Abstract
In this paper, Zn-phthalocyanine (ZnPc) with peripheral mono (ZnPcR1) and tetra quinoleinoxy (ZnPcR4) substituents of the phtalocyanine ring were theoretically studied for the adsorption of NO, CO2, CO, O2 and O3 gases using DFT/B3LYP-D3/6–311++ G (d, p) method. Data displayed a strong interaction between ZnPc, ZnPcR1 and ZnPcR4 and the studied gases. The calculated adsorption energies were -19.509, -13.175, -7.538,-5.359, and -5.280 kcal∙mol-1for ZnPcR4/O3, ZnPcR4/O2, ZnPcR4/CO2, ZnPcR4/NO, and ZnPcR4/CO, respectively. The absorption spectra of the studied complexes were determined using time-dependent density functional theory (TD-DFT). The blue shifted λmax values confirmed the interaction between the complexes and the gases. The electronic properties, geometries, stabilities, noncovalent interactions reduced density gradient (NCI-RDG) and natural population analysis (NPA) have been carried out. FT-IR spectra of all studied complexes displayed a major change in the vibrational frequency and signal strength after gases adsorption. In brief, the optical spectra, the change in the energy gap and the vibrational spectra showed that the studied gases mainly O3 and O2 were very sensitive to ZnPc, ZnPcR1, and ZnPcR4 and hence could be used in sensors.