Tunable dual emission of fluorescence-phosphorescence at room temperature based on pure organic supramolecular gels

A facile fabrication strategy of fluorescence-phosphorescence dual emissive materials based on the supramolecular gels was proposed in this work. In comparison with complicated fabrication of conversional dual emissive materials, supramolecular gels are formed just through a simple heating and cooling of solution containing a gelator and phosphor. The gel system is pure organic without any metal ions. Herein, the self-assembly of gelator N, N-dibenzoyl-L-cystine (DBC) resulted in the formation of gel system. The phosphor 3,5-Dibromoquinoline (BrQ) entrapped in the gels endowed gels with fluorescence-phosphorescence dual emission. Upon 315 nm UV irradiation, strong room temperature fluorescence and phosphorescence emission were observed at 367 and 550 nm, respectively. The ability of dual emission at room temperature could be attributed to the ordered microstructure of the supramolecular gels, effectively avoiding the non-radiative transition of BrQ. In addition, the gel system exhibited environmental responsiveness including thermal, pH and redox response due to the structural feature of DBC gels. The dual emission can be tuned by this responsiveness. Particularly, the deoxygenation of gel system is not required. Conversely, the dissolved oxygen in the system can be employed for redox reaction without the addition of any other oxidant.