A highly stable fluorescent terbium MOF (Tb4(paip)6·1.2H2O,paip =5-(1H-pyrazole-4-yl)isophthalate)showing a sharp green emission (545 nm) and a quantum yield of 21.0％ was successfully synthesized.This compound is shown to be a recyclable sensor for detecting picric acid in aqueous solution with both high sensitivity and selectivity,attributed to the electron transfer quenching mechanism.