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Cercosporin-Photocatalyzed [4+1]- and [4+2]-Annulations of Azoalkenes Under Mild Conditions
Published on: July 17, 2020
Photoswitchable basicity through the use of azoheteroarenes
Claire E Weston1, Robert D Richardson1, Matthew J Fuchter1
1Department of Chemistry, Imperial College London, London, SW7 2AZ, UK. m.fuchter@imperial.ac.uk.
Abstract:
Azoheteroarene photoswitches offer functional advantages over their more conventional azobenzene counterparts by virtue of their heteroaromatic ring(s). Here we report that azobis(2-imidazole) functions as a photoswitchable base due to the additional proton stabilisation that is possible in the protonated Z isomer, facilitated by the basic imidazole nitrogens. This thermodynamic difference in stability corresponds to a 1.3 unit difference in pK(a) values between the E and Z isomers. This pK(a) difference can be used to reversibly control solution pH.
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