Theoretical study on the phenylpropanolamine drug interaction with the pristine, Si and Al doped [60] fullerenes

Phenylpropanolamine (PPA) is a popular drug of abuse and its detection is of great importance for police and drug communities. Herein, we investigated the electronic sensitivity and reactivity of pristine, Al and Si doped C-60 fullerenes to the PPA drug, using density functional theory calculations. Two adsorption mechanisms were predicted for PPA on the pristine C-60 including cycloaddition and adsorption via -NH2 group. It was found that the pristine C-60 has a good sensitivity to this drug but suffers from a weak interaction (adsorption energy similar to-0.1 kcal/mol) because of structural deformation and aromaticity break. The PPA is adsorbed on the Al or Si doped C-60 from its -OH or -NH2 groups. The Al-doping significantly improves the reactivity of C-60 but decreases its electronic sensitivity. Unlike the Al-doping, the Si-doping increases both the reactivity and electronic sensitivity to the PPA drug. At the presence of PPA drug, the conductivity of the Si-doped C-60 considerably increases due to the HOMO-LUMO gap reduction by about 30.3%. Different analyses were used to obtain the results including nucleus independent chemical shift (NICS), density of states (DOS), molecular electrostatic potential (MEP), frontier molecular orbitals (FMO), etc.