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Endowing Light-Inert Aqueous Surfactant Two-Phase System with Photo Responsiveness by Introducing a Trojan Horse
摘要： The ability to modulate the phase behavior of aqueous surfactant two-phase (ASTP) system reversibly with light is of great importance in both fundamental and applied science. Thus far, most of the light-responsive ASTP systems are based on covalent-modification of the component molecules. In this article, we for the first time achieve photo-responsiveness in a light-inert ASTP system by physically introducing a photo-trigger with the aid of an Trojan Horse. The ATPS system formed with sodium laurate (SL) and dodecyl tributyl amomium (DBAB) doesn’t show light responsiveness by physically mixing a light responsive azobenzene compound, 2-(4-(phenyldiazenyl)phenoxy)actate sodium (Azo). However, in the presence of the host-guest complex SL@β-CD formed with β-CD and sodium laurate (SL), the ASTP turns quickly into a homogenous suspension under visible light, which recovers to the original ASTP state again under 365 nm UV irradiation. Because the SL@β-CD complex exists harmonically with the ASTP, it can be viewed as a “Trojan horse” that becomes fatal only when the encapsulated SL is triggered to release. In the presence of the Trojan horse, the photo-responsiveness of the ASTP can be manipulated reversibly by alternatively exerting UV and visible light. Using this strategy, we are able to collect trace amount of oily components from water. The current strategy points out that it is possible to achieve light-responsiveness in light-inert systems with physical method, which may have profound impact both on the fundamental and applied science.
关键词： Cyclodextrin,Azobenzene,Trojan horse,Host-Guest Interaction,Aqueous surfactant two-phase system,Photo-Responsive
更新于2025-11-25 10:30:42
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Modulating Protein-Protein Interactions with Visible-Light Responsive Peptide Backbone Photoswitches
摘要： Life relies on a myriad of carefully orchestrated processes, in which proteins and their direct interplay ultimately determine cellular function and disease. Modulation of these complex cross-talks has recently attracted attention, even as a novel therapeutic strategy. Here, we describe the synthesis and characterization of two visible-light responsive peptide backbone photoswitches based on azobenzene derivatives to exert optical control over protein-protein interactions (PPI). Our novel peptidomimetics undergo fast isomerization and reversibility with low photochemical fatigue under alternatively blue/green-light irradiation cycles. Both bind in the nanomolar rage to the protein of interest. Importantly, our best peptidomimetic displays a clear difference between isomers in its protein-binding capacity and, in turn, in its potential to inhibit enzymatic activity via PPI disruption. In addition, crystal structure determination, docking and MD calculations give a molecular interpretation and open new avenues in the design and synthesis of future photoswitchable PPI modulators.
关键词： protein-protein interactions,photopharmacology,visible-light irradiation,azobenzene,photoswitches
更新于2025-11-21 11:20:42
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Optically switchable bistable guest–host displays in chiral-azobenzene- and dichroic-dye-doped cholesteric liquid crystals
摘要： Optically switchable bistable guest–host displays in chiral-azobenzene- and dichroic-dye-doped cholesteric liquid crystals (CA-DD-CLCs) are demonstrated. The CA-DD-CLCs in a LC cell treated by homeotropic alignment are initially in stable unwound textures. Given that all LC molecules in unwound textures are oriented perpendicularly to the substrates, the light absorbed by the doped DDs reaches the minimum value, which is considered the transparent state of the proposed CA-DD-CLCs. The CA-DD-CLCs are switched to fingerprint (FP) textures by illumination with ultraviolet (UV) light and can be switched back to unwound textures by illumination with green light. The optical switching between unwound and FP textures is based on the photo-tunable chirality of the doped CA via photoisomerization effect. The light absorbed by the doped DDs in FP textures reaches the maximum value, which is considered the dark state of the CA-DD-CLCs. Moreover, the performances of light absorption from the doped DDs when the CA-DD-CLCs are in unwound and FP textures is independent of the polarization of the incident light. Pattern information can be optically addressed (erased) in CA-DD-CLC cells by illumination with UV (green) light through a suitable photomask. The CA-DD-CLCs can be stabilized in FP textures for several tens of minutes in the dark environment. As such, the power is consumed only for the illumination of specific lights during the switching of CA-DD-CLCs between unwound and FP textures. Moreover, a transparent active matrix organic light-emitting diode (LED) display that is superimposed on top of a CA-DD-CLC cell embedded with a transparent light-guide film with suitable LED light sources for optical switching between unwound and FP textures, is proposed for augmented reality applications.
