Elucidating the mechanistic sensing capability of novel tetragonal graphene quantum dot towards tobacco alkaloids: a DFT study

Smoking is the g`reatest preventable cause of mortality all over the world as it causes lung cancer, vascular disease, peptic ulcers, coronary heart disease, stroke and harm to the developing fetal brain, and numerous respiratory issues, such as chronic bronchitis, emphysema, pulmonary hypertension, obstruction of tiny airways, and chronic obstructive pulmonary diseases. These diseases are mainly caused by smoking of tobacco products, including pipe tobacco, snuff, cigars, and cigarettes. To overcome the dangerous and adverse effects of tobacco alkaloids, the utilization of novel class of quantum dots, the graphene quantum dot (GQD) has not yet been thoroughly investigated. To fill this gap, the mechanistic sensing capability of the tetragonal graphene quantum dot towards tobacco alkaloids including anabasine (Anab), anatabine (Anat), myosmine (Myos), nitrosoanabasine (NAB), nitrosoanatabine (NAT), and nornicotine (NOR) has been investigated by employing first-principles DFT and TD-DFT computations. The computational tools have been utilized to investigate the interaction energies, the energy gap (FMO analysis), non-covalent interactions (NCI analysis), transfer of charges (QNBO), and the nature and strength of intermolecular interactions (QTAIM analysis). The NOR@T-GQD complex has the greatest interaction energy (− 20.1051 kcal/mol) among all the studied complexes. Also, the complex NOR@T-GQD has the lowest energy gap (1.072 eV) and chemical hardness (0.536 eV) which indicates the highest conductivity (2.486 × 10⁹), shortest recovery time (3.005 × 10⁻¹⁶), and highest sensing response (2.326). UV–Vis analysis explored the maximum absorbance wavelength, excitation energy, and oscillator strength for the studied system and the thermodynamic analysis explored the spontaneity of the interaction process of the studied complexes. So, all the investigation parameters have proved that the tetragonal graphene quantum dot-based sensor is an influential sensing material towards all studied tobacco alkaloids especially for the tobacco alkaloid nornicotine.