2050-16-0Relevant articles and documents
Shape memory polyurethanes containing azo exhibiting photoisomerization function
Zhang, Yaoming,Wang, Chao,Pei, Xianqiang,Wang, Qihua,Wang, Tingmei
, p. 9976 - 9981 (2010)
A series of azobenzene-containing polyurethanes (azoPU) was synthesized. The structure of the azoPU and the synthesis process were detected by FTIR and nuclear magnetic resonance (NMR), and the transition temperature was determined by differential scanning calorimetry (DSC). Tensile and cyclic thermomechanical experiment results revealed that excellent mechanical properties, shape fixity (Rf), and shape recovery (Rr) were obtained by the addition of azo to the chain of PU. Rr and Rf of azoPU increased with the increase of hard segment (HS) content. The higher HS content enhanced interaction among polymer chains as the chances of induced dipole-dipole interaction between aromatic rings increased in the presence of azo in the main chain. The materials presented trans-cis isomerization under UV irradiation in addition to the shape memory effect. The UV-vis spectrum indicated that photoisomerization occurred both in solution and solid state. It is expected that the work may be helpful in expanding the application of shape memory PU in areas of drug release and optical data storage.
Functionalized azobenzene platinum(II) complexes as putative anticancer compounds
Samper, Katia G.,Lorenzo, Julia,Capdevila, Mercè,Palacios, òscar,Bayón, Pau
, p. 435 - 453 (2021)
The synthesis and characterization of four platinum(II) complexes using azobenzenes conveniently functionalized as ligands has been carried out. The characteristic photochemical behavior of the complexes due to the presence of azobenzene-type ligands and the role of the ligands in the activation of the complexes has been studied. Their promising cytotoxicity observed in HeLa cells prompted us to study the mechanism of action of these complexes as cytostatic agents. The interaction of the compounds with DNA, studied by circular dichroism, revealed a differential activity of the Pt(II) complexes upon irradiation. The intercalation abilities of the complexes as well as their reactivity with common proteins present in the blood stream allows to confirm some of the compounds obtained as good anticancer candidates.
Designing ternary Co-crystals with stacking interactions and weak hydrogen bonds. 4,4′-bis-hydroxyazobenzene
Chakraborty, Shaunak,Rajput, Lalit,Desiraju, Gautam R.
, p. 2571 - 2577 (2014)
Three ternary co-crystals of the title compound are reported. The design strategy hinges on the identification of a robust synthon with O-H...N hydrogen bonds in a binary co-crystal. Construction of this module allows the tuning of π...π stacking interactions and weak hydrogen bonds to incorporate the third component into the crystal structure. Screening of various co-formers showed that a delicate balance of electrostatics is required for stacking to favor the formation of ternaries. A C-H...N hydrogen-bonded motif was also found to occur repetitively in the ternary co-crystals. The directional nature of weak hydrogen bonds allows them to be used effectively in this study.
Synthesis and characterization of azobenzene-functionalized hyperbranched polymers
Alam, Md. Zahangir,Ogata, Tomonari,Kuwahara, Yutaka,Kurihara, Seiji
, p. 25 - 31 (2010)
Azobenzene functionalized hyperbranched polymers (HBAzPs) have been synthesized by polycondensation of 4,4'-di((2-hydroxyethoxy)azobenzene and 1,3,5-benzenetricarboxylic acid chloride in presence of triethylamine at room temperature through A2+B3 polymerization approach. The structure and properties of HBAzPs were characterized by 1H NMR, IR, GPC, DSC and UV-Visible spectrometry. Molecular weights as well as properties of HBAzPs were found to be greatly influenced by molar ratio of monomers, amount of triethylamine and monomer concentration. HBAzP solutions in THF showed absorbances at 356nm and 450nm corresponding to -* and n-* electronic transitions of azobenzene chromophores, respectively. A reversible trans-cis photoisomerization of HBAzPs was observed upon irradiation of UV and visible light. Taylor & Francis Group, LLC.
Rational design of a photoswitchable DNA glue enabling high regulatory function and supramolecular chirality transfer
Crespi, Stefano,Dohno, Chikara,Feringa, Ben L.,Kobauri, Piermichele,Kobayashi, Shotaro,Nakatani, Kazuhiko,Simeth, Nadja A.,Szymanski, Wiktor
, p. 9207 - 9220 (2021)
Short, complementary DNA single strands with mismatched base pairs cannot undergo spontaneous formation of duplex DNA (dsDNA). Mismatch binding ligands (MBLs) can compensate this effect, inducing the formation of the double helix and thereby acting as a molecular glue. Here, we present the rational design of photoswitchable MBLs that allow for reversible dsDNA assembly by light. Careful choice of the azobenzene core structure results in excellent band separation of theEandZisomers of the involved chromophores. This effect allows for efficient use of light as an external control element for duplex DNA formation and for an in-depth study of the DNA-ligand interaction by UV-Vis, SPR, and CD spectroscopy, revealing a tight mutual interaction and complementarity between the photoswitchable ligand and the mismatched DNA. We also show that the configuration of the switch reversibly dictates the conformation of the DNA strands, while the dsDNA serves as a chiral clamp and translates its chiral information onto the ligand inducing a preference in helical chirality of theZisomer of the MBLs.
