Showing papers by "Quan Li published in 2013"
TL;DR: The observation of considerably lengthy individual supramolescular polymer molecules indicates that the molecular self-assembly in water by non-covalent host-guest molecular recognition is sufficiently strong to form the supramolecular polymer.
Abstract: A light-driven, linear, chiral supramolecular polymer was constructed in water by host–guest molecular recognition between bis(p-sulfonatocalix[4]arene) and the α-cyclodextrin-based pseudo[3]rotaxane containing axially chiral 1,1′-binaphthyl and photoresponsive azobenzene moieties. The successful supramolecular polymerization by non-covalent host–guest molecular recognition was confirmed by 1H NMR spectroscopy and dynamic light scattering (DLS) measurements, and its photoresponsive behavior was investigated by UV–vis absorption spectroscopy, scanning electron microscopy (SEM), atomic force microscopy (AFM), and transmission electron microscopy (TEM). The chirality of this supramolecular polymer was confirmed by circular dichroism spectroscopy. The dramatic morphology change of this chiral polymer driven by light was observed in SEM, AFM and TEM images. More interestingly, dynamically self-assembled, light-driven, single-helical linear supramolecular polymer molecules with lengths of hundreds of nanometers...
234 citations
23 Sep 2013
TL;DR: In this paper, anion-driven Supramolecular self-assembled materials from self-assembly of Rigid Flexible Block Molecules are described. But the authors focus on self-folding materials.
Abstract: Preface vii Contributors ix 1 Nature-Inspired Stimuli-Responsive Self-Folding Materials 1 Leonid Ionov 2 Stimuli-Responsive Nanostructures from Self-Assembly of Rigid Flexible Block Molecules 17 Yongju Kim, Taehoon Kim, and Myongsoo Lee 3 Stimuli-Directed Alignment Control of Semiconducting Discotic Liquid Crystalline Nanostructures 55 Hari Krishna Bisoyi and Quan Li 4 Anion-Driven Supramolecular Self-Assembled Materials 115 Hiromitsu Maeda 5 Photoresponsive Cholesteric Liquid Crystals 141 Yannian Li and Quan Li 6 Electric- and Light-Responsive Bent-Core Liquid Crystals: From Molecular Architecture and Supramolecular Nanostructures to Applications 189 Yongqiang Zhang 7 Photomechanical Liquid Crystalline Polymers:Motion in Response to Light 233 Haifeng Yu and Quan Li 8 Responsive Nanoporous Silica Colloidal Films and Membranes 265 Amir Khabibullin and Ilya Zharov 9 Stimuli-Responsive Smart Organic Hybrid Metal Nanoparticles 293 Chenming Xue and Quan Li 10 Biologically Stimuli-Responsive Hydrogels 335 Akifumi Kawamura and Takashi Miyata 11 Biomimetic Self-Oscillating Polymer Gels 363 Ryo Yoshida 12 Stimuli-Responsive Surfaces in Biomedical Applications 377 Alice Pranzetti, Jon A Preece, and Paula M Mendes 13 Stimuli-Responsive Conjugated Polymers: From Electronic Noses to Artificial Muscles 423 Astha Malhotra, Matthew McInnis, Jordan Anderson, and Lei Zhai Index 471
178 citations
TL;DR: A new light-driven chiral molecular switch doped in a stable blue phase (BP) liquid crystal allows wide optical tunability of three-dimensional cubic nanostructures with a selective reflection wavelength that is reversibly tuned through the visible region.
Abstract: A new light-driven chiral molecular switch doped in a stable blue phase (BP) liquid crystal allows wide optical tunability of three-dimensional cubic nanostructures with a selective reflection wavelength that is reversibly tuned through the visible region. Moreover, unprecedented reversible light-directed red, green, and blue reflections of the self-organized three-dimensional cubic nanostructure in a single film are demonstrated for the first time. Additionally, unusual isothermal photo-stimulated less ordered BP II to more ordered BP I phase transition was observed in the system.
151 citations
TL;DR: Three compounds that bear two axially chiral bridged binaphthyl units were developed as photodynamic chiral dopants for nematic liquid crystals by inducing a change in the dihedral angle that led to an inversion of the handedness of the helices.
Abstract: A good turn: Three compounds that bear two axially chiral bridged binaphthyl units were developed as photodynamic chiral dopants for nematic liquid crystals. For compounds with suitable bridge lengths, a change in the dihedral angle induced a switch of the binaphthyl units from the cisoid to the transoid form upon UV irradiation, which led to an inversion of the handedness of the helices.
