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Spiropyran

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https://www.readbyqxmd.com/read/27889853/photo-physical-behavior-and-fluorescence-of-thermo-switchable-nanocomposite-based-on-methyl-methacrylate-spirobenzopyran
#1
Shohre Rouhani, Malihe Pishvaei
Nanocomposites with thermo and photo-switchable fluorescent properties were synthesized via mini-emulsion polymerization based on spiropyran and methyl methacrylate monomer. The photophysical behavior of fluorescence nanocomposites was investigated by fluorescence spectrophotometry in different temperature, UV-light and time of exposure. It was found that methyl methacrylate polymer is capable of acting as a protective layer and play a critical role in improving the photostability of colorants. The nanocomposites exhibited excellent fluorescent thermo-switching action with respect to the free spiro molecule...
November 26, 2016: Journal of Fluorescence
https://www.readbyqxmd.com/read/27830865/controlling-the-lifetimes-of-dynamic-nanoparticle-aggregates-by-spiropyran-functionalization
#2
Pintu K Kundu, Sanjib Das, Johannes Ahrens, Rafal Klajn
Novel light-responsive nanoparticles were synthesized by decorating the surfaces of gold and silver nanoparticles with a nitrospiropyran molecular photoswitch. Upon exposure to UV light in nonpolar solvents, these nanoparticles self-assembled to afford spherical aggregates, which disassembled rapidly when the UV stimulus was turned off. The sizes of these aggregates depended on the nanoparticle concentration, and their lifetimes could be controlled by adjusting the surface concentration of nitrospiropyran on the nanoparticles...
November 10, 2016: Nanoscale
https://www.readbyqxmd.com/read/27819106/accidental-degeneracy-in-the-spiropyran-radical-cation-charge-transfer-between-two-orthogonal-rings-inducing-ultra-efficient-reactivity
#3
David Mendive-Tapia, Luuk Kortekaas, Jorn D Steen, Aurélie Perrier, Benjamin Lasorne, Wesley R Browne, Denis Jacquemin
Photochromism of the spiropyran radical cation to the corresponding merocyanine form is investigated by a combination of electrochemical oxidation, UV/vis absorption spectroscopy, spectroelectrochemistry and first-principles calculations (TD-DFT, CAS-SCF and CAS-PT2). First, we demonstrate that the ring-opening of mono-spiropyrans occurs upon one-electron oxidation and that it can be driven photochemically as well as thermally, with trapping of the merocyanine by protonation. Second, in order to explain this experimentally observed spectroelectrochemical behaviour we suggest a theoretical mechanism based on the reactivity of the two lowest electronic excited-states, which promotes effective electron transfer from the indoline (nitrogen-ring) to the pyran (oxygen-ring) moieties (and vice versa) through a conical intersection seam of degeneracy...
November 16, 2016: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/27791322/temperature-controlled-switchable-photochromism-in-solid-materials
#4
Alex Julià-López, Jordi Hernando, Daniel Ruiz-Molina, Pablo González-Monje, Josep Sedó, Claudio Roscini
A novel strategy to achieve thermally switchable photochromism in solid materials is reported, which relies on the preparation of polymeric core-shell capsules containing solutions of photochromic dyes in acidic phase-change materials. Upon changing the phase (solid or liquid) of the encapsulated medium, one of the two photochromic states of the system is selectively stabilized on demand, allowing for reversible interconversion between direct and reverse photochromism when thermally scanning through the melting temperature of the phase-change material...
October 28, 2016: Angewandte Chemie
https://www.readbyqxmd.com/read/27711358/a-dual-functional-supramolecular-hydrogel-based-on-a-spiropyran-galactose-conjugate-for-target-mediated-and-light-controlled-delivery-of-microrna-into-cells
#5
Xiao Xiao, Jing Hu, Xingxing Wang, Lei Huang, Yingjie Chen, Wei Wang, Jinbo Li, Yan Zhang
A supramolecular hydrogel formed by spiropyran conjugated galactose was developed for light-controlled release of miR-122 and target-mediated delivery of the miRNA into HepG2 cells cultured on top of the gel.
