Macroscopic manifestation of a vapour-induced molecular switching phenomenon

Abstract

We report a molecular switching event that leads to a reversible large-scale expansion of a floating porphyrin Langmuir layer residing at the air–water interface. This vapour-induced protonation–deprotonation mechanism, responsible for the expansion–contraction cycle, could potentially be exploited in applications in which a physical shape-change is triggered by exposure to an acidic or basic gas.