Azobenzene-siloxane hybrids with lamellar structures from bridge-type alkoxysilyl precursors
Guo, Sufang,Chaikittisilp, Watcharop,Okubo, Tatsuya,Shimojima, Atsushi
, p. 25319 - 25325 (2014)
Lamellar azobenzene-siloxane hybrids were prepared by controlled hydrolysis and polycondensation of three types of precursors, where azobenzene is sandwiched by mono-, di- and triethoxysilyl groups using propylene linkers. All precursors underwent reversible and fast trans-cis isomerization upon UV/Vis irradiation in dilute solution. Upon hydrolysis of the triethoxysilylated precursor in a homogeneous solution under acidic conditions, precipitation occurred by self-assembly of hydrolyzed monomers into a lamellar structure. Although di- and mono-ethoxysilylated precursors produced less ordered products under identical conditions, highly ordered lamellar films were obtainable either by evaporation induced self-assembly of the hydrolyzed monomers or by solid-state reactions of precursor films. The degree of trans-cis isomerization of azobenzene moieties in the hybrid films was enhanced by decreasing the cross-linking degree of siloxane networks using precursors with less condensable alkoxy groups.
“Self-Lockable” Liquid Crystalline Diels–Alder Dynamic Network Actuators with Room Temperature Programmability and Solution Reprocessability
Han, Li,Jiang, Zhi-Chao,Xiao, Yao-Yu,Yin, Lu,Zhao, Yue
, p. 4925 - 4931 (2020)
Novel main-chain liquid crystalline Diels—Alder dynamic networks (LCDANs) were prepared that exhibit unprecedented ease for actuator programming and reprocessing compared to existing liquid crystalline network (LCN) systems. Following cooling from 125 °C, LCDANs are deformed with aligned mesogens self-locked at room temperature by slowly formed Diels–Alder (DA) bonds, which allows for the formation of solid 3D actuators capable of reversible shape change, and strip walker and wheel-capable light-driven locomotion upon either thermally or optically induced order–disorder phase transition. Any actuator can readily be erased at 125 °C and reprogrammed into a new one under ambient conditions. Moreover, LCDANs can be processed directly from melt (for example, fiber drawing) and from solution (for example, casting tubular actuators), which cannot be achieved with LCNs using exchangeable covalent bonds. The combined attributes of LCDANs offer significant progress toward developing easily programmable/processable LCN actuators.
Photoreversible Loading and Unloading of Q–Silsesquioxane Dynamic Network Sponges
Hu, Nai–hsuan,Furgal, Joseph Coy
, (2021)
The synthesis and mechanical properties of photoswitchable silsesquioxane/azobenzene hybrid 3D-polymers (“dynamic sponges”) are presented and discussed. The hybrid is capable of extensive macroscopic movement, and overcomes previously problematic crosslink locking issues. A hydride-functionalized Q-type silsesquioxane (Q8M8H) is reacted with di-allyloxyazobenzene using hydrosilylation methods. The properties of the resulting materials are controlled via careful choice of starting material ratios and solvent, leading to gels or films. Both morphologies show pronounced photoresponsive behavior in and on the surfaces of different solvents. Photoactuation is tracked by microscopy, dynamic mechanic analysis, and UV–vis spectroscopy. The gel system has a porous structure similar to a sponge. It undergoes shrinkage in volume by 18.3% in toluene under UV irradiation, and shows excellent recovery to the swollen state after irradiation with visible light. These novel photodynamic materials offer reversible modulus switching from 160?kPa in the swollen state to 500?kPa in the “wrung-out” sponge. The sponges can engage in uptake and release of a range of substances (i.e., reversible hydrophobic sponging), with overall performance determined by solvent specific quantities such as polarity and size. Such behavior gives these materials high potential for soft robotics applications and great promise as reusable environmental remediators.
New photochromic azoderivatives with potent acetylcholinesterase inhibition
Arroyo Ma?ez, Pau,Biscussi, Brunella,Murray, Ana Paula,Richmond, Victoria,Sequeira, Maria Alejandra
, (2021/06/12)
The design of photochromic cholinesterase inhibitors is a challenge of the photopharmacological approach towards the remote control of acetylcholinesterase (AChE) enzyme and its potential application in Alzheimer's disease therapy. In this work, a series of azoderivatives were designed, synthesized and evaluated as AChE inhibitors. The optimized microwave-assisted synthesis (two steps) showed excellent yields with a total reaction time no longer than 40 min. The results showed that all the synthesized compounds exhibited high AChE inhibitory activity at the micromolar range (IC50, 0.65–8.52 μM). Moreover, compound 19, with double four-hydrocarbon chain connected to piperidine, showed a powerful in vitro enzymatic response for its Z isomer (IC50: 0.43 μM) determined by Ellman's assay. Also, 19 showed a stable photostationary state monitored by UV/Vis absorption spectroscopy and 1H NMR spectra. These results indicate that 19 can act as an efficient photo-responsible probe to remote control AChE activity. Molecular modelling analysis of 19 Z revealed its affinity by the peripheral anionic site of AChE, providing understanding of its higher inhibition power. This study contributes to the development of new promising agents for photopharmacological treatment of Alzheimer's disease.