Two-mode selective sensing of H2PO4- controlled by intramolecular hydrogen bonding as the valve

A novel fluorescent sensor L1 exhibiting selective H2PO4- sensing ability was synthesized. The initial conformation of L1 was controlled via intramolecular hydrogen bonding and the switching/gating function was achieved by disturbing the intramolecular hydrogen bonds before and after interaction with H2PO4-.