Visible and near-infrared light activated azo dyes

This review mainly introduces azo dyes that can be driven by visible /near-infrared light in recent years. [Display omitted] The photoisomerization properties of azo derivatives have been widely used in the fields of materials and biology. One serious restriction to the development of functional azo-based materials is the necessity to trigger switching by UV light, which damage the corresponding surfaces and penetrate only partially through the matter. Therefore, developing the visible and near-infrared light activated azo switches can solve this problem. This review provides a summary of molecular design strategies for driving the isomerization of azo derivatives with visible light and near-infrared light: (1) smart design directly excited by visible light, (2) the addition of upconversion nanoparticles, (3) the employment of two-photon absorption, (4) indirect excitation in combination with metal sensitizer.