Spontaneously hierarchical self-assembly of nanofibres into fluorescent spherical particles: a leap from organogels to macroscopic solid spheres.

Abstract

The spontaneous hierarchical self-assembly of organic small molecules into macroscopic architectures with excellent photophysical properties and highly-ordered structures has rarely been reported to date. In this work, we find that the organogel of SY1 formed in ethyl acetate could spontaneously assemble into macroscopic spherical particles with a unique morphology and photophysical properties. Upon increasing the aging time, the gel gradually collapsed and then transformed into many macroscopic spheres (SY1-balls) with an average diameter of ca. 500 μm and strong yellow emission. In view of the emission properties and the porous structure of the SY1-balls, they were successfully applied in the adsorption and detection of heavy metal ions. More interestingly, SY1 shows different assembly behaviours in toluene solution when mixed with a triphenylamine derivative (TPA1). Macroscopic particles (ST-balls) with a core-shell structure were obtained, which were quite different from the SY1-balls in morphology and emission colour. So far as we know, many studies have focused on the change of the micromorphology of a gel, while the spontaneous self-assembly of organogels into macroscopic particles has been reported in this work for the first time. This work enriches the present study on organogels and plays an important role in further understanding the hierarchical self-assembly of organogels.