Fabrication of 2D Metal-organic frameworks (MOFs) nanosheets and investigation its fluorescence response to pesticide molecules

Pesticides as a kind of toxic chemicals widely used for a long time, not only pollute the environment, but also affect people's health, and do serious harm to human body, soil and environment. Therefore, it is very necessary to exploit a portable and environmentally friendly method to detect pesticides with high sensitivity. Herein, a new luminescent metal-organic framework ([Zn(TPYBDC)H2O]n, TPYBDC2- = 4'-(pyridin-4-yl)-[2,2':6',2''-terpyridine]-4,4''-dicarboxylate) with 2D coordination layers has been designed and assembled using 4'-(pyridin-4-yl)-[2,2':6',2''-terpyridine]-4,4''--dicarboxylic acid as the ligand. The as-synthesized Zn-LMOF is exfoliated to ultrathin 2D nanosheets (45 nm) to form the luminescence colloidal sensor by destroying the weak interaction between the coordination layers such as H-bonding between the matrix H2O and the coordination carboxyl oxygen, the interactions among interlayer conjugated aromatic rings. Investigation its recognition and detection ability towards chemical pesticides shows it can sensitively sense pesticides such as imidacloprid, nitenpyram and dinotefuran via fluorescence quenching effect with very low detection limit (LOD). Imidacloprid as a typical case, the LOD value of 0.562 M and the recoveries for the simulated agriculture environmental samples in the range of 94%115% suggests the as-fabricated 2D Zn-MOF nanosheets colloidal sensor (Zn-LMOF probe) are most promising candidates for sensing chemical pesticides.