关键词： Cholesterics,Absorption,Guest-host display,Liquid crystals,Chiral azobenzene,Dichroic dyes
更新于2025-09-23 15:23:52
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Photoresponsive Circular Supramolecular Polymers: Topological Trap and Photoinduced Ring-opening Elongation
摘要： Topological features of one-dimensional macromolecular chains govern the properties and functionality of natural and synthetic polymers. To address this issue in supramolecular polymers, we have synthesized two topologically distinct supramolecular polymers with intrinsic curvature, i.e., circular and helically folded nanofibers, from azobenzene-functionalized supramolecular rosettes. When a mixture of circular and helically folded nanofibers was exposed to UV light, a selective unfolding of the latter open-ended supramolecular polymers was observed as a result of the curvature-impairing internal force produced by the trans-to-cis photoisomerization of the azobenzene. This distinct sensitivity suggests that the topological features of supramolecular polymers define their mechanical stability. Furthermore, the exposure of circular supramolecular polymers in more polar media to UV irradiation resulted in a ring-opening followed by a chain elongation, demonstrating that the circular supramolecular polymer can work as a topological kinetic trap.
关键词： topology,ring opening,azobenzene,supramolecular polymer,photoisomerization
更新于2025-09-23 15:23:52
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Metal-Organic Frameworks as Hosts for Fluorinated Azobenzenes: A Path Towards Quantitative Photoswitching with Visible Light
摘要： Fifteen new photochromic hybrid materials were synthesized by gas phase loading of fluorinated azobenzenes, namely ortho-tetrafluoroazobenzene (tF-AZB), 4H,4H'-octafluoroazobenzene (oF-AZB), and perfluoroazobenzene (pF-AZB), into the pores of the well-known metal-organic frameworks MOF-5, MIL-53(Al), MIL-53(Ga), MIL-68(Ga), and MIL-68(In). Their composition was analysed by elemental (CHNS) and DSC/TGA analysis. For pF-AZB0.34@MIL-53(Al) a structural model based on high-resolution synchrotron powder diffraction data was developed and the host-guest and guest-guest interactions were elucidated from this model. These interactions of O-H…F and π…π type were confirmed by significant shifts of the O-H frequencies in loaded and unloaded MOFs of the MIL-53 and MIL-68 series. Most remarkably, all of the synthesized F-AZB@MOF systems can be switched with visible light and some of them show almost quantitative (> 95 %) photo-isomerization between its E and Z forms with no significant fatigue after repeated switching cycles.
关键词： azobenzene,fluorinated derivatives,solid state switching,metal-organic frameworks,photochromism
更新于2025-09-23 15:23:52
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High-density Azobenzene Side Chain Polymer Brush for Azimuthal and Zenithal Orientation Photoswitching of Nematic Liquid Crystal
摘要： The azimuthal and zenithal orientation switching of nematic liquid crystals (NLCs) can be performed by photoresponsive azobenzene alignment layers called command surfaces. Such photoresponsive layers have been prepared by molecular assembly methods or spincast of polymer materials. This work reports on the photo-switching orientation behavior of NLC on a high-density brush of an azobenzene-containing side chain liquid crystalline polymer. On the high-density polymer brush surface, the zenithal homeotropic/planar photoalignment switching modes triggered by UV/visible light irradiation are reversed from those observed for traditional command surface systems, reflecting the azobenzene side chain orientation directing parallel with the substrate surface. Because the thermally stable trans-azobenzene provides the in-plane orientation of NLC, irradiation with linearly polarized visible light readily switches the azimuthal direction to an arbitrary direction, and the resulting orientation is retained persistently. This paper discusses the features of the architecture of high-density polymer brush as the command surface for NLC orientation.
