Synthesis and QCM gas-sensing properties of 3,4-dialkoxyphenyl tosylamino-substituted phthalocyanines

Octa-substituted metallophthalocyanines [M = Ni(II), Zn(II), Co(II), and Cu(II)] carrying 3,4-dialkoxyphenyl tosylamino groups at the peripheral positions have been synthesized from 1,2-dicyano-4,5-bis[(3,4-diallcoxyplienyl-tosylamino)methyl]benzene in the presence of the corresponding anhydrous metal salt. Next to the metal ion center, the length of the alkyl chains in the dialkoxyphenyl moiety (n = 4, 5, 6, and 12) was varied. In total, sixteen soluble phthalocyanines have been characterized by elemental analysis, FT-IR and H-1-NMR spectroscopy as well as mass spectrometry. Furthermore, the gas sensing properties of these new compounds have been studied using quartz crystal microbalance transducers. The sensing properties are described on the basis of sensor responses to nine different test analytes comprising volatile organic compounds, toxic gases, and chemical warfare agent simulants. The influence of the metal ion center and substituents on sensor selectivity and sensitivity is discussed. The compounds show good performance in the gas-sensing experiments with diverse responses to the analytes. Phthalocyanine species with pronounced selectivity for polar analytes, hydrocarbons or amines have been identified among the set of sensors with the help of multivariate data exploration methods. The results reveal that quite a high diversity in terms of selectivity is introduced through the minute variations to the phthalocyanine structure.