Highly photoluminescent two-dimensional imine-based covalent organic frameworks for chemical sensing
Qiang Gao, Xing Li, Guo‐Hong Ning, Kai Leng, Bingbing Tian, Cuibo Liu, Wei Tang, Hai‐Sen Xu, Kian Ping Loh
Abstract
The strong π–π interactions in the stacking layers of two-dimensional covalent organic frameworks (2D-COFs), together with rotationally labile imine linkages, make most of the solid state imine-linked COFs non-fluorescent due to fluorescence quenching processes. Here, we report the successful synthesis of highly photoluminescent imine-based 2D-COFs by integrating a non-planar building unit with a pyrene-based unit and transforming the COF into spherical, sub-micron particles. High photoluminescence quantum yields (PLQY) were achieved with COF sub-micron particles dispersed in organic solvents. The as-prepared COF sub-micron particles can be used as a chemical sensor for the detection of explosive chemicals, with high sensitivity and selectivity (up to ppm level).