Efficient Ultraviolet Light Detector Based on a Crystalline Viologen-Based Metal–Organic Framework with Rapid Visible Color Change under Irradiation

A convenient colorimetric molecular system constructed by the zinc viologen-carboxylate framework is developed for naked eye detection of instantaneous UV exposure levels. Only narrow-band absorption in UV regions and a unique interpenetrated structure of its colorless crystal enable the system to give a fast response toward UV irradiance with intensity as low as 0.001 mw/cm2.