Synthesis and photochromism of catechol-containing symmetrical azobenzene compounds

Abstract

Symmetrical azobenzene derivatives with two catechol groups, 1d–4d, were synthesized as kinds of novel compounds, and the structures were confirmed using mass spectrometry and nuclear magnetic resonance spectroscopy. These compounds could attain photostationary state rapidly in solution upon UV irradiation, and their photochromism had good reversibility. Substituents and their positions on azobenzene chromophore had obvious influence on the maximum absorption and photochromic performances of these as-synthesized compounds. Electron-donating group on ortho positions could contribute to the redshift π–π* band. The sulfonamide group that is bonded to dopamine molecules and azobenzene rings caused a negligible n–π* transition of cis isomer, resulting in photobleaching upon UV irradiation. Among the four compounds, 4d had the strongest electron-donating ortho -methoxy substituents and lower planarity; thus its absorption could decrease more significantly upon UV irradiation of the same intensity, and its cis -to- trans conversion could be up to 63%. Furthermore, owing to the presence of catechol groups, 4d showed an effective affinity and adhesion to substrate, and on the surface of substrate, a weak colour change could be observed upon UV irradiation, but the reversibility was poorer than that in solution.

Azobenzene-Containing Schiff-Bases—Syntheses and Dyes Applications

“…Ege Hosgor et al [45] reduced the nitro group of the aromatic ring to an amino group by Pd/C catalytic reduction followed by CuBr-catalyzed azo coupling to synthesize azo compounds. Suju Fan et al [46] synthesized azobenzene compounds from aromatic compounds with amino groups by NaClO, while Subhas Samanta et al [47] used AgO as catalyst. Alford Antoine John et al [48] synthesized azo compounds in dichloromethane solution.…”

“…This solution was mixed with 3-amino phenol (44) in the presence of sodium hydroxide solution to give an azo compound with an amine group (45). This was dissolved in ethanol, and 4-(dimethylamino)benzaldehyde (46) and glacial acetic acid were added and refluxed at 80 • C for several hours. As a result, an azobenzene Schiff base with an amine (47) at the phenyl on the azo group side and an aldehyde bound from the outside was obtained.…”

One-Dimensional Chain Viologen-Based Lanthanide Multistimulus-Responsive Materials with Photochromism, Photoluminescence, Photomagnetism, and Ammonia/Amine Vapor Sensing

“…Synthesis and applications of such materials are evolving quickly and remain an active area of study. − On account of structural and functional diversity, coordination polymer (CP) materials, as is well known, have been widely studied in this research domain. The flexible organic ligands are commonly used to create chromic CP materials that are responsive to various stimuli, which involve bipyridine derivatives, − diarylethene derivatives, − azobenzene derivatives, − spiropyrans, , and so forth. One of the popular building blocks for the creation of multistimulus-responsive chromic CPs is viologen and its derivates, − which belongs to the bipyridine derivatives.…”