Sensing alcohol vapours with novel unsymmetrically substituted metallophthalocyanines
Unsymmetrically substituted phthalocyanines were synthesized with the well-known statistical condensation method, by using two differently substituted precursors, 4-tert-butylphthalonitrile and 4-(4-pyrrol-1-yl)phenoxyphthalonitrile. Spin coated thin films of these compounds have subsequently exposed to the varying concentrations of methanol, ethanol and butanol between 25 and 150 ppm in order to investigate the effect of the number of the carbon atom in alcohol vapors. Results from this preliminary investigation indicated that the sensor performance parameters such as sensitivity, response and recovery times strongly depend on the number of the carbon atom in analyte molecules. It was found that the sensitivity of the sensors decreases with increasing number of the carbon atom. Electrochemistry of CoPc and MnClPc were carried out with cyclic and square wave voltammetry methods. Both complexes illustrated metal and ring based electron transfer reactions. While CoPc gave only one metal based reduction ([CoIIPc2-]/[CoIPc2-]1-), two metal based reductions ([Cl-MnIIIPc2-] / [Cl-MnIIPc2-]1- and [Cl-MnIIPc2-]1- / [Cl-MnIPc2-]2-) were observed with MnPc. Color changes during the in situ spectroelectrochemical measurements illustrated their versatility for display technologies. Pyrrole containing substituents of the complexes triggered their electropolymerization on the working electrode, which enhance their worthy as functional materials for modified electrodes.