Photochromic and nonlinear optical properties of azo-functionalized POSS nanoparticles dispersed in nematic liquid crystals

Yang

2015

Chemistry A European J

Mono- and octa-azobenzene-functionalized cage silsesquioxanes were easily synthesized by the reaction of 4-bromoazobenzene with monovinyl-substituted octasilsesquioxane and cubic octavinylsilsesquioxane through the Heck coupling reaction. Excited-state energies obtained from time-dependent density functional theory (TDDFT) and the CAM-B3LYP functional correlate very well with experimental trans-cis photoisomerization results from UV/Vis spectroscopy. These azobenzene-functionalized cages exhibit good thermal stability and are fluorescent with maximum emission at approximately 400 nm, making them potential materials for blue-light emission.

Section: Resultsmentioning

confidence: 59%

Section: Introductionmentioning

confidence: 99%

Azobenzene‐Functionalized Cage Silsesquioxanes as Inorganic–Organic Hybrid, Photoresponsive, Nanoscale, Building Blocks

Yang

2015

Chemistry A European J

“…We prepared two such structures POSS-BAFKU and POSS-BAFK and dissolve them (1.5 % w/w) in a nematic liquid crystal (Δn = 0.34) as described in our recent paper [29]. Such nanoparticles are well soluble in liquid crystal and form homogenous mixture.…”

Section: Liquid Crystal With Azofunctionalized Poss Nanoparticlesmentioning

confidence: 98%

“…However, investigated azo-polymers are different and their behavior under the same illumination conditions can differ depending on specific material properties and chemistry (type of bonds, way of substitutions and different azo-chromophores) involved. Various groups of materials containing azo-benzene derivative molecules have also been investigated including glasses [13], liquid crystalline polymers [14,15], biopolymers [16][17][18][19], liquid crystals [20][21], Langmuir-Blodgett-Kuhn structures [22,23], layer-by-layer films [ 24,25] monolayers [26,27] and even nano-objects [28,29]. Particularly interesting is light-induced macroscopic polymer mass transport discovered initially for azo-substituted polymers [30,31].…”

Section: Introductionmentioning

confidence: 99%

Laser inscription of surface structures and induction of optical anisotropy in azo-benzene substituted photochromic polymers and other systems

et al. 2014

Self Cite

We present trial calculations of surface light-induced patterns in photochromic azo-substituted polymers. Using microscope with nanopositioning stage various birefringence and surface structures have been recorded in photochromic azo-functionalized polymers. By systematic approach to the inscription experiment and controlling cw or pulsed laser light intensity, its polarization and beam scan speed we observed the dynamics of molecular photoorientation and its relation to mass transport. We discuss properties of holographically inscribed polarization gratings and analyze them spatially by monitoring of microscopic local diffraction efficiency. We report how azo-benzene molecules can work in other systems, i.e. azobenzene functionalized POSS molecules embedded in nematic liquid crystal.

Organic Photonics and Photovoltaics

“…100 [150]. These nanoparticles and nematic liq- Unlike the analog with a thiophene linker [151] metaphenyl-linked diarylethene of this type exhibits lightcontrolled reversible conduction on the gold surface [152].…”

Section: Scheme 99mentioning

confidence: 99%

Nanophotochromism

Barachevsky¹

2015

Abstract:The review presents the state-of-the-art analysis of investigations in the field of a new line of research of photochromism -nanophotochromism. The design, properties, and possible applications of photochromic nanoparticles prepared by different methods with the use of photochromic substances (aggregates, host-guest, and polymer systems, solid nanoparticles) as well as core-shell photochromic nanostructures based on polymers, silica, quantum dots, doped upconversion nanocrystals, and Ag, Au, etc. nanoparticles have been reviewed. Keywords: photochromism; photochromic nanoparticles; core-shell photochromic nanoparticles design; photoswitching; aggregates; polymer systems, host-guest systems IntroductionPhotochromism is a very important phenomenon for different applications in photonics. The applications are based on reversible phototransformations of photochromic compounds between two states and changes of their properties that accompany these transformations At present, systems and materials containing photochromic nanopatricles have become highly significant. Among these are nanodimensional particles of photochromic substances, including aggregates, and coreshell systems. As a core, inorganic nanoparticles of gold, silver, metal oxides, quantum dots (QD), and also polymeric nanoparticles are used. The shell consists of photochromic molecules or their aggregates connected to a core surface either chemically or physically. Photochromic nanoparticles with photocontrolled fluorescence arouse a special interest because the fluorescence technique is becoming a leading strategy in biological diagnosis, imaging, and detection applications. This paper is a state-of-the-art review which presents results of studying photochromic nanoparticles including author's own data. The results of earlier research are also surveyed in some other reviews [1][2][3][4][5][6][7][8][9][10][11][12][13]. Photochromic nanoparticles:properties and applications Nanoparticles based on photochromic substances AggregatesThe most known photochromic nanoparticles are aggregates of photochromic organic compounds [14]. These compounds experience reversible photoinduced transformations between two states, Sch. 1A and Sch. 1B. Scheme 1The photoinduced colored merocyanine form B absorbing visible irradiation is formed from a colorless form A as a result of photodissociation of the -C-O-bond of the pyran heterocycle under UV radiation, and this is followed by spontaneous isomerization of the cis-form to the trans one. The colored form B can be converted back to the initial colorless form A upon absorption of visible light or spontaneously during the dark relaxation, which is accelerated by heating.The J-aggregates of nitro-substituted indoline spiropyrans Sch. 2 with long alkyl substituents are of special interest [15].The narrow absorption bands of J-aggregates of these photochromic compounds (Fig. 1) made it possible prepare a specimen of the multilayered optical disk providing freUnauthenticated Download