Photoswitchable Azobenzene/Cyclodextrin Host‐Guest Complexes: From UV‐ to Visible/Near‐IR‐Light‐Responsive Systems

Abstract

Abstract UV‐light‐responsive azobenzene (Azo)/cyclodextrin (CD) host‐guest complexes are attractive for designing smart stimuli‐responsive materials, and have been extensively investigated over the past three decades. However, when applied in biomedical fields, as a result of the harmfulness and poor penetrability of UV light to human tissue, Azo/CD host‐guest complexes responsive to light of longer wavelengths is required. In this Minireview, we reviewed the traditional UV‐light‐responsive Azo/CD host‐guest systems and developments to red‐shift the switching light to the visible or even to the near‐infrared (NIR) light region. “Indirect” methods, including upconversion and two‐photon processes, and “direct” methods to chemically modify Azo molecules for red‐shifting the inducing light were summarized and compared. In addition to biomedical applications, we provide an overview of the potential of visible/NIR‐light‐responsive Azo/CD host–guest complexes in the design of intelligent multifunctional supramolecular materials that function through orthogonal light control.