Sensitive detection of hazardous explosives via highly fluorescent crystalline porous aromatic frameworks

Abstract

A three-dimensional (3D) porous aromatic framework (PAF-14) with high fluorescence quantum yield was synthesized from luminescent monomer of tetra(4-dihydroxyborylphenyl)germanium (TBPGe) building blocks. The powder X-ray diffraction (PXRD) analysis of the experimental and simulated patterns indicate that PAF-14 is highly crystalline with ctn topology. The Argon sorption measurement indicates that PAF-14 possesses high surface area (Brunauer Emmet Teller surface area: 1288 m2 g-1). Significantly, the introduction of germanium into PAF-14 skeletons may bring about a low-lying lowest unoccupied molecular orbital (LUMO) and the crystalline polymeric backbones enhance the sensitivity of electron delocalization. Therefore the designed PAF-14 exhibits high fluorescence quenching ability for hazardous explosives, such as nitrobenzene, 2,4-DNT (2,4-dinitrotoluene) and TNT (2,4,6-trinitrotoluene).