- Heteroternary cucurbit[8]uril complexes as supramolecular scaffolds for self-assembled bifunctional photoredoxcatalysts
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The self-assembly of bifunctional photoredoxcatalysts is reported. A series of photosensitizers and water-reducing catalysts were functionalized with viologen- and naphthol-units, respectively. Subsequent formation of the heteroternary cucurbit[8]uril-viologen-naphthol complexes was used for the constitution of bifunctional photoredoxcatalysts for hydrogen generation.
- Lutz, Fabian,Lorenzo-Parodi, Nerea,Schmidt, Torsten C.,Niemeyer, Jochen
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- Construction of supramolecular multi-component assemblies by using allosteric interactions
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Supramolecular complexes between two cavity-appended porphyrin hosts and three bifunctional guests are described. The host with a single cavity exclusively forms dimers with the bifunctional guests, while the double cavity host yields tetramers and higher order assemblies. The role of allosteric interactions in the binding and assembly process is highlighted.
- Veling, Nico,Thomassen, Paul J.,Thordarson, Pall,Elemans, Johannes A.A.W.,Nolte, Roeland J.M.,Rowan, Alan E.
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- Functionalizing the glycocalyx of living cells with supramolecular guest ligands for cucurbit[8]uril-mediated assembly
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Multiple naphthol ligands were installed on the glycocalyx of white blood cells via metabolic labeling and subsequent strain promoted azide-alkyne cycloaddition. Only when cucurbit[8]uril was present to drive the formation of ternary complexes, cells specifically assembled on a methylviologen functionalized supported lipid bilayer through multivalent interactions.
- Cavatorta, Emanuela,Verheijden, Mark L.,Van Roosmalen, Wies,Voskuhl, Jens,Huskens, Jurriaan,Jonkheijm, Pascal
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- Cucurbit[8]uril induced heterodimerization of methylviologen and naphthalene functionalized proteins
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Cucurbit[8]uril is a supramolecular inducer of protein heterodimerization for proteins appended with methylviologen and naphthalene host elements. Two sets of fluorescent protein pairs, which visualize the specific protein assembly process, enabled the interplay of the supramolecular elements with the proteins to be established.
- Uhlenheuer, Dana A.,Young, Jacqui F.,Nguyen, Hoang D.,Scheepstra, Marcel,Brunsveld, Luc
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- Redox-Responsive H-Bonding: Amplifying the Effect of Electron Transfer Using Proton-Coupled Electron Transfer
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A new strategy to create highly redox-responsive H-bond dimers based on proton-coupled electron transfer is proposed that capitalizes on the importance of secondary H-bonds in determining overall binding strength in H-bond dimers. Electron transfer induced proton transfer across a H-bond can be used to significantly strengthen the overall binding by both creating strong ionic H-bonds and changing the secondary H-bonds from unfavorable to favorable. The viability and potency of this approach are demonstrated with an electroactive DAD (A = H-acceptor, D = H-donor) array, H(MQ+)H, paired with an electroinactive ADA array, O(NH)O. NMR titration of H(MQ+)H with O(NH)O in 0.1 M NBu4PF6/CD2Cl2 gives a Kassoc of 500 M-1, typical of DAD-ADA dimers. However, upon two-electron reduction in 0.1 M NBu4PF6/CH2Cl2, cyclic voltammetry studies indicate a 1.8 × 105 increase in binding strength, corresponding to a very large Kassoc of 9 × 107 M-1. The latter value is typical of DDD-AAA H-bond dimers, consistent with proton transfer across the central H-bond upon reduction.
- Choi, Hyejeong,Baek, Kiyeol,Toenjes, Sean T.,Gustafson, Jeffrey L.,Smith, Diane K.
