Synthesis, characterization and gas sensing properties of novel homo and hetero dinuclear ball-type phthalocyanines

New ball-type homodinuclear Co(ii)-Co(ii) phthalocyanine (2) and ball-type heterodinuclear Co(ii)-Fe(ii) phthalocyanine (3) were synthesized from the corresponding [2,10,16,24-tetrakis{4,4′-cyclohexylidenebis(2-cyclohexyphenoxyphthalonitrile)}phthalocyaninatocobalt(ii)] (1). The novel compounds have been characterized by elemental analysis, IR, UV-Vis and MALDI-TOF mass spectroscopy. Gas sensing capability of the spin coated film of 2 and 3 were studied using amperometric technique at various temperatures. For a better understanding of the interaction of 2 and 3 films with organic compounds, two different groups of compounds (aromatics and alcohols) were selected as test analytes. It was observed that the operating temperature had a considerable effect on the gas sensing performance of the sensors investigated. The experimental results show that 3 film offers a promising perspective as a sensing material for the detection of relatively low aromatic vapours even at room temperature. This suggests that aromatics might be distinguished from alcohols. The obtained data were analysed using two different adsorption kinetic models: the pseudo first order equation and Elovich equation to determine the best fit equation for the adsorption of toluene vapor onto 2 and 3 films. The first-order equation was the best of the various kinetic models studied to describe the adsorption kinetic of toluene on Pc films at higher concentrations, as evidenced by the highest correlation coefficients. In addition, it was observed that Elovich equation generates a straight line that best fit to the data of adsorption of lower concentrations of toluene.