Synthesis and Photoinduced Anisotropy of Polymers Containing Nunchaku-Like Unit with an Azobenzene and a Mesogen

Abstract

A series of polymers containing nunchaku-like unit with an azo chromophore and a mesogen group was successfully prepared and photoinduced anisotropy of the obtained polymers was minutely investigated. Firstly, monomers containing nunchaku-like unit with an azo chromophore and a mesogen group linked by flexible group were synthesized. The structure of the monomers was confirmed via NMR COSY spectra. Subsequently, the obtained monomers were polymerized into corresponding polymers through RAFT polymerization. The prepared polymer samples were characterized through NMR, FTIR, gel permeation chromatography (GPC), and UV-vis testing while the thermal properties of the samples were investigated through differential scanning calorimeter (DSC) and thermogravimetric analysis (TGA) measurements. The photoinduced isomerization of the polymers, which was researched in situ via measuring UV-vis spectra of the polymer solutions and spin-coated films under irradiation with 450 nm light or putting in darkness, demonstrated the rapid trans-cis-trans isomerization of the polymers. When irradiated with a linearly polarized light, significant photoinduced birefringence and dichroism were observed, suggesting photoinduced isomerization of azobenzene can drive orientation of mesogen in the system. This study blazes a way to design the optical materials with light-controllable birefringence and dichroism.

Facile Synthesis of Self-Assembled NiFe Layered Double Hydroxide-Based Azobenzene Composite Films with Photoisomerization and Chemical Gas Sensor Performances

“…In addition, there is a statement that azobenzene dyes form modified materials with polymers through doping or cross-linking. This material has a large optical nonlinear coefficient and is widely studied and applied in the fields of optoelectronics. − Other research teams have studied and characterized the inclusion formation of Azo compounds and β-cyclodextrin at the air–water interface . Due to the photoisomerization of Azo dyes, their arrangement in polymers and a series of phenomena caused by photoisomerization have become the focus of research in recent years.…”

N-Alkylated Iminosugar Based Ligands: Synthesis and Inhibition of Human Lysosomal β-Glucocerebrosidase

“…To effect this the hydroxyl group of hydroxybenzoic acid was protected with a THP group under standard reaction conditions, giving compound 26 [ 54 ] which was then converted into benzoic ester 27 using 6-bromohexanol, PPh 3 and DIAD in THF. Removal of the THP group under acidic conditions provided known compound 28 [ 55 ]. Subsequent etherification under standard Mitsunobu conditions with 2-(2-azidoethoxy)ethanol [ 56 ] gave intermediate 29 .…”

“…After completed conversion of the starting material, the reaction mixture was filtered and the solvents were removed under reduced pressure. Purification on silica gel (cyclohexane-ethyl acetate 10:1) provided known compound 28 [ 55 ] (622 mg, 2.07 mmol, 75.8%) as a colourless wax. 1 H-NMR (300 MHz, CDCl 3 ) δ = 7.94 (d, 2 H, Ar), 7.76 (s, 1 H, OH), 6.92 (d, 2 H, Ar), 4.30 (t, 2 H, H-1´), 3.41 (t, 2 H, H-6´), 1.84-1.72 (m, 2 H, H-5´), 1.71-1.59 (m, 2 H, H-2´), 1.54-1.34 (po, 4 H, H-3´, H-4´); 13 C-NMR (75.5 MHz, CDCl 3 ) δ = 167.6 (OC = O), 161.0 (ipso), 132.0 (Ar), 122.0 (ipso), 115.5 (Ar), 65.1 (C-1´), 33.8 (C-6´), 32.7 (C-5´), 28.6 (C-2´), 27.9, 25.3 (C-3´, C-4´); MS: Calcd for [C 13 H 17 BrO 3 Na]: m/z 323.0259 [M + Na] + ; Found [M + Na] + 323.0258.…”

Absorption and Isomerization of Azobenzene Guest Molecules in Polymeric Nanoporous Crystalline Phases

“…Achieving fine control of these compounds' isomerization is important since they can be crucial components for the development of functional photoresponsive materials [55,56], light-powered molecular machines [57][58][59], and in photopharmacology [60], where spatiotemporal control of molecular transitions/reactions is needed. In particular, azobenzene, represents a very interesting example of molecular switch, its reversible trans→cis isomerization has been largely studied in solution [61], in the gas phase [62][63][64], as well as in amorphous and crystalline phases [65][66][67] and it is still actually investigated for many applications, from the development of active materials to the design of stimuli-responsive molecular systems and light-powered molecular machines [68][69][70].…”