Cu‐MOF‐74 as Fluorescent Probe: Selective Optical Sensor for H₂S Gas

Abstract In order to address the air quality issues and industrial gas leakages effectively, gas sensors must be highly sensitive, selective, stable, cost‐effective, and with high life time. We present here a facile solvothermal method to synthesize a Cu based metal‐organic framework (Cu‐MOF‐74) and demonstrated its potential as a selective fluorescent probe for environmental H 2 S gas detection. Cu‐MOF‐74 based fluorescence sensor shows strong affinity towards H 2 S with the limit of detection as low as 7 ppm., Though Cu‐MOF‐74 based sensor exhibited high sensitivity and selectivity for H 2 S gas over H 2 , SO 2 and NH 3 , Co‐MOF‐74 is inactive towards H 2 S sensing. The increased fluorescence intensity in presence of H 2 S gas as well as the decreased fluorescence intensity in presence of NO 2 gas was investigated by experimental observation and theoretical calculation. In presence of H 2 S gas, interaction between Cu and sulphur atoms occur, the bond between Cu and ligand. This reduces the extent of ligand to metal charge transfer, resulting in increase in fluorescence intensity. The present attempt led to the progress of highly selective and sensitive fluorescence‐based environmental gas sensing probe using metal organic framework with a wide operating temperature ranging of 25 °C to 90 °C.