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Synthesis and Characterization of Photoresponsive Macromolecule for Biomedical Application
摘要： Azobenzene, a photo switcher, has attracted increasing interest due to its structural response to photo stimulus in the field of information science and chemical sensing in the recent decades. However, limited water solubility and cytotoxicity restrained their applications in the biomedical field. In research, HA-AZO has been designed as a water soluble photo switcher in biomedical application. Synthesized HA-AZO had good water-solubility and a stable π-π? transition absorbance peak trans-isomer. With exposure to UV, transformation from trans-isomer to cis-isomer of HA-AZO could be realized according to UV spectra. Reversely, trans-isomer could be gradually recovered from cis-isomer in the dark. Simultaneously, quick response and slow recovery could be detected in the process of structural change. Moreover, repeated illumination was further used to detect the antifatigue property of HA-AZO, which showed no sign of fatigue during 20 circles. The influence of pH value on UV spectrum for HA-AZO was investigated in the work. Importantly, in acid solution, HA-AZO no longer showed any photoresponsive property. Additionally, the status of HA-AZO under the effect of UV light was investigated by DLS results and TEM image. Finally, in vitro cytotoxicity evaluations were performed to show the effects of photoresponsive macromolecule on cells.
关键词： photoresponsive macromolecule,photo switcher,biomedical application,hyaluronic acid,azobenzene
更新于2025-09-10 09:29:36
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Emissive Azobenzenes Delivered on a Silver Coordination Polymer
摘要： Azobenzene has become a ubiquitous component of functional molecules and polymeric materials because of the light-induced trans → cis isomerization of the diazene group. In contrast, there are very few applications utilizing azobenzene luminescence, since the excitation energy typically dissipates via nonradiative pathways. Inspired by our earlier studies with 2,2′-bis[N,N′-(2-pyridyl)methyl]diaminoazobenzene (AzoAMoP) and related compounds, we investigated a series of five aminoazobenzene derivatives and their corresponding silver complexes. Four of the aminoazobenzene ligands, which exhibit no emission under ambient conditions, form silver coordination polymers that are luminescent at room temperature. AzoAEpP (2,2′-bis[N,N′-(4-pyridyl)ethyl]diaminoazobenzene) assembles into a three-dimensional coordination polymer (AgAAEpP) that undergoes a reversible loss of emission upon the addition of metal-coordinating analytes such as pyridine. The switching behavior is consistent with the disassembly and reassembly of the coordination polymer driven by displacement of the aminoazobenzene ligands by coordinating analytes.
关键词： Reversible emission switching,Aminoazobenzene derivatives,Silver coordination polymers,Luminescence,Azobenzene
更新于2025-09-10 09:29:36
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Manipulating azobenzene photoisomerization through strong light–molecule coupling
摘要： The formation of hybrid light–molecule states (polaritons) offers a new strategy to manipulate the photochemistry of molecules. To fully exploit its potential, one needs to build a toolbox of polaritonic phenomenologies that supplement those of standard photochemistry. By means of a state-of-the-art computational photochemistry approach extended to the strong-coupling regime, here we disclose various mechanisms peculiar of polaritonic chemistry: coherent population oscillations between polaritons, quenching by trapping in dead-end polaritonic states and the alteration of the photochemical reaction pathway and quantum yields. We focus on azobenzene photoisomerization, that encompasses the essential features of complex photochemical reactions such as the presence of conical intersections and reaction coordinates involving multiple internal modes. In the strong coupling regime, a polaritonic conical intersection arises and we characterize its role in the photochemical process. Our chemically detailed simulations provide a framework to rationalize how the strong coupling impacts the photochemistry of realistic molecules.
关键词： azobenzene,photochemistry,polaritons,photoisomerization,strong coupling
更新于2025-09-10 09:29:36
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Ortho-substituted azobenzene: shedding light on new benefits
摘要： Novel functional polymeric microcapsules, based on modified azobenzene moieties, are exhaustively investigated, both from a theoretical and experimental points of view. Theoretical calculations and several measurements demonstrate that visible light can act as a trigger for release of encapsulated material, as a consequence of trans-cis isomerization which modifies microcapsule surface topography and can induce a “squeezing” release mechanism. Interfacial polymerization of an oil-in-water emulsion is performed and leads to core-shell microcapsules which are characterized by means of atomic force microscopy (AFM), optical microscopy (OM), scanning electron microscopy (SEM) and light scattering. These analyses put into evidence that microcapsules’ size and surface morphology are strongly affected by irradiation under visible light: moreover, these changes can be reverted by sample exposure to temperatures around 50?°C. This last evidence is also confirmed by NMR kinetic analyses on modified azobenzene moiety. Finally, it is shown that these smart microcapsules can be successfully used to get a controlled release of actives such as fragrancies, as a consequence of visible light irradiation, as confirmed by an olfactive panel.
