Self-Assembly of Hollow Organic Nanotubes Driven by Arene Regioisomerism

Arene regioisomerism in low-molecular-weight gelators can be exploited as a tool to modulate the micro-structures of the corresponding xerogel networks by using the three different possible substitution patterns ortho, meta and para. This aromatic regioisomer-driven strategy has been used with a cholesterol-based gelator to prepare hollow self-assembled organic nanotubes (S-ONTs) with inside and outside diameters of ca. 35 and 140 nm, respectively. Electron microscopy imaging and theoretical calculations were employed to rationalize the formation mechanism of these S-ONTs. From the three possible regioisomers, only the ortho-disubstituted cholesteryl-based gelator showed the optimal angle and distance between substituents to afford the formation of the cyclic assemblies required for nanotube growth by assembling 30-40 units of the gelator. This study opens fascinating opportunities to expand the synthesis of controllable and unique microstructures by modulating geometrical parameters through aromatic regioisomers.