How do the lanthanide coordination polymers achieve luminescence quenching in the presence of nitrobenzene?

Luminescence quenching is a phenomenon where the emission intensity of a luminescent material decreases in the presence of a quencher. Understanding the mechanism of quenching is crucial for developing efficient sensors.

The luminescence quenching in the presence of nitrobenzene is achieved through photoinduced electron transfer. The low-lying π* orbitals of nitrobenzene, stabilized by the -NO₂ substituent, act as the lowest unoccupied molecular orbitals (LUMOs). These orbitals have energies lower than the conduction band of the coordination polymers, driving electron transfer from the polymers to nitrobenzene and resulting in fluorescence quenching.