Visible-Light-Triggered Molecular Photoswitch Based on Reversible E/Z Isomerization of a 1,2-Dicyanoethene Derivative
Link to Publication: Angewandte Chemie International Publication
Contributing Authors: Xin Guo, Jiawang Zhou, Maxime Siegler, Art Bragg, Howard E. Katz
Date Published: February 23, 2015
A designed bis(dithienyl) dicyanoethene-based, strictly E/Z photoswitch (4TCE) operates through state-selective (E and Z isomer) photoactivation with visible light. The E and Z isomers of 4TCE exhibit remarkably different spectroscopic characteristics, including a large separation (70 nm) in their absorption maxima (λmax) and a 2.5-fold increase in molar extinction coefficient from cis to trans. The energetically stable trans form can be completely converted to the cis form within minutes when exposed to white light, whereas the reverse isomerization occurs readily upon irradiation by blue light (λ<480 nm) or completely by thermal conversion at elevated temperatures. These features together with excellent thermal stability and photostability of both isomers make this new E/Z photoswitch a promising building block for photoswitchable materials that operate without the need for UV light.