Synthesis and Photochemical Properties of Oligo-ortho-azobenzenes

Abstract

Azobenzenes have attracted great interest in recent years because of their ability to change conformation upon irradiation. This property has been featured in several applications not only in organic chemistry but also in biology. Even though monoazobenzenes have been extensively studied and documented in the literature, only a few methods are available for the synthesis of oligo-ortho-azobenzenes. Also, their photochemical properties have not been reported so far. This study shows an efficient strategy for the preparation of oligo-ortho-azobenzenes and the investigation of their photochemical properties. It is demonstrated that the absorption spectra are highly influenced by the substituents. Interestingly, none of the ortho-bis-, tris-, or tetra-azobenzenes showed any E → Z isomerization. Only the ortho-nitrogen-substituted monoazobenzenes' photochromic behavior upon UV irradiation was observed.

meta-Oligoazobiphenyls – synthesis via site-selective Mills reaction and photochemical properties

“…The number of possible isomers increases exponentially with the number of azo units. Additionally, it has been shown by others [14], as well as by us [15–17], that the direct connection of two azobonds to one aromatic ring alters the switching behavior considerably, such that bis- ortho -azobenzenes did not show any photochromicity. Therefore, in recent examples in the literature the azo-units have been dissected by incorporation of biphenyl units.…”

Synthesis, characterization, DNA binding and catalytic applications of Ru(III) complexes

“…13. Viscosity experimental results clearly showed that the relative viscosity of CT-DNA increases steadily on addition of increasing concentration of Ru(III) complexes (1)(2)(3)(4)(5). The increased degree of viscosity, which may depend on its affinity to DNA follows the order of 2 > 5 > 3 > 4 > 1.…”

“…The electronic spectra of all complexes (1)(2)(3)(4)(5) were recorded in dimethylformamide solvent in the range of 300-700 nm. The spectral data are listed in Table 2 and show in Fig.…”

“…This groove binding results in structural reorganization of CT-DNA which entails partial unwinding or damage of the double helix at the exterior phosphate backbone leading to the formation of a cavity to accommodate the complex [52]. The intrinsic binding constants (K b ) of all the ligands (HL 1 -HL 5 ) and Ru(III) complexes (1)(2)(3)(4)(5) with CT-DNA were determined (Eq. (1)) [53].…”

“…The widest usage of the azodyes is due to the number of the variations in the chemical structure and the methods of application which are generally not complex. Arylazo pyridine dyes generally have a high molar extinction coefficient, medium to high light and wash fastness properties [3]. In recent years, azodyes have attracted wide interest and found many uses in various fields such as dyeing of textile fibers, coloring of different materials, biological-medical studies, organic synthesis and advanced applications including optical storage capacity, optical switching, holography and non-linear optical properties [4,5].…”