Multi-state regulation of the dihydrogen phosphate binding affinity to a light- and heat-responsive bis-urea receptor.

A responsive bis-urea receptor can be switched between three isomers using light and heat as evidenced by (1)H NMR and UV-vis spectroscopy. Anion binding experiments ((1)H NMR titrations, ESI-MS) reveal a high selectivity for dihydrogen phosphate. Importantly, a large difference in binding affinity to the interchangeable isomers is observed, which is further rationalized by DFT calculations. As a consequence, the amount of bound substrate can be controlled via photo- and thermal isomerization in a three-step process.