Frontispiece: Photoswitchable Carbohydrate‐Based Macrocyclic Azobenzene: Synthesis, Chiroptical Switching, and Multistimuli‐Responsive Self‐Assembly

Abstract

A switchable carbohydrate‐embedded macrocyclic supramolecular gelator has been generated by a one‐pot O‐alkylation mediated macrocyclization approach. The synthesized azobenzene‐based glycomacrocycle can be reversibly isomerized between E and Z isomers upon light irradiation with excellent photostability and thermal stability (t1/2=51 days at 20 °C for the Z isomer). The macrocycle showed chirality transfer, multistimuli‐responsive organogel formation behavior upon exposure to external triggers, and helical inversion during the self‐assembly and gel formation. For more details, see the Communication by J. Xie et al. on page 14996 ff.

Photoprogrammable Mesogenic Soft Helical Architectures: A Promising Avenue toward Future Chiro‐Optics

“…Moreover, the azobenzene‐based macrocyclic molecule was designed to change the optical chirality dramatically and to avoid multi‐conformation of a single trans ‐ or cis ‐isomer during photoisomerization. [ 104–107 ] Such macrocyclic materials were synthesized through cyclization between the azobenzene derivatives and chiral sugars (Figure 8E‐a), which transferred the chirality to the mesogenic azobenzene moiety, enabling significant CD modulation of not only the absorption, but also the sign of the Cotton band (i.e., the chirality of the material) (Figure 8E‐b). In addition, such macrocyclic materials exhibited the gel state in cyclohexane and ethanol, with interconversion between gel and sol through diverse stimuli, including light, temperature, and mechanical force.…”