Dual luminescent covalent organic framework for nitro-explosives detection
The assembly of π-electron rich fluorescent monomers (4, 4', 4'', 4'''-(ethene-1, 1, 2, 2-tetrayl) tetraaniline) (ETTA) and 9, 10-anthracenedicarboxaldehyde are selected to build a new dual luminescent covalent organic framework (DL-COF) of high thermal and chemical stability by using simple Schiff-base reaction. The resultant crystalline framework contains tetraphenylethylene (TPE) units at the vertices and the classic anthracene units at the edges, linked through imine (-C=N-) bond in rhombic-shaped sheets, which offers high fluorescence and binding sites for molecular recognition, respectively. These synergistic functions of the framework units endow the unique platform for chemical sensing. Due to synergistic action, DL-COF exhibits the best nitro explosives detection of high sensitivity (K_sv~ 106 . M-1, K_q ~ 1015 . M-1.s-1 ) and selectivity (at ppb level) among previously reported COFs and MOFs based sensors under similar conditions. To the best of our knowledge, this is the first investigation of anthracene based COF for such an application. Particularly, the incorporation of anthracene unit strategy into COF framework is not only increased the structural assortment but lead to the exceptional sensing capabilities towards nitro explosives.