October 13, 2016: Chemical Communications: Chem Comm
https://www.readbyqxmd.com/read/27649065/tunable-morphology-of-spiropyran-assemblies-from-nanospheres-to-nanorods
#6
Zhen Wu, Kai Pan, Baozhong Lü, Le Ma, Wantai Yang, Meizhen Yin
Spiropyran (SP), which can respond to acid, ultraviolet irradiation, and mechanical force, has received great attention as a classic molecule for the construction of stimuli-responsive materials. However, the self-assembly behavior of SP with a tunable morphology has rarely been investigated. In the present work, a SP derivative bearing two carboxyl groups and one hydroxyl group was prepared and used as a model to investigate the optical properties, molecular self-assembly, and morphology of SP. This pH-responsive derivative could undergo a large morphology variation from a sphere- to a rodlike structure by adjusting the acidity...
November 7, 2016: Chemistry, An Asian Journal
https://www.readbyqxmd.com/read/27616191/a-high-contrast-tri-state-fluorescent-switch-properties-and-applications
#7
Xing Su, Yi Wang, Xiaofeng Fang, Yu-Mo Zhang, Ting Zhang, Minjie Li, Yifei Liu, Tingting Lin, Sean Xiao-An Zhang
A high contrast tri-state fluorescent switch (FSPTPE) with both emission color change and on/off switching is achieved in a single molecular system by fusing the aggregation-induced emissive tetraphenylethene (TPE) with a molecular switch of spiropyran (SP). In contrast to most of the reported solid-state fluorescent switches, FSPTPE only exists in the amorphous phase in the ring-closed form owing to its highly asymmetric molecular geometry and weak intermolecular interactions, which leads to its grinding-inert stable cyan emission in the solid state...
September 12, 2016: Chemistry, An Asian Journal
https://www.readbyqxmd.com/read/27602432/mixed-monolayers-of-spiropyrans-maximize-tunneling-conductance-switching-by-photoisomerization-at-the-molecule-electrode-interface-in-egain-junctions
#8
Sumit Kumar, Jochem T van Herpt, Régis Y N Gengler, Ben L Feringa, Petra Rudolf, Ryan C Chiechi
This paper describes the photoinduced switching of conductance in tunneling junctions comprising self-assembled monolayers of a spiropyran moiety using eutectic Ga-In top contacts. Despite separation of the spiropyran unit from the electrode by a long alkyl ester chain, we observe an increase in the current density J of a factor of 35 at 1 V when the closed form is irradiated with UV light to induce the ring-opening reaction, one of the highest switching ratios reported for junctions incorporating self-assembled monolayers...
September 28, 2016: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/27595499/highly-axial-magnetic-anisotropy-in-a-n3-o5-dysprosium-iii-coordination-environment-generated-by-a-merocyanine-ligand
#9
Pramila Selvanathan, Gang Huang, Thierry Guizouarn, Thierry Roisnel, Guglielmo Fernandez-Garcia, Federico Totti, Boris Le Guennic, Guillaume Calvez, Kévin Bernot, Lucie Norel, Stéphane Rigaut
A spiropyran-based switchable ligand isomerizes upon reaction with lanthanide(III) precursors to generate complexes with an unusual N3 O5 coordination sphere. The air-stable dysprosium(III) complex shows a hysteresis loop at 2 K and a very strong axial magnetic anisotropy generated by the merocyanine phenolate donor.
October 17, 2016: Chemistry: a European Journal
https://www.readbyqxmd.com/read/27529635/comparative-evaluation-of-substituent-effect-on-the-photochromic-properties-of-spiropyrans-and-spirooxazines
#10
Edward I Balmond, Brandon K Tautges, Andrea L Faulkner, Victor W Or, Blanka M Hodur, Jared T Shaw, Angelique Y Louie
Spiropyrans and spirooxazines represent an important class of photochromic compounds with a wide variety of applications. In order to effectively utilize and design these photoswitches it is desirable to understand how the substituents affect photochromic properties, and how the different structural motifs compare under identical conditions. In this work a small library of photoswitches was synthesized in order to comparatively evaluate the effect of substituent modifications and structure on photochromism...
October 7, 2016: Journal of Organic Chemistry
https://www.readbyqxmd.com/read/27516153/probing-metal-ion-complexation-of-ligands-with-multiple-metal-binding-sites-the-case-of-spiropyrans
#11
Michele Baldrighi, Giulia Locatelli, John Desper, Christer B Aakeröy, Silvia Giordani
Among known molecular switches, spiropyrans attract considerable interest because of their reversible responsiveness to external stimuli and the deep conformational and electronic changes that characterize the switching process between the two isomeric forms [spiropyran (SP) and merocyanine (MC)]. Metal coordination is one of the most interesting aspects of spiropyrans for its potential in sensing, catalysis, and medicinal chemistry, but little is known about the details surrounding spiropyran-metal ion binding...
