Hydrazone Switch-Based Negative Feedback Loop

A negative feedback loop that relies on the coordination-coupled deprotonation (CCD) of a hydrazone switch has been developed. Above a particular threshold of zinc­(II), CCD releases enough protons to the environment to trigger a cascade of reactions that yield an imine. This imine sequesters the excess of zinc­(II) from the hydrazone switch, hence lowering the effective amount of protons, and switching the cascade reactions “OFF”, thus establishing the negative feedback loop.