Investigation of the sensing behavior of C4N3 for the detection of Benz[a]anthracene, chrysene, and chlorinated organic pollutants: A computational study.

Persistent organic compounds, also known as "forever chemicals", present serious risk to both the human and environmental health because of their enduring stability, bioaccumulation, and long-range mobility. This study evaluates the capability of C4N3 as a sensitive and selective detecting nanomaterial for the sensing of POPs, utilizing DFT (density functional theory). Adsorption energies of benz[a]anthracene (BA), chrysene (CR), 3,3',4,4'-tetrachlorobiphenyl (TP), and 3,3',4,4'-tetrachlorodiphenyl ether (TD) on C4N3 were calculated, giving moderate values of -21.15, -7.0, -15.09, and -19.27 kJ/mol, respectively. The adsorption-energies reveal the weak van-der Waals forces, further supported by the results of quantum-theory of atoms-in-molecules analysis and non-covalent interaction analysis. Mild bonding interactions between the C4N3 surface and BA, CR, TP, & TD molecules can lead to enhanced selectivity. Using the natural bond orbital analysis, molecular electrostatic potential, electron-localization function, density of state calculations, and charge-decomposition analysis, the electronic properties of the complexes were calculated to ascertain the notable effects of the adsorbing these analytes on the C4N3. NBO method showed charge-migration from the C4N3 to the pollutants in the POPs@C4N3 complexes. Transition-state (TS) theory was employed to estimate the recovery period at 300 K in order to estimate the reusability of the C4N3. Recovery times at 300 K were 4.76 × 10-9, 1.68 × 10-11, 4.16 × 10-10, and 2.2 × 10-9 s for BA@C4N3, CR@C4N3, TP@C4N3, and TD@C4N3, respectively, indicating rapid sensor regeneration. These findings highlight the novelty of C4N3 as a reusable sensing surface for persistent organic pollutants, paving the way for practical applications in environmental monitoring.