September 19, 2016: Chemistry: a European Journal
https://www.readbyqxmd.com/read/27492608/synthesis-and-spectroscopic-investigation-of-diketopyrrolopyrrole-spiropyran-dyad-for-fluorescent-switch-application
#12
Siva Doddi, K Narayanaswamy, Bheerappagari Ramakrishna, Surya Prakash Singh, Prakriti Ranjan Bangal
We report the synthesis and characterization of a new fluorescent dyad SP-DPP-SP(9) via efficient palladium-catalyzed Sonogashira coupling of prop-2-yn-1-yl 3-(3',3'dimethyl-6-nitrospiro[chromene-2,2'-indolin]-1'-yl)propanoatespiropyran, SP(8), a well known photochromic accepter, with 3,6-bis(5-bromothiophen-2-yl)-2,5-bis((R)-2-ethylhexyl)-2,5-dihydropyrrolo[3,4-c]pyrrole-1,4-dione, DPP(4), a highly fluorescent donor. Under visible light exposure the SP unit is in a closed hydrophobic form, whereas under UV irradiation it converts to a polar, hydrophilic open form named Merocyanine (MC), which is responsible for functioning of photo-switch application...
November 2016: Journal of Fluorescence
https://www.readbyqxmd.com/read/27456166/photoswitchable-spiropyran-dyads-for-biological-imaging
#13
Yaoyao Xiong, Pablo Rivera-Fuentes, Erdinc Sezgin, Andreas Vargas Jentzsch, Christian Eggeling, Harry L Anderson
The synthesis of a small-molecule dyad consisting of a far-red-emitting silicon rhodamine dye that is covalently linked to a photochromic spironaphthothiopyran unit, which serves as a photoswitchable quencher, is reported. This system can be switched reversibly between the fluorescent and nonfluorescent states using visible light at wavelengths of 405 and 630 nm, respectively, and it works effectively in aqueous solution. Live-cell imaging demonstrates that this dyad has several desirable features, including excellent membrane permeability, fast and reversible modulation of fluorescence by visible light, and good contrast between the bright and dark states...
August 5, 2016: Organic Letters
https://www.readbyqxmd.com/read/27404486/light-and-solvent-controlled-self-assembly-behavior-of-spiropyran-polyoxometalate-alkyl-hybrid-molecules
#14
Yang Chu, Ali Saad, Panchao Yin, Jiayingzi Wu, Olivier Oms, Anne Dolbecq, Pierre Mialane, Tianbo Liu
A molecular photochromic spiropyran-polyoxometalate-alkyl organic-inorganic hybrid has been synthesized and fully characterized. The reversible switching of the hydrophobic spiropyran fragment to the hydrophilic merocyanine one can be easily achieved under light irradiation at different wavelengths. This switch changes the amphiphilic feature of the hybrid, leading to a light-controlled self-assembly behavior in solution. It has been shown that the hybrid can reversibly self-assemble into vesicles in polar solvents and irreversibly into reverse vesicles in non-polar solvents...
August 8, 2016: Chemistry: a European Journal
https://www.readbyqxmd.com/read/27346489/a-spiropyran-based-fluorescent-probe-for-the-specific-detection-of-%C3%AE-amyloid-peptide-oligomers-in-alzheimer-s-disease
#15
Guanglei Lv, Anyang Sun, Peng Wei, Ning Zhang, Haichuang Lan, Tao Yi
We report a new spiropyran-based fluorescent probe that exhibits high affinity and specificity towards Aβ oligomers both in vitro and in vivo. This probe can penetrate the blood brain barrier and specifically target Aβ oligomers in the brains of transgenic mice in models for Alzheimer's disease.