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- N-ALKYL-4,4'-BIPYRIDYL. A NEW EFFICIENT ELECTRON CARRIER IN THE PHOTOCHEMICAL HYDROGEN PRODUCING SYSTEM
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Various pyridine derivatives were found to be effective electron carriers in the photochemical hydrogen generating system consisting of ascorbic acid as a reproducible electron donor, zinc meso-tetra (4-hydroxysulphophenyl) porphyrin as a photocatalyst, a
- Tabushi, Iwao,Yazaki, Akira
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- Supramolecular gold nanoparticle-polymer composites formed in water with cucurbit[8]uril
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A gold nanoparticle-polymer composite material has been prepared in water using cucurbit[8]uril as a supramolecular "handcuff" to hold together viologen-functionalised gold nanoparticles and a naphthol-functionalised acrylamide copolymer.
- Coulston, Roger J.,Jones, Samuel T.,Lee, Tung-Chun,Appel, Eric A.,Scherman, Oren A.
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- Improved synthesis of cationic pyridinium-substituted indolizines
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This paper describes the optimization of the synthesis of pyridinium-substituted indolizines. Different conditions, solution and solid-phase synthesis were used for the key step of [3+2] cycloaddition. The best yields and shortest reaction time were obtai
- Furdui, Bianca,Dinica, Rodica,Druta, Ioan I.,Demeunynck, Martine
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- Enhanced conjugated polymer fluorescence quenching by dipyridinium-based quenchers in the presence of surfactant
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Poly[(2-methoxy-5-propyloxysulfonate)phenylene vinylene] (MPS-PPV) was synthesized directly from its bischloromethylated monomer, considerably reducing the total number of steps involved in the polymer preparation. For the first time, a simple technique o
- Dalvi-Malhotra, Jyoti,Chen, Liaohai
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- Light driven formation of a supramolecular system with three CB[8]s locked between redox-active Ru(bpy)3 complexes
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Three CB[8]s have been reversibly locked between two Ru(bpy) 3-viologen complexes by light driven electron transfer reactions.
- Andersson, Samir,Zou, Dapeng,Zhang, Rong,Sun, Shiguo,Sun, Licheng
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- Aptamer-based self-assembled supramolecular vesicles for pH-responsive targeted drug delivery
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Supramolecular vesicles have received great attention in biomedical application due to their inherent features, including simple synthesis and tunable amphiphilicity of the building blocks. Despite tremendous research efforts, developing supramolecular vesicles with targeted recognition and controlled release remains a major challenge. Herein, we constructed a novel aptamer-based self-assembled supramolecular vesicle by host-guest complexation of pyrene, viologen lipid, and cucurbit[8]urils for pH-responsive and targeted drug delivery. The proposed supramolecular vesicles are easy to be assembled and offer simple drug loading. Based on confocal fluorescence microscopy and cytotoxicity experiments, the drug-loaded supramolecular vesicles were shown to possess highly efficient internalization and apparent cytotoxic effect on target cancer cells, but not control cells. Furthermore, through simple aptamer or drug substitution, supramolecular vesicles can be applied to a variety of target cell lines and drugs, making it widely applicable. Taking advantage of the easy preparation, good stability, rapid pH response, and cell targeting ability, the aptamer-based self-assembled supramolecular vesicles hold great promise in controlled-release biomedical applications and targeted cancer therapy.
- Wu, Shuxian,Li, Juan,Liang, Hong,Wang, Liping,Chen, Xian,Jin, Guixiao,Xu, Xiaoping,Yang, Huang-Hao
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- Discovery of unusually stable reduced viologen via synergistic folding and encapsulation
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The preparation and identification of an unusually stable viologen radical has been demonstrated. The intramolecular interactions of bis-viologen species such as 1,1”-[1,2-phenylenebis(methylene)]bis[1’-methyl-4,4’-bipyridinium] (1) and 1,1”-(1,3-propaned
- MacInnes, Molly M.,Cousineau, Benjamin R.,Youngs, Sarah M.,Sinniah, Kumar,Reczek, Joseph J.,Maldonado, Stephen
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- Supramolecular block copolymers with cucurbit[8]uril in water
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(Figure Presented) Be my guest! A supramolecular amphiphilic diblock copolymer was prepared with a cucurbit[8]uril molecular "handcuff" (see picture). It subsequently undergoes a hierarchical self-assembly process, resulting in the formation of a tertiary, compartmentalized nanostructure.
