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

• Published in: Beilstein journal of organic chemistry Vol. 16; no. 1; pp. 22 - 31
• Main Authors: Heindl, Andreas H, Wegner, Hermann A
• Format: Journal Article
• Language: English
• Published: Germany Beilstein-Institut zur Föerderung der Chemischen Wissenschaften 03.01.2020; Beilstein-Institut
• Subjects: Benzene; Chemistry; Chromatography; Full Research Paper; Hydrocarbons; Information storage; Investigations; Isomerization; Magnetic resonance spectroscopy; multistate photoswitches; NMR; Nuclear magnetic resonance; Oxidation; synthesis; tris(arylazo)benzene; synthesis; multistate photoswitches; tris(arylazo)benzene
• ISSN: 1860-5397; 2195-951X; 1860-5397
• DOI: 10.3762/bjoc.16.4

Multistate switches allow to drastically increase the information storage capacity and complexity of smart materials. In this context, unsymmetrical 1,3,5-tris(arylazo)benzenes - 'starazos' - which merge three photoswitches on one benzene ring, were successfully prepared. Two different synthetic strategies, one based on Baeyer-Mills reactions and the other based on Pd-catalyzed coupling reactions of arylhydrazides and aryl halides, followed by oxidation, were investigated. The Pd-catalyzed route efficiently led to the target compounds, unsymmetrical tris(arylazo)benzenes. These triple switches were preliminarily characterized in terms of their isomerization behavior using UV-vis and H NMR spectroscopy. The efficient synthesis of this new class of unsymmetrical tris(arylazo)benzenes opened new avenues to novel multistate switching materials.