117 citations
TL;DR: A design strategy based on the chiral conflict and equilibrium shifting between multiple chiral moieties in a single molecule is reported, holding great potential for the development of smart stimuli-responsive materials for future applications, especially in the areas in which CPL is involved.
Abstract: Stimuli-directing self-organized supramolecular architectures with tailored functional groups have proven important for the design of intelligent molecular devices. Light-driven induction of helicity and inversion of handedness in self-organized helical superstructures, that is, cholesteric liquid crystals (CLCs) have the unique property of selective reflection of circularly polarized light (CPL) and the advantages of remote, spatial, and temporal controllability. Such systems might be achieved by doping photoresponsive chiral molecules into an achiral nematic liquid-crystal (LC) host to self-organize into an optically tunable helical superstructure. However, to date, the photoresponsive chiral dopants capable of inducing light-driven handedness inversions in self-organized helical superstructures mainly depend on chance, that is, it is not predictable for a photoresponsive chiral molecule to induce handedness inversion driven by light. Compared with the intensive studies on the optically tunable helical superstructures without handedness inversion, 4] developing novel photoresponsive chiral dopants capable of inducing lightdriven handedness inversion in a self-organized helical superstructure, that is, reversibly tuning the handedness between left-handed and right-handed, still remains a challenging task. Nevertheless, controlling the chirality with helix inversion in a helical superstructure is associated with the handedness inversion of CPL that it reflects, holding great potential for the development of smart stimuli-responsive materials for future applications, especially in the areas in which CPL is involved. A few examples of handedness inversion in self-organized helical superstructures have been demonstrated with photoresponsive chiral dopants. These systems require that the dopants either reverse their intrinsic chirality (e.g., sterically overcrowded alkenes) or switch between two isomers with dramatically different conformations (e.g., transoid and cisoid forms of binaphthyls) that can promote the helix inversion. 10, 12] Their disadvantages include low helical twisting powers (HTPs) of dopants, 12] the requirement of specific LC hosts, 10, 12] or very delicate syntheses. 9] More importantly, it is difficult to predict which system will induce helix inversion because of the subtle interplay of contributions from the molecular conformation change upon light irradiation and the dopant–host interactions. Rational design of photoresponsive molecules for handedness inversion would be of great interest and would significantly broaden their applications. Herein, we report a design strategy based on the chiral conflict and equilibrium shifting between multiple chiral moieties in a single molecule. A series of azoarene molecules (S,R,S)-1 a–c, bearing axially chiral binaphthyl units of opposite chiral configurations (Figure 1), were
90 citations
TL;DR: In this article, the effect of doped gold nanoparticles on perylene diimide (PDI) dye molecules was investigated by UV vis, fl uorescence, transmission electron microscopy, scanning electron microscope, and Raman experiments.
Abstract: : Organo-soluble decane thiol monolayer-protected gold nanoparticles of different shapes and sizes are homogenously mixed with strong fl uorescent perylene diimide (PDI) dye molecules in both solution and solid states. The effect of the doped gold nanoparticles on PDI is investigated by UV vis, fl uorescence, transmission electron microscopy, scanning electron microscopy, and Raman experiments. The gold nanoparticles are found to modify the strong fl uorescence properties of PDI depending on particle size and shape. The smallest spherical gold nanoparticles (2.6 nm) exhibit the strongest quenching effect. When the smallest spherical gold nanoparticles are cast on the PDI soaked paper followed by drying and/or sealing in a polydimethylsiloxane fi lm, the area with gold nanoparticles shows signifi cant quenching effects under a UV light but appears visually identical to the surrounding area under daylight. This demonstrates the potential to introduce gold nanoparticles into practical applications such as antifraud technologies.
73 citations
TL;DR: In this article, a chiral dithienylperfluorocyclopentene molecule bearing two bridged binaphthyl units was designed and synthesized by a Suzuki-Miyaura cross-coupling reaction.
Abstract: A chiral dithienylperfluorocyclopentene molecule bearing two bridged binaphthyl units was designed and synthesized by a Suzuki–Miyaura cross-coupling reaction between chiral binaphthyl iodide and dithienylperfluorocyclopentene-derived bis(boronic ester). Its photoresponsive properties were investigated in both organic solvent and liquid crystal media. The UV-vis spectra exhibited typical photochromic changes of diarylethenes upon UV irradiation. The CD spectral changes upon light irradiation indicated that the conformation of binaphthyl units and the chiroptical properties of this molecule could be modulated by light. More importantly, when using as a chiral dopant in nematic liquid crystals, this molecule could induce cholesteric liquid crystals with very high helical twisting powers. At very low doping concentrations, this dopant was able to induce a reversible isothermal phase transition between nematic and cholesteric phases upon light irradiation. The photochemical control of the pitch length of cholesteric phases at higher doping concentrations enabled the reversible reflection wavelength control in the visible region. Superior thermal stability and excellent fatigue resistance were also observed during the photoswitching process, which are important properties for applications.
