A Study of the Photoorientation Phenomena in Cholesteric Polymer Systems Containing Photochromic Diarylethene Derivatives

Medvedeva, Dasha; Bobrovsky, Alexey; Boiko, N. I.; Shibaev, Valéry; Shirinyan, V. Z.; Krayushkin, M. M.

doi:10.1002/macp.200500513

Cited by 8 publications

(6 citation statements)

References 34 publications

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“…We synthesized perylene-labeled [28][29][30][31][32] HBPs with mesogenic shells [24][25][26] (1) as shown in Scheme 1 that could be dispersed in a nematic liquid crystal and studied the behavior of HBPs captured by disclinations using confocal fluorescence polarizing microscopy. 33,34 A perylene derivative with a methacryl group (2) was introduced to the HBP using photo-copolymerization.…”

Section: Methodsmentioning

confidence: 99%

Spatial distribution control of polymer nanoparticles by liquid crystal disclinations

Higashiguchi

Yasui

Ozawa

et al. 2012

Polym J

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A perylene-labeled hyper-branched polymer with a mesogenic shell was observed to migrate toward a field with a large distortion of directors. This polymer was captured by disclination lines of 1/2 strength in its nematic and chiral nematic phases using a confocal fluorescence microscope. In particular, the well-aligned particle array of the hyper-branched polymers was produced by the chiral nematic phase confined in a wedge cell. The hyper-branched polymer with its mesogenic shell was completely dissolved into an isotropic phase. Immediately after a phase transition to the chiral nematic phase, numerous droplets appeared over a wide area owing to phase separation, and the free droplets moved toward the disclination lines via Brownian motion. Finally, the droplets were rapidly attracted to the disclination lines and trapped within them. Polymer Journal (2012) 44, 632-638; doi:10.1038/pj.2012.44; published online 11 April 2012Keywords: confocal fluorescence polarizing microscope; disclination line; fluorescence; hyper-branched polymer; liquid crystal INTRODUCTION Controlling the spatial arrangements of molecules or particles on different length scales is one of the crucial issues of bottom-up nanotechnology. 1,2 Recently, dispersions of colloidal particles and polymers in nematic or cholesteric phases have attracted considerable attention because they demonstrate a diversity of self-assembled arrangements, such as linear or circle chains and 2D lattices. [3][4][5][6] The long-range force of self-assembly originates from the elastic energy of the distortions produced around the particles in the nematic phase. [7][8][9][10][11][12][13][14] The particles have also been observed to be attracted to and to migrate toward a disclination or domain boundary in the nematic field. Because the director distortions of nematic liquid crystals 15,16 are large near the disclination, the elastic energy is higher near the disclination than in uniform director regions. 3 The particles near the disclination might be exposed to an attractive force toward the disclination core, where the highest director gradient is formed.In terms of particle polymers, hyper-branched polymers (HBPs), a novel class of polymer with highly branched structures and large numbers of end groups, are attractive because dendritic chain structures can be produced via an one-pot reaction, and the chemical structure and molecular weight of HBPs can be easily modified. [17][18][19][20][21][22][23] Therefore, the physical properties of the HBPs, such as solubility to a host phase, molecular weight, viscosity, refractive index and fluorescence, can be easily controlled. If the spatial distribution and arrangement of HPBs are further controlled, the range of applications of these materials will expand extensively, especially in photonics and electronics.In this paper, we synthesize perylene-labeled HBPs with mesogenic shells (1) that can be dispersed in a nematic liquid crystal and study

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Section: Methodsmentioning

confidence: 99%

Spatial distribution control of polymer nanoparticles by liquid crystal disclinations

Higashiguchi

Yasui

Ozawa

et al. 2012

Polym J

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“…On the basis of these operating principles, several fluorophore−photochrome conjugates have already been synthesized, combining a diversity of fluorophores and photochromes within the same molecular assemblies. – In addition, these mechanisms have been reproduced intermolecularly – and extended to macromolecular constructs, – nanoparticles, – supramolecular assemblies, , and multilayer arrays . The main motivation behind these fundamental studies lies in the need to understand further the photochemical and photophysical properties of organic compounds while learning how to engineer photoresponsive materials based on molecular components.…”

