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.