Light enhanced proton conductivity in a terbium phosphonate photochromic chain complex

Abstract

Crystalline complexes that exhibited light switchable proton conductivity are of great interest but still a challenge in material science. Herein, a terbium phosphonate chain complex was synthesized through assembly of electron-rich phosphonate units, electron-deficient polypyridine components and paramagnetic Tb3+ ions. Via light irradiation and heat treatment, the photogenerated radicals could simultaneously and reversibly tune the photochromic, luminescent and magnetic properties. Originated from the abundant hydrogen bonding networks formed between PO3 groups and lattice water molecules, proton conductive behaviour was explored with high proton conductivity of (1.74±0.19)×10−3 S cm−1 at 80 °C and 100% relative humidity. Importantly, accompanied with the colorless sample changed to blue, the proton conductivity increased about 20% after room temperature light illumination, implying that light irradiation could act as an external stimulus to enhance the conductive properties of original material. This work innovatively realized the light responsive conductive property in the electron transfer photochromic materials, providing a novel strategy for the construction of smart materials.