Supramolecular Nanovalves Controlled by Proton Abstraction and Competitive Binding

A functional integrated nanosystem for trapping and releasing molecules under deliberate control is prepared. The openings to nanosized pores in silica particles are regulated by gatekeeper supermolecules that are controlled by pH stimulation and competitive binding. Controlled release of fluorescent probe molecules is demonstrated using (i) organic bases, (ii) fluorodialkylammonium ions, and (iii) metal ions as actuators. The rate of the release of the probe molecules depends on the size of the base, the dimension of the probe molecules, and the binding affinity of the metal/fluorodialkylammonium cations employed.