Expanding the Knowledge of the Selective-Sensing Mechanism of Nitro Compounds by Luminescent Terbium Metal-Organic Frameworks through Multiconfigurational Calculations.

The current research shows that the excited-state dynamics of the antenna ligand, both in the interacting system sensor/analyte and in the sensor without analyte, is a safe tool for elucidating the detection principle of the luminescent lanthanide-based metal-organic framework sensors. In this report the detection principle of the luminescence quenching mechanism in two Tb-based MOFs sensors is elucidated. The first system is a luminescent Tb-MOF [Tb(BTTA)(HO)] (HBTTA = 2,5-bis(1H-1,2,4-triazol-1-yl) terephthalic acid) selective to nitrobenzene (NB), labeled as . The second system is {[Tb(DPYT)(BPDC)(NO)]·HO} (DPYT = 2,5-di(pyridin-4-yl) terephthalic acid, BPDC = biphenyl-4,4'-dicarboxylic acid), reported as a selective chemical sensor to nitromethane (NM) , labeled as . The luminescence quenching of the MOFs is promoted by intermolecular interactions with the analytes that induce destabilization of the T electronic state of the linker "antenna", altering thus the sensitization pathways of the Tb atoms. This study demonstrates the value of host-guest interaction simulations and the rate constants of the radiative and nonradiative processes in understanding and elucidating the sensing mechanism in Ln-MOF sensors.