Multiple Stimulus Response 2D Framework Constructed by a Flexible Cyclotriphosphazene-Derived Carboxylic Acid Linker: Synthesis, Characterization, and Fluorescence Sensing to Phenolic Pollutants and Small-Molecule Drugs

Hexachlorocyclotriphosphazene is one of the most representative phosphazene compounds which have been proved to have broad application prospects in many fields. However, it is an emerging research perspective to combine cyclotriphosphazene-derived polycarboxylic acid compounds with lanthanides for the construction of Tb-DPCP metal-organic framework (MOF) materials. Herein, a Tb-DPCP MOF, (CH3)2NH2[Tb3(HDPCP)(DMF)(H2O)3]·6DMF (1), was successfully prepared via the reaction of H12HDPCP [hexa(4-carboxyphenoxy) cyclotriphosphazene] and Tb(NO3)3·6H2O under the solvothermal condition. Through fluorescence sensing experiments, it was found that both nitrophenols and chlorophenols could cause the fluorescence quenching of compound 1. At the same time, the compound also exhibited nice trace detection ability for small-molecule drugs (moxifloxacin hydrochloride, balsalazide disodium, and colchicine); the limits of detection were all lower than 0.2 μM. These experimental results fully demonstrated the potential application value of 1 as a multifunctional fluorescent sensor.