# Temporally Controlled Supramolecular Catalysts with pH-Dependent Activity

## TL;DR

Scientists developed a way to control chemical catalysts over time by using pH-sensitive materials that change activity in response to environmental conditions.

## Contribution

A programmable strategy using pH-responsive supramolecular catalysts to temporally control phosphodiester cleavage is introduced.

## Key findings

- Activated carboxylic acids enable transient acidification and spontaneous pH recovery in semiaqueous media.
- Metal complexes with cyclic polyamine and calix[4]arene show time-dependent catalytic performance under pH modulation.
- The system allows programmable regulation of phosphodiester cleavage through pH-dependent activity.

## Abstract

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.