- Rauwald, Urs,Scherman, Oren A.
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- Transmembrane Electron Transfer Mediated by a Viologen: A Mechanism Involving Diffusion of Doubly Reduced Viologen Formed by Disproportionation of Viologen Radical
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A stopped-flow study of electron transfer (ET) through vesicle membranes composed of egg lecithin (phosphatidyl choline) was made.Cetylmethylviologen (N-methyl-N'-hexadecyl-4,4'-bipyridine, CMV) acted as transmembrane redox mediator by transferring electrons from dithionite in the bulk aqueous phase to CMV(2+) or ferricyanide in the vesicle interior.Transmembrane ET was observed when viologen was bound only to the outer interface and the overall reaction was second order in viologen radical on the outside (out).Both facts exclude electron tunneling/self-exchange as mechanism.A mechanism is proposed where the rate-determining step is the disproportionation of two viologen radicals initially formed at the outer interface of the vesicle (2CMV(+) = CMV(0) + CMV(2+)).CMV(0) diffuses rapidly through the membrane and is re-oxidized in the vesicle interior.A brief study of Ru(bpy)3(2+)-sensitized, photoinduced transmembrane ET was made, giving further evidence for transmembrane viologen migration.Preliminary results from pulse-radiolytically induced transmembrane ET support the observation that the reaction is second order in out.
- Hammarstroem, Leif,Almgren, Mats,Norrby, Thomas
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- Photoreduction of Methyl Viologen Mediated by Tris(bipyridyl)ruthenium(II) in Inert Colloidal Suspensions
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The photoreduction of methyl viologen, covalently attached to a tris(bipyridyl)ruthenium(II) chromophore, in suspensions of positively charged alumina-coated colloidal silica particles, via N-phenylglycine electron donor, is reported.In the tris(bipyridyl)ruthenium(II) complexes, the cenral metal atom is coordinated to two 4,4'-dicarboxy-2,2'-bipyridine ligands and thus carries a net 2- charge at pH 5.0.Coadsorption of the N-phenylglycine and ruthenium chromophore to the colloidal particles results in rapid production of reduced viologen following visible laser flash excitation of the tris (bipyridyl)ruthenium(II) complex.The yield of the radical was dependent upon the concentration of the electron donor added to the system, but its multiphasic decay was independent of both the N-phenylglycine concentration and the initial concentration of the viologen radical cation.Furthermore, both the yield and decay kinetics of the viologen radical cation were relatively independent of the number of intervening methylene units between the ruthenium complex and viologen electron acceptor.The results represent a significant improvement in charge separation yield over those previously reported for the reductive quenching of the carboxylated tris(bipyridyl)ruthenium(II) complex, absent of the covalently attached viologen, by N-phenylglycine in alumina-coated silica colloidal suspensions.
- Kelly, Lisa A.,Rodgers, Michael A. J.
