NH₂-UiO-66 Metal–Organic Framework Nanoparticles for Hydroxide Ion Conductive Photoswitches

Stimuli-responsive conductive MOF nanoporous materials have been considered to have great potential for photoelectric conversion, information processing, bioelectronics, and smart devices. However, light-regulating hydroxide ion conduction of MOFs is rarely reported. Herein, a reversible optical switch on hydroxide ion conduction has been achieved based on the intrinsic localized photothermal heating of NH2-UiO-66 nanoparticles. The amino group on the organic ligand of NH2-UiO-66 can build a hydrogen-bond network with water molecules to promote hydroxide ion transport in the nanochannel and cause an absorption band in the visible light region. Irradiated by visible light, NH2-UiO-66 nanoparticles can absorb light and convert it into heat, resulting in partial removal of water molecules in the nanopores and destroying the hydroxide ion transport path. Then, the hydroxide ion conductivity decreased by 2 orders of magnitude. When turning off the light, the hydroxide ion conductivity can restore quickly. This work will promote the development of remotely controlled hydroxide ion conductive smart devices.