Beilstein J. Org. Chem.2025,21, 830–838, doi:10.3762/bjoc.21.66
discovered that simple acylation of the pyrazole moiety leads to increased quantum yields of isomerization, long Z-isomer life-times, good spectral separation, and high photostability.
Keywords: azobenzenes; azopyrazoles; photochromism; photoswitches; substituent effects; Introduction
Organic photoswitches
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Graphical Abstract
Scheme 1:
Reaction pathway for synthesizing NH-substituted, methylated-, and acetylated arylazopyrazoles. Con...
Beilstein J. Org. Chem.2019,15, 2753–2764, doi:10.3762/bjoc.15.266
measurements of representative examples, we demonstrate that ortho-benzene substitution of the arylazopyrazoles drastically increases the Z-isomer stability and allows further tuning of their addressability. This includes the discovery of new azopyrazoles with a Z-isomer thermal half-life of ≈46 years. Such
-life (t1/2 = 74 days at 25 °C). The photochemical addressability of the azopyrazoles can further be complemented by other stimuli, for example chemical switching using acid [19]. Given their excellent performance, arylazopyrazoles are replacing azobenzenes in optically addressable applications
including imaging applications [20], photopharmacology [21], supramolecular chemistry [22][23], responsive foams [24], coordination chemistry [25] and DNA nanotechnology [26][27].
Whilst the azopyrazoles have excellent properties for use in a variety of photo-addressable applications, it remains frustrating
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Graphical Abstract
Figure 1:
a) Tetra ortho-substituted azobenzenes represent a significant advance in terms of Z-isomer stabili...