thermal degradation kinetics of charge transfer complexes of phenothiazine derivatives namely promethazinium picrate(PP), dioxo promethazinium picrate(DPP), promazinium picrate(PMP) and chlorpromazinium picrate(CPP) are reported. The activation energies are calculated based on their electrical conductivity studies conducted over the temperature range 30-1750C. These energies for promethazinium, dioxo promethazinium, promazinium and chlorpromazinium picrates are found to be 0.19, 0.52, 0.17 and 1.29eV respectively. DPP and PMP exhibited semiconducting behavior whereas PP and CPP showed both metallic and semiconducting behaviors. Single crystal X-ray data of PMP and CPP are presented. The materials are analyzed for the kinetic parameters like the activation energy for decomposition and the Arrhenious pre-exponential factors in their pyrolysis region using BroidoÂ’s, Coats- Redfern and Horowitz-Metzger methods. Using these factors and the standard equations thermodynamic parameters such as enthalpy, entropy and free energies are calculated. Thermogravimetric study on these phenothazine picrate derivatives in air indicated that they are thermally stable up to1000C.