关键词： azobenzene,photoalignment,photoresponsive surface,nematic liquid crystal,polymer brush
更新于2025-09-23 15:23:52
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Unique Substitution Effect at 5,5′ Positions of a Fused Azobenzene-Boron Complex with N=N Double-Bond π-Conjugated System
摘要： The recent report illustrates superior optical properties, such as near infrared emission, from the polymers with the connection positions at 4,4′ positions in the fused azobenzene–boron complex (BAz). In this study, we initially demonstrate that further narrower band gap can be realized by the substituent effect with bromine groups at 5,5′ positions of BAz than that at 4,4′ positions. From the series of mechanistic studies, perturbation of the energy levels were rationally explained by the contribution difference between the inductive effect and the variable resonance effect which is correlated to the degree of electron distribution of molecular orbitals at the substituent positions. Moreover, it was found that unique electronic states, such as delocalized highest occupied molecular orbital and localized lowest unoccupied molecular orbital, should appear on the main chains of the BAz-containing copolymers with fluorene and bithiophene units according to the optical and electrochemical data and theoretical calculations. Taking advantage of property tunability and the dramatic low LUMO energy level (near ?4.0 eV) of the BAz unit, it can be said that BAz should be a conjugated building block favorable for building advanced optoelectronic devices.
关键词： azobenzene,boron,narrow band gap,conjugated polymer,low LUMO
更新于2025-09-23 15:23:52
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Photo-isomerization of azobenzene containing surfactants induced by near-infrared light using upconversion nanoparticles (UCNPs) as mediator
摘要： Here we report on photo-isomerization of azobenzene containing surfactants induced during irradiation with near-infrared (NIR) light in the presence of upconversion nanoparticles (UCNPs) acting as mediator. The surfactant molecule consists of charged head group and hydrophobic tail with azobenzene group incorporated in alkyl chain. The azobenzene group can be reversible photo-isomerized between two states: trans- and cis- by irradiation with light of appropriate wavelength. The trans-cis photo-isomerization is induced by UV light, while cis-trans isomerization proceeds either thermally in dark, or can be accelerated by exposing to illumination with longer wavelength typically in blue/green range. We present the application of lanthanide doped upconversion nanoparticles (UCNPs) to successfully switch azobenzene containing surfactants from cis to trans conformation in bulk solution using NIR light. Using Tm3+ or Er3+ as activator ions, the UCNPs provide emission in the spectral range of 450 nm < λem < 480 nm (for Tm3+, three and four photon induced emission) or 525 nm < λem < 545 nm (for Er3+, two photon induced emission), respectively. Especially for UCNPs containing Tm3+ a good overlap of the emission with the absorption bands of the azobenzene is present. Under illumination of the surfactant solution with NIR light (λex= 976 nm) in the presence of the Tm3+-doped UCNPs, the relaxation time of cis-trans photo-isomerization was increased by almost 13-times compared to thermal relaxation. The influence of thermal heating due to the irradiation using NIR light was shown to be minor for solvents not absorbing in NIR spectral range (e.g., CHCl3) in contrast to water, which shows a distinct absorption in the NIR.
关键词： azobenzene containing surfactants,kinetic of cis-trans isomerization,up-conversion particles
更新于2025-09-23 15:23:52
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A Light-activated Polymer Composite Enables On-demand Photocontrol of Biomimetic Swimming Towards Transportation at Liquid/Air Interface
摘要： Swimmers at liquid/air interface have drawn enormous attention for their potential applications while conventional devices face problems such as dependence on fuel, difficulty in motion control and accompanying high temperature. Herein, we show one novel light-driven swimmer based on bimorph composite structure of photoresponsive liquid-crystalline polymer network and commercially available polyimide (Kapton) whose motion is highly controllable with photoirradiation. The bilayer-structured film shows quickly photoinduced bending towards the Kapton side on exposure to UV light and recovers immediately after removal of light. When placed on liquid surface, the swimmer propels itself continually though rhythmic beating the liquid like a dolphin moving forward with its tail fin. Besides, light-powered rotation of the swimmer is successfully achieved by simply changing the length-width ratio and the irradiation site, mimicking the function of a dolphin’s pectoral fin. Combining the together, on-demand forward movement and rotation motion directional control of the photo-driven swimmer can be readily obtained at room temperature, showing promising for miniaturized transportation.
关键词： bionic motion,azobenzene,miniaturized transportation,light-driven device,photomechanical oscillation
更新于2025-09-23 15:22:29
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Light-powered, artificial molecular pumps: a minimalistic approach
摘要： The realization of artificial molecular motors capable of converting energy into mechanical work is a fascinating challenge of nanotechnology and requires reactive systems that can operate away from chemical equilibrium. This article describes the design and construction of a simple, supramolecular ensemble in which light irradiation causes the directional transit of a macrocycle along a nonsymmetric molecular axle, thus forming the basis for the development of artificial molecular pumps.
关键词： molecular machine,azobenzene,rotaxane,supramolecular chemistry,photochemistry
更新于2025-09-23 15:22:29