关键词： microcapsules,interfacial polymerization,ortho-substituted azobenzene,Chemistry for Beauty and Health 2018
更新于2025-09-10 09:29:36
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Direct Imaging of Photo-Switching Molecular Conformations Using Individual Metal Atom Markers
摘要： Photo-switching behavior of individual organic molecules was imaged by annular dark-field scanning transmission electron microscopy (ADF-STEM) using a highly electron beam transparent graphene support. Photo-switching azobenzene derivatives with ligands at each ends containing single transition metal atoms (Pt) were designed (Pt-complex), and the distance between the strong ADF-STEM contrast from the two Pt atoms in each Pt-complex is used to track molecular length changes. UV irradiation was used to induce photo-switching of the Pt complex on graphene, and we show that the measured Pt-Pt distances within isolated molecules decreases from ~2.1 nm to ~1.4 nm, indicative of a trans-to-cis isomerization. Light illumination of the Pt-complex on the graphene support also caused their diffusion out from initial clusters to the surrounding area of graphene, indicating that the light-activated mobilization overcomes the inter-molecular van der Waals interactions. This approach shows how individual isolated heavy metal atoms can be included as markers into complex molecules to track their structural changes using ADF-STEM on graphene supports, providing an effective method to study a diverse range of complex organic materials at the single molecule level.
关键词： annular dark-field scanning transmission electron microscopy,photo-switch,direct imaging,graphene support,heavy atom marker,azobenzene
更新于2025-09-09 09:28:46
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A light-responsive RNA aptamer for an azobenzene derivative
摘要： Regulation of complex biological networks has proven to be a key bottleneck in synthetic biology. Interactions between the structurally flexible RNA and various other molecules in the form of riboswitches have shown a high-regulation specificity and efficiency and synthetic riboswitches have filled the toolbox of devices in many synthetic biology applications. Here we report the development of a novel, small molecule binding RNA aptamer, whose binding is dependent on light-induced change of conformation of its small molecule ligand. As ligand we chose an azobenzene because of its reliable photoswitchability and modified it with chloramphenicol for a better interaction with RNA. The synthesis of the ligand ‘azoCm’ was followed by extensive biophysical analysis regarding its stability and photoswitchability. RNA aptamers were identified after several cycles of in vitro selection and then studied regarding their binding specificity and affinity toward the ligand. We show the successful development of an RNA aptamer that selectively binds to only the trans photoisomer of azoCm with a KD of 545 nM. As the aptamer cannot bind to the irradiated ligand (λ = 365 nm), a light-selective RNA binding system is provided. Further studies may now result in the engineering of a reliable, light-responsible riboswitch.
关键词： synthetic biology,photoswitchability,riboswitch,azobenzene,RNA aptamer
更新于2025-09-09 09:28:46
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Visual colorimetric and fluorescence turn-on probe for Cu(II) ion based on coordination and catalyzed oxidative cyclization of ortho amino azobenzene
摘要： 2,2′-diaminoazobenzene (L1), a visual colorimetric and fluorescence turn-on detection probe for Cu2+ ion, has been discovered successfully. The yellow L1 solution changed into light-purple solution rapidly with dropping of Cu2+ ion observed by the naked eyes, for the formation of 1:1 complex of L1 and Cu2+ ion calculated by Job-plot method. Non-emissive L1 transformed into 2-(2-aminophenyl) benzotriazole (L1-BTA) with strong fluorescence at the peak around 475 nm, owing to the Cu2+ catalyzed oxidative cyclization of L1, accompanied by the fluorescence intensity gradually increasing within 20 min. And L1 was applied for quantitative detection of Cu2+ with good linear relationship between its UV absorbance and Cu2+ concentration, and exhibited high fluorescence selectivity toward Cu2+ over other metal ions (Fe3+, Zn2+, Cd2+, Co2+, Ni2+, Mn2+, Na+, Al3+ and Ca2+) in EtOH solution.
