Starazo triple switches – synthesis of unsymmetrical 1,3,5-tris(arylazo)benzenes

• Andreas H. Heindl and
• Hermann A. Wegner

Beilstein J. Org. Chem. 2020, 16, 22–31, doi:10.3762/bjoc.16.4

• characterized in terms of their isomerization behavior using UV–vis and 1H NMR spectroscopy. The efficient synthesis of this new class of unsymmetrical tris(arylazo)benzenes opened new avenues to novel multistate switching materials. Keywords: multistate photoswitches; synthesis; tris(arylazo)benzene

• Dreuw and co-workers, who suggested tris(arylazo)benzene 2 (Figure 1) to feature spectrally separated absorption bands for each AB branch. The authors could show that the excited states of the AB branches in tris(arylazo)benzenes were electronically decoupled, despite the spatial overlap. Hence, only

• -hydrazide (12, Scheme 4). The reaction yielded the intermediate 13 in 58% yield, using slightly modified conditions compared to the literature protocol [10]. The CuI-mediated oxidation of the bis(arylhydrazide) 13 afforded the desired tris(arylazo)benzene 14 in only 19% yield, which was significantly lower