Analysis of a bicyclic, triple disulphide molecular nanopropeller

Abstract

The bicyclic, triple disulphide molecule, HC(S₂)₃CH called propellerdisulphide (PS), has been quantum chemically shown in this work to be a stable, isolated molecule with potential applications to nanoparticle transportation for biomedical uses. The desire of hydrogen disulphide to twist in its lowest energy conformation is exploited to create a bicyclic compound that has non-zero τ(C–S–S–C) dihedral angles and is, consequently, also optically active. This angle creates an inclined plane or screw-like pattern within the molecule that can direct particles in a way similar to that of a macroscopic screw. The barrier to rotation for directly linking PS to a model fullerene surface is 6.00 kcal mol⁻¹ while linking it through a pyrrolidine bridging group is nearly double this. It is suggested herein that pulsed THz energy could excite the low-lying PS twisting vibrational frequency relative to the nanoparticle surface over several quanta. This action could overcome the barrier to rotation such that the PS ligand will spin and give propeller-like properties for enhancing the movement of fullerene nanoparticles. Applications of this behavior stretch into medicine since endohedral fullerene nanoparticle cages can encapsulate imaging or therapeutic compounds, and directing the nanoparticles to the desired site more efficiently could make a significant impact on treatment.