First-principles design of a Mg-porphyrin nanoring sensor via dipole moment and dispersion energy engineering for high-sensitivity detection of hazardous industrial gases.

This study employs density functional theory (DFT) with Grimme's D3-BJ dispersion correction to investigate the adsorption of six hazardous industrial gases (HIGas) including cyanogen chloride (CNCl), formaldehyde (CH2O), cyanogen (C2N2), hydrogen cyanide (HCN), dichloroacetylene (C2Cl2), and phosgene (COCl2) on a magnesium-porphyrin nanoring sensor (NR4P4Mg4). The interactions are characterized as physical and reversible, with BSSE corrected adsorption energies ranging from -1.90 to -18.36 kcal/mol. Gas adsorption induces a significant band gap increase of approximately 122 %, substantially reducing electrical conductivity, while maintaining adsorption distances of 2.16-3.09 Å consistent with physisorption. The calculated recovery times spanning picoseconds to microseconds indicate rapid adsorption-desorption cycles. Electronic structure analysis through Natural Bond Orbital (NBO) and Frontier Molecular Orbital (FMO) calculations reveals consistent electron transfer from gas molecule HOMOs to the nanoring's LUMO. The presence of four distinct adsorption sites enables saturation-free detection of HIGas, with demonstrated resilience against atmospheric interference from nitrogen and humidity.