The Growing Field of Photoswitchable Macrocycles: A Promising Way to Tune Various Properties with Light

Abstract

Thanks to supramolecular interactions of macrocyclic compounds with their guest ions or molecules, macrocycles have found wide applications in molecular and chiral recognition, separation, transportation, molecular machines, and so on. Photoswitchable macrocycles are especially appealing and attracting more and more interest because the embedded molecular photoswitch enables dynamic control of molecular shape, conformation, and different properties by light, a non‐invasive, remote and highly tunable stimulus. With available photochromic compounds, various photoswitchable macrocycles have been developed. In this review paper, we describe the recently reported photoswitchable macrocyclic compounds, with a focus on the control of the macrocyclic structure, dynamic, photo or thermal isomerization, as well as their applications on encapsulation and release of ionic or aromatic species, on the reversible modulation of chemical, biological, electronic, fluorescent and chiroptical properties by light.

Multichromophoric photoswitches for solar energy storage: from azobenzene to norbornadiene, and MOST things in between

“…Multichromophoric photoswitches featuring various azoarene derivatives have been reviewed in detail elsewhere, 20,46,54 though here we will focus specifically on the potential of multistate azobenzene photoswitches for energy storage applications. In general, they can be classified according to their structure as linear, non-linear or bent, 55 branched, 56 tripodal C 3 symmetric, 57 and macrocyclic, 58–60 where the design of such systems is crucial in determining their properties. For example, linear ortho -linked multi-azobenzenes do not show any E -to- Z isomerization due to the inhibition of photochromism by ortho -substitution, or if they do, the rate of the Z -to- E thermal back reaction is on the order of milliseconds so must be observed by ultrafast transient absorption and flash photolysis experiments.…”