Thin films of poly(oxyethylene)-substituted phthalocyaninato zinc(II) and oxotitanium(IV) complexes: synthesis, structure and sensor response to ammonia

In this work, the effect of chloro-substitution in poly(oxyethylene)-substituted phthalocyaninato zinc(II) and oxotitanium(IV) complexes on the ordering and sensor response of their thin films to ammonia was studied. Thin films of thia-bridged tetrapoly(oxyethylene)- and tetrachlorotetrapoly(oxyethylene)-substituted zinc and titanyl Pcs forming mesophases in wide temperature range were spun onto glass slides with interdigitated electrodes to test their chemiresistive sensor response to ammonia in the concentration range from 1 to 50 ppm. It was shown by the methods of UV–Vis, polarized Raman spectroscopy and polarized optical microscopy that these phthalocyanines formed thin films with different orientation and ordering in dependence on their molecular structure. The introduction of chloride substituents into the phthalocyanine ring was found to lead to the increase of the chemiresistive sensor response of both zinc and oxotitanium phthalocyanine films toward low concentrations of ammonia in air.