Copper indium sulfide quantum dots enabling quantitative visible light photoisomerisation of ( E )-azobenzene chromophores

Azobenzene derivatives have long been studied for their photochromic behaviour. One of the greatest challenges in this field is the quantitative (E) to (Z) photoconversion triggered by visible light irradiation. In this work, the synthesis and characterization of CuInS₂ quantum dots (CIS-QDs) appended with azobenzene units are reported: quantitative (E) → (Z) isomerisation is obtained by visible light (e.g., λ_ex = 533 nm). Interestingly, catalytic amounts of CIS-QDs allow the full photoconversion of ungrafted (E)-azobenzene derivatives into the corresponding (Z)-isomers using visible light. This peculiar behaviour is associated with the direct complexation of the (Z)-isomer on the QD surface.