Triazolephthalocyanine versus phthalocyanine nickel(ii) and copper(ii) complexes: a thermogravimetric stability study

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Abstract
Several nickel(II) and copper(II) complexes of triazolephthalocyanine and phthalocyanine, bearing different substituents and substitution patterns, have been synthesised and studied by standard thermogravimetric techniques in order to evaluate their thermal stability and related molecular parameters. The overall thermodegradation processes have been analysed in the partial degradation processes. The comparison of thermal stability has been made in terms of partial degradation fitting parameters: maximum degradation rate (Rmax), maximum degradation rate temperature (TRmax), degradation temperature range which is related to the half-width at half-height values (Γ); and conventional kinetic parameters: activation energy (Ea), pre-exponential factor (ln A) and reaction order (n); obtained by Barrett methods. The Ni(II) and Cu(II) phthalocyanine and triazolephthalocyanine complexes display high thermostability. The degradation processes and the corresponding maximum degradation rate temperature depend upon the complexed metal and the number, nature and position of the peripheral groups. The replacement of nickel by copper in unsubstituted metallophthalocyanines increases the degradation temperature, while the same change in triazolephthalocyanine complexes decreases this temperature. The effect of the side group and the kinetic behaviour have been studied. The compensation effect between pre-exponential factor A and activation energy Ea is confirmed.
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