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- Synthesis, Surface Activity, and Antimicrobial Efficacy of Hydrogenated Cardanol-Derived Positively Charged Asymmetric Gemini Surfactants
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Nine different hydrogenated cardanol-based quaternary ammonium compounds including one conventional single-tale single-head surfactant, one bicephalic single-tale double-head surfactant, and seven asymmetric Gemini surfactants were synthetized using a sim
- Huang, Mengen,Ma, Jingyi,Wu, Xunshen,Zhao, Min,Wang, Limin,Che, Fei,Qian, Hui
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- Novel bipyridinium ionic liquids as liquid electrochromic devices
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Novel mono and dialkylbipyridinium (viologens) cations combined with iodide, bromide, or bis(trifluoromethanesulfonyl)imide [NTf2] as anions were developed. Selective alkylation synthetic methodologies were optimized in order to obtain the desired salts in moderate to high yields and higher purities. All prepared mono- and dialkylbipyridinium salts were completely characterized by 1H, 13C, and 19F NMR spectroscopy, Fourier-transform IR spectroscopy, and elemental analysis (in the case of NTf2 salts). Melting points, glass transition temperatures by differential scanning calorimetry (DSC) studies, and decomposition temperatures were also checked for different prepared organic salts. Viscosities at specific temperatures and activation energies were determined by rheological studies (including viscosity dependence with temperature in heating and cooling processes). Electrochemical studies based on cyclic voltammetry (CV), differential pulsed voltammetry (DPV), and square-wave voltammetry (SWV) were performed in order to determine the redox potential as well as evaluate reversibility behavior of the novel bipyridinium salts. As proof of concept, we developed a reversible liquid electrochromic device in the form of a U-tube system, the most promising dialkylbipyridinium-NTf2 ionic liquid being used as the electrochromic material and the room-temperature ionic liquid (RTIL), 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)- imide [EMIM][NTf2], as a stable and efficient electrolyte. Novel mono and dialkylbipyridinium cations combined with halides and bis(trifluoromethanesulfonyl)imide anions were prepared and characterized. Thermal, rheological, and electrochemical properties were studied for different bipyridinium salts. Reversible liquid electrochromic devices composed of dialkylbipyridinium-NTf2 ionic liquids (see figure; IL=ionic liquid) have been successfully developed.
- Jordao, Noemi,Cabrita, Luis,Pina, Fernando,Branco, Luis C.
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- Hybrid Amyloid-Based Redox Hydrogel for Bioelectrocatalytic H2 Oxidation
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An artificial amyloid-based redox hydrogel was designed for mediating electron transfer between a [NiFeSe] hydrogenase and an electrode. Starting from a mutated prion-forming domain of fungal protein HET-s, a hybrid redox protein containing a single benzyl methyl viologen moiety was synthesized. This protein was able to self-assemble into structurally homogenous nanofibrils. Molecular modeling confirmed that the redox groups are aligned along the fibril axis and are tethered to its core by a long, flexible polypeptide chain that allows close encounters between the fibril-bound oxidized or reduced redox groups. Redox hydrogel films capable of immobilizing the hydrogenase under mild conditions at the surface of carbon electrodes were obtained by a simple pH jump. In this way, bioelectrodes for the electrocatalytic oxidation of H2 were fabricated that afforded catalytic current densities of up to 270 μA cm?2, with an overpotential of 0.33 V, under quiescent conditions at 45 °C.
- Duraffourg, Nicolas,Leprince, Maxime,Crouzy, Serge,Hamelin, Olivier,Usson, Yves,Signor, Luca,Cavazza, Christine,Forge, Vincent,Albertin, Luca
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- How does methylviologen cation radical supply two electrons to the formate dehydrogenase in the catalytic reduction process of CO2to formate?
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Formate dehydrogenase from Candida boidinii (EC.1.2.1.2; CbFDH) is a commercially available enzyme and can be easily handled as a catalyst for the CO2 reduction to formate in the presence of NADH, single-electron reduced methylviologen (MV+) and so on. It was found that the formate oxidation to CO2 with CbFDH was suppressed using the oxidized MV as a co-enzyme and the single-electron reduced MV (MV+) was effective for the catalytic activity of CbFDH for the CO2 reduction to formate compared with that using the natural co-enzyme of NADH [Y. Amao, Chem. Lett., 2017, 46, 780-788]. The CO2 reduction to formate catalyzed by CbFDH requires two molecules of the MV+. In order to clarify the two-electron reduction process using MV+ in the CO2 reduction to formate catalyzed with CbFDH, we attempted enzyme reaction kinetics, electrochemical and quantum chemical analyses. Kinetic parameters obtained from the enzymatic kinetic analysis metric revealed an index of affinity of MV+ for CbFDH in the CO2 reduction to formate. From the results of the electrochemical analysis, it was predicted that only one molecule of MV+ was bound to CbFDH, and the MV bound to CbFDH was to be necessarily re-reduced by the electron source outside of CbFDH to supply the second electron in the CO2 reduction to formate. From the results of docking simulation and density functional theory (DFT) calculations, it was indicated that one molecule of MV bound to the position close to CO2 in the inner part of the substrate binding pocket of CbFDH contributed to the two-electron CO2 reduction to formate.
