Further kinetic evidence for the competitive rotational and inversional Z-E isomerization of substituted azobenzenes

Abstract

Supplementary Material Available: Description of the X-ray diffraction determination of 3, including final atomic positional parameters (Tables 3 and 4), thermal parameters (Table 5), and selected bond distances and bond angles (Table 6), (6 pages); observed and calculated structure factors (Table 7) (12 pages). Ordering information is given on any current masthead page.

Azobenzene photoswitches for biomolecules

“…The rates are also solvent dependent, with many derivatives exhibiting an increase in thermal rate with increasing polarity, 16,30,36,37,42 although sometimes the opposite behaviour is observed. 43,44 Thermal rates are enhanced at low pH where protonation at the azo moiety reduces the activation barrier. 16,[45][46][47] The dipolar character of the thermal transition state is proposed to be similar to that of the excited state.…”

Multi-responsive fluorescence of amphiphilic diblock copolymer containing carboxylate azobenzene and N-isopropylacrylamide

“…This can be attributed to the poor solubility of the azobenzene block due to the protonation of carboxylic group in acid condition, which leads to inter/intra-molecular hydrogen bond and further induces tightly aggregated particles. Obviously, the inter/intra-molecular hydrogen bond of azo carboxylic acid is too strong to be destroyed by UV light irradiation [51,52]. In this case, the photoisomerization of azobenzene moieties can hardly take place due to this tight aggregate state, which provides relatively stable fluorescence intensity in acid condition.…”

Advances in understanding the photoresponsive behavior of azobenzenes substituted with strong electron withdrawing groups

“…Asano et al reported two different routes of thermal Z to E isomerization: inversion and rotation [31,32]. The inversion route proceeds through a linear transition state in which one of the nitrogen atoms is sp hybridized, whereas the rotation route involves a TS where the electrons of p bond are delocalized over the entire molecule and so the rotation around the remaining s bond is allowed.…”