In-silico insights into fullerene-based nanostructures as potential platforms for eticyclidine adsorption and detection.

Eticyclidine (ETC) is a dissociative arylcyclohexylamine whose capture and detection are relevant to forensic and environmental monitoring. We evaluated pristine C60 and substitutionally doped BC59 and SiC59 nanocages as candidate adsorption and sensing platforms using B97D/6-31G(d) calculations in the gas phase and CPCM water, supported by frontier-orbital, NBO, QTAIM, and NCI analyses. We also used an independent gas-phase M06-2X/6-311G (d,p) benchmark to test the qualitative adsorption trend. The BSSE-corrected B97D adsorption energies were -8.52, -31.15, and -35.42 kcal mol-1 in the gas phase and -7.44, -33.08, and -41.45 kcal mol-1 in water for C60@ETC, BC59@ETC, and SiC59@ETC, respectively. The M06-2X benchmark preserved the same qualitative affinity order, with uncorrected gas-phase adsorption energies of -7.11, -36.68, and -47.74 kcal mol-1. The results reveal an adsorption-response-recoverability trade-off rather than a single universally optimal material: SiC59 is predicted to be most suitable for persistent ETC capture/removal, pristine C60 is the most reversible, and BC59 provides the highest final gap-derived conductivity among the ETC complexes but has an extremely long estimated recovery time, making it more plausible as a disposable conductivity-response platform than a rapidly reusable sensor. These conclusions remain theoretical screening predictions; CPCM describes bulk dielectric polarization but not explicit first-shell hydration or device-level transport.