- Amao, Yutaka,Miyaji, Akimitsu
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- Polycationic Redox-Active Cyclophanes with Integrated Electron-Rich Diboron Units
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Cationic cyclophanes are widely used in a variety of applications in supramolecular chemistry and materials science. In this work the authors systematically study the integration of electron-rich diboron units with BII atoms into polycationic cyclophanes with viologen-like electron-acceptor units. They also report a first hexacationic cage-compound in which three diboron units connect two tris(4-pyridyl)triazine acceptor units. Moreover, di- and tetracationic open-structure compounds, in which one diboron unit connects two bispyridyl groups, were synthesized and the properties compared to those of the corresponding closed structures (cyclophanes). The combination of diboron electron-donor units and bi- or oligopyridyl electron-acceptor units leads to intriguing optical and redox properties.
- Filbeck, Erik,Widera, Anna,Kaifer, Elisabeth,Himmel, Hans-J?rg
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- Electronic Structure and Electrooptical Properties of Radicals Formed upon Reduction of N-Alkyl 4,4′-Bipyridylium Salts
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N-Alkyl 4,4'-bipyridylium salts were synthesized and characterized. Cyclic voltammetry investigation showed that monosubstited 4,4'-bipyridylium salts are prone to reversible single-electron reduction. The formal redox potentials vs. a saturated silver chloride electrode were determined for different potential sweep rates. High-resolution ESR spectra of the radical cations formed upon the reduction of N-substituted 4,4'- bipyridylium salts in acid media were measured and interpreted. The substituent structure and the type of anion in the molecule have a considerable effect on the spin density distribution, current–voltage characteristics, and elctrooptical properties. The applicability of monosubstituted 4,4'-bipyridylium salts as photoelectrochromic compounds was studied.
- Minin,Zakirov,Efimov,Mel’nikov,Nodova,Shapiro,Novotortsev
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- Recognition of Viologen Derivatives in Water by N-Alkyl Ammonium Resorcinarene Chlorides
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Three water-soluble N-alkyl ammonium resorcinarene chlorides decorated with terminal hydroxyl groups at the lower rims were synthesized and characterized. The receptors were decorated at the upper rim with either terminal hydroxyl, rigid cyclohexyl, or fl
- Beyeh, Ngong Kodiah,Jo, Hyun Hwa,Kolesnichenko, Igor,Pan, Fangfang,Kalenius, Elina,Anslyn, Eric V.,Ras, Robin H. A.,Rissanen, Kari
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- High energy and quantum efficiency in photoinduced charge separation
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Supramolecular triad assemblies consisting of a central trisbipyridine ruthenium(II) chromophore (C2+) with one or more appended phenothiazine electron donors (D) and a diquat-type electron acceptor (A 2+) have been shown to form long-lived photoinduced charge separated states (CSS) with unusually and consistently high quantum efficiency. Up to now, there has been no understanding for why these large efficiencies (often close to unity) are achieved across this entire class of triads when other, seemingly similar systems are often much less efficient. In the present study, using a bimolecular system consisting of a chromophore-acceptor diad (C 2+-A2+) and an N-methylphenothiazine donor, we demonstrate that a ground-state association exists between the RuL32+ and the phenothiazine prior to photoexcitation. It is this association process that is responsible for the efficient CSS formation in the bimolecular system and, by inference, also must be an essential factor in the fully intramolecular process occurring with the D-C2+-A2+ triad analogues.
