DETECTION OF CREATININE BY A DESIGNED RECEPTOR

An artificial receptor has been designed to bind creatinine with a col or change (chromogenic response) caused by proton transfer from one en d of the receptor to the other. The receptor was synthesized and found to extract creatinine from water into chlorocarbon solvents. The colo r change in the organic layer is specific for creatinine relative to o ther organic solutes, and it is selective far creatinine relative to s odium, potassium, and ammonium ions. The chromogenic mechanism is reve aled by x-ray crystal structures of creatinine, the free receptor, and the complex, showing ''induced fit'' binding resulting from electroni c complementarity between host and guest.