Temporally Controlled Supramolecular Catalysts with pH-Dependent Activity.

Controlling the activity of synthetic catalysts over time remains a key challenge for designing adaptive chemical systems. Supramolecular phosphodiesterase mimics can be particularly sensitive to pH, with some of them presenting active species that operate only under basic conditions. In this work, we have focused on a dissipative strategy that exploits activated carboxylic acids (ACAs) to temporally modulate pH and, consequently, the activity states of these catalysts. ACAs undergo combined acid-base and decarboxylation processes, enabling transient acidification followed by a spontaneous return to higher pH. We first analyze the acid-base behavior of a selected ACA through potentiometric studies to identify the parameters governing the lifetime of the dissipative state in semiaqueous media. Guided by these insights, we investigate the time-dependent catalytic performance of metal complexes based on a cyclic polyamine and a bifunctional calix[4]-arene bearing both a cyclic polyamine and a guanidinium group. This approach provides a programmable way to regulate phosphodiester cleavage catalysis, laying the foundations for future adaptive and temporally controlled chemical systems.