- Weber, John M.,Rawls, Matthew T.,MacKenzie, Valerie J.,Limoges, Bradford R.,Elliott, C. Michael
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- Photoinduced Electron-Transfer Processes Using Organized Redox-Functionalized Bipyridinium-Polyethylenimine-TiO2 Colloids and Particulate Assemblies
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Polyethylenimine, PEI, acts as an effective supporting polymer for the stabilization of semiconductor colloids of TiO2.Chemical modification of PEI by N-(2-carboxyethyl)-N'-methyl-4,4'-bipyridinium, MVP2+ (2), generates a redox-functionalized polymer, PEI-MVP2+, that also stabilizes TiO2 colloids.Photoreduction of bipyridinium units, which are covalently linked to the polymer backbone within the TiO2-PEI-MVP2+ assembly, proceeds effectively upon excitation of the semiconductor colloid.At pH = 8.9, photoreduction of bipyridinium units of the TiO2-PEI-MVP2+ assembly is ca. 54-fold and 13-fold faster than the reduction of N,N'-dimethyl-4,4'-bipyridinium, MV2+, or N,N'-bis(3-sulfonatopropyl)-4,4'-bipyridinium, PVS0, by TiO2-PEI, respectively.At pH = 5.1, photoreduction of PEI-MVP2+ is ca. 92-fold faster than that of MV2+ and PVS0 by TiO2-PEI, respectively.The enhanced yield of reduction of the bipyridinium relay units of the TiO2-PEI-MVP2+ assembly is attributed to the control of electron-transfer reactions at the semiconductor-solution interface.The redox polymer stabilized colloid, TiO2-PEI-MVP2+, concentrates the electron relay units at the semiconductor interface.Consequently, conduction band electrons formed upon photoexcitation of the TiO2 are effectively trapped by the redox relay units on the polymer.This electron trapping competes with the degradative "electron-hole" recombination.Time-resolved laser photolysis studies reveal that the interfacial electron transfer in the TiO2-PEI-MVP2+ assembly proceeds within the laser pulse time constant (2+, by TiO2-PEI through a diffusional mechanism is slow, ket = 750 +/- 80 s-1.The photoinduced electron-transfer process in TiO2-PEI-MVP2+ was coupled to the biocatalyzed reduction of nitrate (NO3-) to nitrite (NO2-) by electrostatic association of the enzyme nitrate reductase (E.C.1.6.6.2) with the polymer backbone.This photo-biocatalyzed electron transfer was also accomplished by applying rigid, functionalized semiconductor particles.In this photosystem, nitrate reductase is covalently linked to the redox polymer PEI-MVP2+-TiO2.
- Willner, Itamar,Eichen, Yoav,Frank, Arthur J.,Fox, Marye Anne
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- Enzyme-Linked Immunosorbent Assay for Paraquat and Its Application to Exposure Analysis
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An enzyme-linked immunosorbent assay (ELISA) was developed for the determination of paraquat in human exposure samples.Using an antibody dilution of 1/5000, concentrations of paraquat cation in the range 0.1-27 ng/mL could be measured.Limit of detection ranged from 0.1 to 1.0 ng/mL depending on the matrix analyzed.The method had good precision, with less than 5percent between-run and less than 4percent within-run variation, and was selective for paraquat showing minimal cross reactivity with ethylparaquat, diquat, and other compounds.In comparison with a gas chromatographic method, the ELISA gave higher recoveries, was less labor intensive, and was more sensitive.The ELISA was applied to paraquat in high volume glass fiber filters, personal air monitors, worker clothing patches, and hand washes collected during aerial spraying of cotton.When the same filters were analyzed by both ELISA and GC, the ELISA consistently resulted in higher values in keeping with the greater efficiency of the sample preparation steps of ELISA.
- Emon, Jeanette Van,Hammock, Bruce,Seiber, James N.
