Self-Assembled Sugar-Substituted Perylene Diimide Nanostructures with Homochirality and High Gas Sensitivity

A new symmetrical sugar-based perylenediimide derivative PTCDI-BAG is synthesized and its aggregate morphologies and formation mechanisms are studied in detail in the mixed solvent system water/N,N-dimethylformamide (H2O/DMF) with changing volume ratios. PTCDI-BAG molecules self-assemble into planar ribbons in 20/80 and 40/60 H2O/DMF (v/v), but their chiralities are opposite according to recorded circular dichroism (CD) spectra. With a further increase of the water content, only left-handed helical nanowires are obtained in 60/40 and 80/20 H2O/DMF (v/v) mixtures. By combining density functional theory (DFT) calculations with the experimental investigations, it is proposed that kinetic and thermodynamic factors play key roles in tuning PTCDI-BAG structures and helicity. The formation of the ribbon is thermodynamically controlled in the 20/80 H2O/DMF system, but kinetically controlled nucleation followed by thermodynamically controlled self-assembly plays the governing roles for the formation of nanoribbons in 40/60 H2O/DMF. Devices based on single nanoribbons for hydrazine sensing exhibit better performance than nanofiber bundles obtained in this study and achiral nanostructures reported in previous study. This study not only provides an elaborated route to tuning the structures and helicity of PTCDI molecules, but also provides new possibilities for the construction of high-performance nanodevices.