The effects of the linker length on iodine adsorption and fluorescence sensing property of the N, O, P containing covalent organic frameworks

Covalent organic frameworks (COFs) are novel porous organic materials with structural tunable features and have great potential applications in iodine adsorption and fluorescence sensing. We explore the effect of linker length on the function of the COFs prepared through the Schiff base aldehyde-amine polycondensation with different linkers in lengths. The linker length affects the specific surface area, aperture, pore volume, and electron density of the COFs, thus affecting the ability to bind with other substances. The synthetic HPDA and HDAT in this report showed excellent iodine adsorption of 4.53 and 3.92 g g(-1), respectively. Meanwhile, HPDA and HDAT are quite sensitive to the fluorescence sensing of picric acid (PA) and o-nitrophenol (o-NP) with their limits of detection of 1.86 x 10(-11), 4.69 x 10(-11) mol L-1, respectively. HPDA and HDAT can be outstanding adsorbents for iodine and excellent fluorescent sensors for PA and o-NP, respectively.