| Summary: | 碩士 === 國立臺灣科技大學 === 化學工程系 === 90 === In this study, we utilized piezoelectric quartz crystal microbalance (QCM) to detect volatile organic components (VOC) with substituted metal phthalocyanine (SMPc) thin film sensors. The effects of central metal, and acid-base interaction and steric effect of substituents were investigated. Experiments consist of five parts︰
(1)Four substituted CuPc︰Different substituents cause different packing density, especially when a large side chain group is at the ortho-position, the aromatic ring of the phenoxy moiety rotates out of the plane of the main SMPc ring structure, thus causes lower packing density and higher gas sensitivity.
(2)Four substituted H2Pc (SPc)︰H2Pc, without any side chain substituents, its molecules pack tightly and makes gas diffusion more difficult, has lowest gas adsorptivity; The substitution groups of (Oct)H2Pc cause looser packing and more adsorption sites, but the steric hindrance effect of butoxy group prevent the gas molecules to interact with the π electron system of the phthalocyanine, cause the gas sensitivity in the middle; And (t-Bu)H2Pc, with loose packing due to the substitution group and no steric hindrance from the tert-butyl group, possesses the highest VOC sensitivity among the three.
(3)Substituted naphthalocyanines (SNc)︰The four additional aromatic rings of SNc, as compared to SPc, would enhance π-π and CH-π interactions, so SNc has higher VOC sensitivity than SPc.
(4)Effect of central metal atom in SMPc︰ Certain central metal atom (e.g. Zn) could destroy the planar structure of phthalocyanine, and increase the electron density of the outer N atoms, thus enhance its ability to form hydrogen bonding with polar VOC molecules.
(5)Lewis acid-base interaction︰ Due to the unshared electrons pairs in N atoms, the sensing sensitivity of phthalocyanines towards acid molecule is much higher than other VOC.
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