Control over molecular motion using thecis–transphotoisomerization of the azo group

Abstract

SummaryControl over molecular motion represents an important objective in modern chemistry. Aromatic azobenzenes are excellent candidates as molecular switches since they can exist in two forms, namely the cis (Z) and trans (E) isomers, which can interconvert both photochemically and thermally. This transformation induces a molecular movement and a significant geometric change, therefore the azobenzene unit is an excellent candidate to build dynamic molecular devices. We describe selected examples of systems containing an azobenzene moiety and their motions and geometrical changes caused by external stimuli.

Tuning the optical emission of MoS2 nanosheets using proximal photoswitchable azobenzene molecules

“…[14][15][16] For instance, chemisorbed, highly ordered azobenzene self-assembled monolayers (SAMs) are widely known to photoisomerize between trans and cis conformations. 17,18 Among various tunable properties of SAMs, which serve as the basis for sensors, 19 memory devices, 17,20 and organic thin-film transistors, 21 the quantum efficiency of a semiconductor in intimate contact can also be tuned. Therefore, heterostructures made by sandwiching SAMs between a metallic film and a monolayer of a 2D crystal are expected not only to tune the electronic properties of the 2D materials, as demonstrated previously by Margapoti et al, 22 but also to optically modulate their spectroscopic properties.…”

Molecular Design of Light-Responsive Hydrogels, For in Situ Generation of Fast and Reversible Valves for Microfluidic Applications

“…22 Various photochromes have been studied that exhibit lightinduced isomerization e.g. azobenzenes 23,24 and spiropyrans (Sp). 1 Azobenzenes isomerize from their trans to cis conformation with an accompanying relatively small change of dipole moment and molecular dimensions.…”

Stimuli-responsive Cooperative Catalysts Based on Dynamic Conformational Changes toward Spatiotemporal Control of Chemical Reactions

“…11,12 Rebek et al reported a photoresponsive cooperative catalyst utilizing adenine receptors. 11 An azobenzene core is introduced to the catalyst 1 to induce reversible overall conformational changes based on photoisomerization of azobenzene, 13,14 and two imide-based adenine receptors 15 are connected to the core to capture reactants containing an adenine unit ( Figure 4). Irradiation of 366 nm light induces isomerization of the transazobenzene core to the cis-form to afford a 1:1 mixture of cisand trans-azobenzene isomers of the catalyst at the photostationary state.…”