Photo-Electroswitchable Arylaminoazobenzenes

Authors

Carl Jacky Saint-Louis, Kennesaw State University
David J. Warner, Department of Chemistry & Biochemistry, The University of Alabama, Tuscaloosa, Alabama 35487, United States.
Katie S. Keane, Department of Chemistry & Biochemistry, The University of Alabama, Tuscaloosa, Alabama 35487, United States.
Melody D. Kelley, Department of Physical Science, Perimeter College at Georgia State University, Atlanta, Georgia 30303, United States.
Connor M. Meyers, Department of Chemistry & Biochemistry, The University of Alabama, Tuscaloosa, Alabama 35487, United States.
Silas C. Blackstock, Department of Chemistry & Biochemistry, The University of Alabama, Tuscaloosa, Alabama 35487, United States.

Department

Chemistry and Biochemistry

Document Type

Article

Publication Date

9-3-2021

Abstract

Azobenzenes appended with a redox-active arylamino group (redox auxiliary, RA) are prepared and shown to undergo fast, complete, and catalytic → azo isomerization upon electron loss from the RA unit of the azobenzene. The RA-azo structures can be reversibly (→→) cycled by sequential photo- and electrostimulation. Due to the robust nature of the RA-azo radical cation chain carrying species, initiation of electron transfer (ET) catalysis occurs at low levels (1.0-0.04 mol %) of catalytic loading and is effective even at -RA-azo concentrations of 10-10 M, yielding TONs (turnover numbers) of 100-2300 under such dilute conditions. The RA-azo → conversion is demonstrated using chemical oxidation (redox switching), electrochemical oxidation (electro switching), and photochemical oxidation (photoredox switching). The → acceleration is shown to be at least 2 × 10-fold for RA-azo . DFT calculations on methyl yellow suggest that a N-centered radical cation of the RA group stabilizes the → N-N twist transition state of the RA-azo, yielding a large reduction in the barrier for RA-azo compared to neutral RA-azo. The RA-azo structure class has nanomechanical features that can be toggled with photo- and electrostimulation, the latter offering a quick switch for complete Z→E conversion.

Journal Title

The Journal of organic chemistry

Volume

86

Issue

17

First Page

11341

Last Page

11353

Digital Object Identifier (DOI)

10.1021/acs.joc.1c00763