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General Principles for the Design of Visible‐Light‐Responsive Photoswitches: Tetra‐ ortho ‐Chloro‐Azobenzenes
Author(s) -
Lameijer Lucien N.,
Budzak Simon,
Simeth Nadja A.,
Hansen Mickel J.,
Feringa Ben L.,
Jacquemin Denis,
Szymanski Wiktor
Publication year - 2020
Publication title -
angewandte chemie
Language(s) - English
Resource type - Journals
eISSN - 1521-3757
pISSN - 0044-8249
DOI - 10.1002/ange.202008700
Subject(s) - tetra , photochemistry , nanotechnology , rational design , visible spectrum , materials science , design elements and principles , absorption (acoustics) , molecule , computer science , combinatorial chemistry , chemistry , optoelectronics , organic chemistry , software engineering , medicinal chemistry , composite material
Molecular photoswitches enable reversible external control of biological systems, nanomachines, and smart materials. Their development is driven by the need for low energy (green‐red‐NIR) light switching, to allow non‐invasive operation with deep tissue penetration. The lack of clear design principles for the adaptation and optimization of such systems limits further applications. Here we provide a design rulebook for tetra‐ortho‐chloroazobenzenes, an emerging class of visible‐light‐responsive photochromes, by elucidating the role that substituents play in defining their key characteristics: absorption spectra, band overlap, photoswitching efficiencies, and half‐lives of the unstable cis isomers. This is achieved through joint photochemical and theoretical analyses of a representative library of molecules featuring substituents of varying electronic nature. A set of guidelines is presented that enables tuning of properties to the desired application through informed photochrome engineering.