关键词： Cu(II) ion,Oxidative cyclization,Fluorescence probe,Coordination,Amino azobenzene
更新于2025-09-04 15:30:14
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Synthesis and investigation of charge transport properties in adducts of hole transporting carbazole derivatives and push-pull azobenzenes
摘要： In order to investigate the viability of a material design for bulk heterojunction (BHJ) organic solar cells, where hole transporting group is bound to the donor moiety, we report the synthesis and charge transport characteristics of 3-(diphenylamino)carbazolyl- functionalized derivatives of 2-(4-((4-(dimethylamino)phenyl)diazenyl)benzylidene)-1H-indene-1,3-dione (DMAAzi) chromophore. Three different bounding configurations were examined in these adducts. Additionally, a trityl- functionalized derivative of DMAAzi was prepared and used for comparison purposes. All of the synthesized materials form thin amorphous films from volatile organic solvents and exhibit glass transition temperatures in the range from 89 °C to 124 °C. The molecular ionization energy and electron affinity energy levels in thin films were measured. Photo-induced time of flight (ToF) method was used in to determine charge carrier drift mobilities. It was found out that the formation of deep charge trap states with local energies at approximately 0.60 - 0.78 eV takes place and has a considerable negative effect on the hole drift mobility of the investigated compounds.
关键词： charge transport,molecular glasses,carbazole,organic photovoltaics,azobenzene dyes
更新于2025-09-04 15:30:14
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A photoresponsive molecularly imprinted polymer with rapid visible-light-induced photoswitching for 4-ethylphenol in red wine
摘要： The trans to cis isomerization of the azobenzene chromophore in most azobenzene-based photoresponsive molecularly imprinted polymers (MIPs) is initiated by UV irradiation. This limits the application of these materials in cases where UV light toxicity is an issue, such as in biological systems, food monitoring, and drug delivery. Herein we report a tetra-ortho-methyl substituted azobenzene, (4-[(4-methacryloyloxy)-2,6-dimethyl phenylazo]-3,5-dimethyl benzenesulfonic acid (MADPADSA). The photoswitching of MADPADSA could be induced by visible-light in 4-hydroxyethylpiperazineethanesulfonic acid (HEPES) buffer-ethanol (4:1, v/v) at pH 7.0, however, the photo-isomerization was slow. With the use of MADPADSA as a functional monomer, NaYF4:Yb3+,Er3+ as a substrate, 4-ethylphenol (4-EP) as a template, a novel photoresponsive surface molecularly imprinted polymer NaYF4:Yb3+,Er3+@MIP was obtained. The NaYF4:Yb3+,Er3+@MIP displayed rapid visible-light-induced photoswitching. The NaYF4:Yb3+,Er3+ substrate could efficiently increase the trans to cis isomerization rate of the photoresponsive MIP on its surface, which was faster than that of the corresponding azobenzene monomer MADPADSA. Possible reasons for this effect were investigated by fluorescence spectroscopy. NaYF4:Yb3+,Er3+@MIP displayed good specificity toward 4-EP with a specific binding constant (Kd) of 3.67 × 10?6 mol L?1 and an apparent maximum adsorption capacity (Qmax) of 10.73 μmol g?1, respectively. NaYF4:Yb3+,Er3+@MIP was applied to determine the concentration of 4-EP in red wine with good efficiency and a limit of detection lower than the value that could cause an unpleasant off-flavor.
关键词： Molecularly imprinted polymer,Visible-light-induced photoswitching,4-Ethylphenol,Red wine,Azobenzene
更新于2025-09-04 15:30:14
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Ultrasonic Studies of Solid Azobenzene-Decorated Polymer Thin Films
摘要： This work investigates the effect of ultrasound on switching of cis azobenzene isomers to their trans counterparts in solid films of methyl methacrylate and methacryloyloxyazobenzene copolymers [P(MMA/MOAB)]. Ultraviolet?visible and 1H nuclear magnetic resonance spectroscopies demonstrate that 46% of the cis isomer converts to the trans form purely by ultrasonic agitation and 46% converts to the trans isomer by localized ultrasound-induced heating effects. Comparative studies of isomerization by ultrasound wave, heat, and visible irradiation show that ultrasound exposure requires a longer time to switch the cis-to-trans conformation. The estimated activation energy for the cis-to-trans conversion in solid polymer films is shown to be comparable to previous values of azobenzene isomerization, indicating that incorporation of the chromophore in a polymeric system affects the kinetics of transition but not the barriers to conformational change.
关键词： azobenzene,nuclear magnetic resonance spectroscopy,polymer thin films,ultrasound,isomerization,ultraviolet?visible spectroscopy
更新于2025-09-04 15:30:14