Two three-dimensional coordination polymers as fluorescence probes for the detection of nitrobenzene, tetracycline, fluazinam and their application in green pepper.

Two coordination polymers (CPs), [Zn(L)(phen)](1) and [Cd(HL)(2,2-bpy)(HO)](2), were synthesized by using 2',3,3',5,5'-Diphenyl ether pentacarboxylic acid (HL), phenanthroline (phen), and 2,2'-bipyridine (2,2'-bpy) under hydrothermal conditions. The L ligand adopts the μ-к: к: к: к: к: к mode in 1 and the μ-к: к: к: к: к mode in 2. Sensing experiments show that 1 and 2 are fluorescence probes with high sensitivity and rapid detection of nitro explosives, antibiotics, and pesticides. In order to verify the ability of 2 to detect FLU in actual samples, we performed a spiked recovery experiment in green pepper water. The spiked recoveries were 97.77-101.18 %. Interestingly, because HL is not completely deprotonated in 2, there is abundant hydrogen bonding, which makes the fluorescence quenching rate higher and the detection limit lower. The possible fluorescence quenching mechanism of 1 and 2 can be explained by their UV-VIS absorption spectra and orbital energy levels.