Gas sensing behavior of metal-phthalocyanines: Effects of electronic structure on sensitivity

Cu-phthalocyanine (CuPc) and five of its metal variants (M = Mg, Mn, Co, Ni, and Zn) have been studied by density functional theory (DFT) methods for sensing five volatile organic compounds - isoprene, acetone, ammonia, methanol, and methane. Having performed experimental validation of the methods, interaction energies, binding configurations, changes in charge distributions and energy levels after interaction, and interaction barriers were studied to account for the sensitivity trend across the analytes for CuPc, while also providing supporting data from experiments carried out herein. It is also demonstrated that relatively simple calculations of interaction barrier can result in quick screening of metal-Pc variants for an analyte without any extensive experimental or computational efforts. Present literature lacks such detailed studies for these materials and analytes. Thus, this work would consolidate the understanding of sensing phenomena at the electronic structure level that could be useful for emerging technologies in gas sensing.