Three photoresponsive bis(crownethers) with an azo-linkage (2)–(4) were synthesised for the purpose of controlling ion extraction and ion transport by an on-off light swith. The compound trans-(2), in which azobenzene is linked with two monoaza-15-crown-5 compounds via an amide linkage, extracted K+ and Rb+ in 6.7% and 0.5%, respectively, whereas the extractive abilities (ex%) of photoisomerised cis-(2)
nitrogen atoms from the ligand and three oxygen atoms from two nitrate ions. The dinuclear zinc complexcontaining the azobenzene chromophore was photoisomerizable between the trans and cis forms. The binding affinities of the trans and cis complexes with calf thymus (CT)-DNA were similar. Although the DNA cleavage activity of the trans complex was negligible, the cis complex was able to cleave DNA
Light-Regulated Molecular Trafficking in a Synthetic Water-Soluble Host
作者:Jesús del Barrio、Seán T. J. Ryan、Pablo G. Jambrina、Edina Rosta、Oren A. Scherman
DOI:10.1021/jacs.5b11642
日期:2016.5.11
Cucurbit[8]uril (CB[8])-mediated complexation of a dicationic azobenzene in water allows for the light-controlled encapsulation of a variety of second guest compounds, including amino acids, dyes, and fragrance molecules. Such controlled guest sequestration inside the cavity of CB[8] enables the regulation of the thermally induced phase transition of poly(N-isopropylacrylamide)-which is not photosensitive-thus
A bis(boronic acid)-based saccharide receptor (1) bearing a photoresponsive azobenzene moiety has been synthesised, aiming at the photocontrol of the saccharide-binding properties by the distance change between the two boronic acids. trans-1 is wholly CD-silent in the presence of various saccharides whereas cis-1 yielded CD-active species with D-glucose and D-allose in aqueous pH 10.5 solution and with D-glucose in methanol. The findings indicate that the two boronic acids in cis-1 can act cooperatively to selectively recognise these saccharides by the formation of the cyclic 1∶1 complexes. cis-to-trans thermal isomerisation slowly takes place in methanol (ko = 2.1 × 10–6 s–1) but the rate is extremely slow in aqueous pH 10.5 solution (half-life 8.7 days). In methanol the rate is retarded only by D-glucose which forms a macrocyclic 1∶1 complex with cis-1. In aqueous pH 10.5 solution the cis-to-trans isomerisation could be induced virtually only by visible-light irradiation, indicating that this system is useful as a light-gated saccharide receptor.
Regulating Copper-Binding Affinity with Photoisomerizable Azobenzene Ligand by Construction of a Self-Assembled Monolayer
作者:Isao Takahashi、Yuichiro Honda、Shun Hirota
DOI:10.1002/anie.200902048
日期:2009.8.3
Catch and release! Self‐assembled monolayers (SAMs) of both trans‐ and cis‐azobenzeneligands can bind CuII ions. Ions bound to the trans ligand are released by cyclic voltammetry (CV) redox scans whereas those bound to the cis ligand are not (see picture). Irradiation of the cis‐SAM with visible light leads to removal of the bound Cu ions by cis‐to‐trans photoisomerization.