Helical stacking tuned by alkoxy side chains in π-conjugated triphenylbenzene discotic derivatives

We report oil the synthesis and self-assembly of a new series of discotic molecules containing triphenylbenzene as the core and alkoxy side chain with varying length. It was found that compounds 3a-c, 4b and 5b could form stable gels in several apolar solvents. Transmission electron microscopy (TEM) images revealed that their morphologies were very different for the different alkoxy-substituted organogels. In toluene or hexane, 3b and 3c resulted in both left- and righthanded helical fibers, whereas 3a resulted in straight rigid fibers; 4b and 5b resulted in most straight fibers with a few twisted fibers. no results from FT-IR and UV/Vis absorption spectroscopy indicated that the hydrogen bonding and pi-pi interactions were the main driving forces for the formation of the self-assembled gels. Further detailed analysis of their aggregation modes were conducted by UV-visible absorption spectra and X-ray diffraction (XRD) measurements. Based on these findings, the influence of these peripheral alkoxy substituents on the gel formation and the aggregation mode were discussed. The special enhanced fluorescent emissions, which resulted from aggregation, were also found in the gel phase.