July 7, 2016: Chemical Communications: Chem Comm
https://www.readbyqxmd.com/read/27312622/stimuli-responsive-cellulose-modified-by-epoxy-functionalized-polymer-nanoparticles-with-photochromic-and-solvatochromic-properties
#16
Amin Abdollahi, Jaber Keyvan Rad, Ali Reza Mahdavian
Photoresponsive papers are among the fast and simple tools for detection of polarity by solvatochromic and photochromic behaviors upon UV irradiation. Here, a new, green and facile modification strategy was employed to prepare novel stimuli-responsive cellulose materials containing spiropyran by mixing microcrystalline cellulose (MCC), as a model compound, with epoxy-functionalized photochromic latex. FTIR analysis, thermal and thermo-mechanical properties were used to confirm the microstructral properties...
October 5, 2016: Carbohydrate Polymers
https://www.readbyqxmd.com/read/27268123/coumarin-spiropyran-dyad-with-a-hydrogenated-pyran-moiety-for-rapid-selective-and-sensitive-fluorometric-detection-of-cyanide-anion
#17
Yasuhiro Shiraishi, Masaya Nakamura, Naoto Hayashi, Takayuki Hirai
We synthesized a coumarin-spiropyran dyad with a hydrogenated pyran moiety (2), behaving as an off-on type fluorescent receptor for rapid, selective, and sensitive detection of cyanide anion (CN(-)) in aqueous media. The receptor itself shows almost no fluorescence with a quantum yield < 0.01, due to the delocalization of π-electrons over the molecule. Selective nucleophilic addition of CN(-) to the spirocarbon of the molecule rapidly promotes spirocycle opening within only 3 min. This leads to localization of π-electrons on the coumarin moiety and exhibits strong light-blue fluorescence at 459 nm with very high quantum yield (0...
July 5, 2016: Analytical Chemistry
https://www.readbyqxmd.com/read/27243550/fabrication-of-chemically-tunable-hierarchically-branched-polymeric-nanostructures-by-multi-branched-anodic-aluminum-oxide-templates
#18
Hanju Jo, Niko Haberkorn, Jia-Ahn Pan, Mohammad Vakili, Kornelius Nielsch, Patrick Theato
In this paper, a template-assisted replication method is demonstrated for the fabrication of hierarchically branched polymeric nanostructures composed of post-modifiable poly(pentafluorophenyl acrylate). Anodic aluminum oxide templates with various shapes of hierarchically branched pores are fabricated by an asymmetric two-step anodization process. The hierarchical polymeric nanostructures are obtained by infiltration of pentafluorophenyl acrylate with a cross-linker and photoinitiator, followed by polymerization and selective removal of the template...
June 28, 2016: Langmuir: the ACS Journal of Surfaces and Colloids
https://www.readbyqxmd.com/read/27227655/diastereoselective-synthesis-of-structurally-and-stereochemically-diversified-2-oxa-7-azabicyclo-4-1-0-hept-3-enyl-carboxylates-and-their-potential-application-toward-the-synthesis-of-functionalized-pyranooxazolone-and-pyrrole-derivatives-through-skeletal-transformations
#19
Prasun Mukherjee, Asish R Das
An advanced protocol for the diastereoselective intramolecular aziridination reaction has been developed to synthesize 2-oxa-7-azabicyclo[4.1.0]hept-3-en-1-yl carboxylates from their corresponding 4-H-pyrans and spiropyrans analogues employing iodosylbenznene as the exclusive oxidant in the presence of carboxylic acid and triethylamine. High structural and stereochemical diversity of these pyran fused NH-azridine scaffolds makes them useful in evaluating their biological and pharmacological activities by SAR studies...
July 1, 2016: Journal of Organic Chemistry
https://www.readbyqxmd.com/read/27222922/photoreponsive-hybrid-nanoparticles-with-inherent-fret-activity
#20
Demetra S Achilleos, T Alan Hatton, Maria Vamvakaki
The photoactivated inherent fluorescence resonance energy transfer (FRET) properties of a hard-and-soft hybrid nanosystem comprising poly(1'-(2-methacryloxyethyl)-3',3'-dimethyl-6-nitrospiro-(2H-1-benzopyran-2,2'-indoline))-co-poly[2-(dimethylamino)ethyl methacrylate] (PSPMA-co-PDMAEMA) random copolymer brushes on silica nanoparticles are described. This unique FRET process is switched on by the simultaneous generation of isomer X and merocyanine (MC), which are bipolar in nature and comprise donor-acceptor dyads, from a single spiropyran (SP) chromophore upon UV irradiation...
June 14, 2016: Langmuir: the ACS Journal of Surfaces and Colloids
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