Section: Introductionmentioning

confidence: 99%

“…Indeed, the operation of such probes in conjunction with multiphoton excitation schemes offers, in principle at least, the opportunity to break the diffraction barrier and push the resolution of fluorescence imaging down to the nanometer level. However, the vast majority of the fluorophore−photochrome assemblies developed so far are relatively hydrophobic and have been studied almost exclusively in organic solvents. – Strategies to impart hydrophilic character and biocompatibility to these functional molecular switches as well as methods to operate them efficiently in aqueous environments must be developed. Only then will these promising materials be able to evolve into valuable luminescent probes for practical applications in biology.…”

Section: Introductionmentioning

confidence: 99%

Photoswitchable Fluorescent Assemblies Based on Hydrophilic BODIPY−Spiropyran Conjugates

et al. 2008

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In search of strategies to design photoswitchable fluorescent probes and operate them in aqueous environments, we have envisioned the possibility of incorporating fluorescent, photochromic, and hydrophilic components within the same macromolecular construct. First, we synthesized a fluorophore-photochrome dyad, pairing a BODIPY fluorophore and a spiropyran photochrome in its molecular skeleton, and investigated the photochemical and photophysical properties of this compound in acetonitrile. Under these conditions, the photoinduced isomerization of the spiropyran causes a 56% decrease in the emission intensity of the BODIPY at the photostationary state. The photogenerated isomer has a lifetime of 2.7 × 10 2 s and reverts thermally to the original form, restoring the initial emission intensity. On the basis of these results, we copolymerized a similar BODIPY-spiropyran conjugate with a monomer bearing a pendant polyethylene glycol chain. The resulting polymer is soluble in aqueous environments, and its fluorescence can be modulated by operating the photochromic components with optical stimulation. Specifically, the emission intensity decreases by 40% at the photostationary state and reverts to the initial value after thermal reisomerization of the photochromic components. However, the lifetime of the photogenerated species in neutral buffer is significantly longer than that of the monomeric BODIPY-spiropyran in acetonitrile. The fluorescence of both monomeric and polymeric fluorophore-photochrome assemblies can be switched repeatedly between high and low values by alternating ultraviolet irradiation and storage in the dark. However, the fatigue resistance properties of both systems are relatively poor. In any case, our investigations demonstrate that our design is viable for the realization of hydrophilic and photoswitchable molecular assemblies. In principle, innovative fluorescent probes for biomedical applications can evolve from these studies, if methods to improve their fatigue resistance properties and optimize their reisomerization kinetics can be identified. † Part of the "Larry Dalton Festschrift".

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“…Dispersing the photochromic units into a polymer matrix is an easy and efficient strategy for preparing photochromic films. [58][59][60][61][62][63][64] So far, many photochromic diarylethene derivatives were embedded in various polymer matrices to investigate their performance and functions, for instance, bisthienylethene-bridged naphthalimide dimer 65 (shown in Scheme 1) dispersed in PMMA to demonstrate two-dimensional recording, bisbenzo-thienylethene-cored dendrimers 66 (Scheme 2) placed in polycarbonate of bisphenol A (PC) films to increase photocyclization conversion ratio, and diarylethene derivatives with perylene bisimide 67 (Scheme 3) dispersed in various rigid and soft polymer matrices to measure and analyze single-molecule photochromic reactions. These systems exhibit notable performances in solid state polymeric matrices.…”

Section: Photochromic Polymers Doped With Diarylethene Derivativesmentioning

confidence: 99%

Recent progress on photochromic diarylethene polymers

2011

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A Study of the Photoorientation Phenomena in Cholesteric Polymer Systems Containing Photochromic Diarylethene Derivatives

Cited by 8 publications

References 34 publications

Spatial distribution control of polymer nanoparticles by liquid crystal disclinations

Spatial distribution control of polymer nanoparticles by liquid crystal disclinations

Photoswitchable Fluorescent Assemblies Based on Hydrophilic BODIPY−Spiropyran Conjugates

Recent progress on photochromic diarylethene polymers

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