Computational evaluation of Dieticyclidine adsorption and detection using aluminum and zinc functionalized C60 fullerene for drug detection.

Dieticyclidine (PCDE), a dissociative anesthetic related to phencyclidine, poses significant public health challenges due to its severe psychoactive effects and the lack of rapid, field-deployable detection methods. Conventional analytical techniques, such as GC-MS and LC-MS, while accurate, are costly, time-consuming, and require specialized laboratory infrastructure. This computational study employs density functional theory (DFT), time-dependent DFT (TD-DFT), and quantum theory of atoms in molecules (QTAIM) to evaluate the adsorption and sensing performance of pristine C60, aluminum-doped (AlC59), and zinc-doped (ZnC59) fullerenes toward PCDE. Calculations were performed at three theoretical levels (B97D/6-31G(d), ωB97XD/6-31G(d), and M06-2X/LANL2DZ) and showed qualitatively consistent trends for the main adsorption and sensing descriptors. According to the results, AlC59 showed strong adsorption energy (-47.56 kcal mol-1), marked electronic-structure perturbation, and an increase in the absorption wavelength from 521 to 771 nm in the presence of PCDE, along with an extremely long recovery time, making it a candidate for further experimental evaluations as an irreversible adsorbent and disposable colorimetric/electrochemical sensor. In contrast, ZnC59 shows moderate adsorption (-19.33 kcal mol-1), a favorable recovery time (102 s), and a comparable bathochromic shift to 765 nm, positioning it as a more theoretical candidate for reversible colorimetric sensing, which warrants further experimental evaluation. NCI, ELF, and LOL analyses consistently reveal that adsorption is governed predominantly by weak van der Waals interactions, with enhanced localized attractive contributions in the doped systems. We believe that the findings of this study can serve as a valuable theoretical guide for future experimental work.