Cholesteryl naphthalimide-based gelators: Their applications in the multiply visual sensing of CO2 based on an anion-induced strategy

Several cholesteryl naphthalimide-derived compounds have been sythesized and developed as CO2 sensors. The derivatives, incorporating ether chains, were found to be capable of gelating various organic solvents, due to the modulation of the hydrophilicity/hydrophobility properties of them. The resulting organogels were well characterized by field emission scanning electron microscopy (FE-SEM), FT-IR spectroscopy, concentration- and temperature-dependent H-1 NMR spectra, and powder X-ray diffraction (PXRD). These gelators can be applied as fluorescent sensors for CO2 in DMSO solutions via the anion-triggered strategy. Furthermore, the resulting organogelation systems in DMSO could also provide visual sensing means for CO2 via the reversible solution-to-gel transition. Particularly, the re-gelation of DMSO induced by CO2 bubbling could be directly observed without the aid of the heating-and-cooling operation. And the reversible sensing process could be repeated several times with the excellent chemical stability of the gelation system after the repeated stimuli of fluoride anion, CO2 and N-2 with heating. These investigations indicate the developed organogelators own the applicable potential in the CO2 detection. (C) 2017 Elsevier Ltd. All rights reserved.