45 citations
TL;DR: In this article, three terminal thiols possessing azobenzene and perylene diimide (PDI) segments covalently linked by alkylene spacers of different lengths (PnSH, n = 4, 6, and 8) were synthesized to stabilize and functionalize gold nanorods (GNRs) via strong covalent Au-S bonds onto the gold surface.
Abstract: Three terminal thiols possessing azobenzene and perylene diimide (PDI) segments covalently linked by alkylene spacers of different lengths (PnSH, n = 4, 6, and 8) were synthesized to stabilize and functionalize gold nanorods (GNRs) via strong covalent Au–S bonds onto the gold surface. The resulting hydrophobic thiol monolayer-protected GNRs (PnGNRs) were stable in both organic solvent and the solid state and exhibited fascinating photoresponsive self-assembly behavior. The PDI moieties provided π–π interactions to promote GNR self-assemblies while the photoresponsive azobenzene moieties offered a way to phototune the assemblies in a reversible manner. Interestingly, when PnGNRs were mixed with a structurally similar room-temperature thermotropic liquid-crystal perylene diimide (LCP), the UV-irradiated PnGNRs showed more compatibility with the LCP host than their corresponding unirradiated ones. Furthermore, the PnGNRs with varied alkylene chain lengths showed different dispersion abilities in LCP. The UV-...
25 citations
TL;DR: Porphyrin metal (Zn, Cu, and Mg) complex monolayer-protected gold nanorods (GNRs) were synthesized and exhibited distinct spectroscopic properties and were able to self-assemble into side-by-side arrays driven by π-π intermolecular interactions of the surface metal porphyr in chromophores.
24 citations
TL;DR: The preparation and characterization of gold nanorods protected by a hydrophilic cucurbit[7]uril-based-pseudorotaxane anchored monolayer are reported, which are water-soluble as well as stable in both solution and the solid state.
Abstract: : Cucurbit[n]uril-based rotaxane or pseudorotaxane devices connected to gold electrode surfaces and spherical gold nanoparticles have previously been developed. Herein, we report the preparation and characterization of gold nanorods (GNRs) protected by a hydrophilic cucurbit[7]uril-based-pseudorotaxane anchored monolayer. The resulting GNRs decorated with both cucurbit[7]uril-based pseudorotaxane disulfide and sodium thioctate on their entire surface through covalent S Au linkages are water-soluble as well as stable in both solution and the solid state.
15 citations
TL;DR: In this paper, the authors synthesize a hybrid gold nanorod with mercaptosuccinic acid (MSA) and carboxylic acid modified single-wall carbon nanotubes (CNT-COOH) to self-aggregate.
Abstract: Hydrophilic mercaptosuccinic acid (MSA) monolayer-protected gold nanorods (GNRs) were synthesized. The resulting GNRs encapsulated with biocompatible MSA molecules via covalent Au–S linkages were found to be able to self-aggregate through intermolecular hydrogen bonding. Interestingly, when the hybrid GNRs (MSA-GNR) were mixed with the hydrophilic fluorescent perylene diimide (PDI) molecules and carboxylic acid modified single-wall carbon nanotubes (CNT-COOH), respectively, their aggregation behaviors were pH- and temperature-dependent, which were investigated by UV–vis, fluorescence spectra, and TEM images. The aggregates of MSA-GNR with functional PDI and CNT-COOH were able to combine the properties of each component through noncovalent interactions, providing insight into developing new multifunctional metal nanocomposites with properties tailored for their practical application.
22 Apr 2013
TL;DR: In this article, the magnetic properties of Bi-doped LaMnO3 were studied from the perspective of valence state and local distortion given by XPS and XAFS.
Abstract: The magnetic property of Bi-doped LaMnO3 was studied from perspective of valence state and local distortion given by XPS and XAFS. An isotrivalent Mn3+ is proved to be existed in samples by XPS due to trivalent Bi3+ ions doped LaMnO3. Compared to the traditional ferromagnetic-paramagnetic phase transition with double exchange interaction between mixed valence states, this phase transition in our samples with isotrivalent Mn ions is understood by superexchange interaction in the way of Mn K-edge XAFS. A net ferromagnetic moment exists when the Mn-O-Mn bond angle deviates from 180°. The regular pattern of magnetization with doping concentration is related to the disorder degree of Mn-O and Mn-Mn pairs.
30 Aug 2013
30 Aug 2013