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- Complexes of carboxyl-containing polymer and monosubstituted bipyridinium salts
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Semi-empirical PM3 method for the quantum calculations of molecular electronic structure based on NDDO integral approximation is used to investigate the complex formation of monosubstituted 4,4'-bipyridinium salts BpyR (Hal) containing a halide anion interacting with the quaternary nitrogen atom and carboxylic group of the two-units construct. Significant effect of the BpyR (Hal) electronic structure is unveiled that contributes in two different structures of these salts, namely, partial charge transfer complex and ion pair structure, both having stable energy minima. We demonstrate that (i) the structure of the N-substituent modulates the energy and electronic characteristics of monosubstituted salts BpyR with chlorine and bromine anions and (ii) the coulomb interactions between quaternary N-atom, halogen anion, and the proton of carboxylic group stimulate the transformation of the charge transfer complex into the ion pair structure. Results of calculations are compared with the experimental FTIR spectra of blends of BpyR(Hal) with Eudragit copolymer.
- Merekalova,Bondarenko,Krylsky,Zakirov,Talroze
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- Mediated, Thin-Layer Cell, Coulometric Determination of Monomolecular Films of Trichlorosilane Viologen Derivatives at Gold and Nonconducting Surfaces
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A thin-layer, mediated, coulometric titration method is developed for the determination of electroactive reagents immobilized at nonconducting surfaces.The method was used to verify the monomolecular quantities of N-methyl-N-(2-(trimethoxysilyl)ethyl)benzyl-4,4'-bipyridinium dichloride and of other viologen silane derivatives immobilized at gold electrodes.The direct electroreduction gave surface coverages on average 50percent smaller than those obtained by the mediated coulometric method.The lack of complete electroactivity of the surface-bound material in customary voltammetric experiments was confirmed spectrophotometrically.This unexpected characteristic is related to the interfacial structure of the silane layers of which some fragments appear to be passivating to the direct heterogeneous electron transfer.The high density of the lateral siloxane bridging groups in such areas was postulated to be responsible for this effect.The mediated double layer charging of an electrically unconnected, conducting interface is described and illustrated by two examples.
- Widrig, Cindra A.,Majda, Marcin
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- A novel pH-responsive Fe-MOF system for enhanced cancer treatment mediated by the Fenton reaction
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Recently, the toxic hydroxyl radical (·OH) has received wide interest for inducing cell apoptosis by increasing the intracellular reactive oxygen species (ROS) levels. Herein, a cationic polymer (MV-PAH) was rationally synthesized, and a new pH-responsive nanoreactor (DOX@Fe-MOF@PEM) was modified with the prepared cationic polymer MV-PAH multilayers by layer-by-layer (LBL) technique. The polyelectrolyte multilayer (PEM) disassembled and notably enhanced drug delivery in the weak acid environment of the tumor cell. In the cytotoxicity and apoptosis experiments, DOX@Fe-MOF@PEM revealed an advanced repression of cancer. The H2O2induced by DOX and MV-PAH could be catalyzed to generate hypertoxic ·OH through intracellular iron ions based on a Fenton-like reaction, which thereby improved the anticancer effect of DOX. This realistic strategy may create a potential way to provide a combination of ROS and chemotherapy to improve the anti-cancer effect.
- Wang, Senlin,Wu, Hongshuai,Sun, Kai,Hu, Jinzhong,Chen, Fanghui,Liu, Wen,Chen, Jian,Sun, Baiwang,Hossain, Abul Monsur Showkot
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- Chemical redox-induced chiroptical switching of supramolecular assemblies of viologens
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A chiral supramolecular assembly exhibiting redox-induced changes in its chiroptical properties was prepared using viologen-modified glutamide (G-V2+) derivatives. Achiral viologen moieties in the G-V2+ assembly were chirally orientated by glutamide groups, affording a unique orange-colored solution, with a visible absorption band at around 470 nm, having electronic circular dichroism (CD) signals (molar ellipticity [θ] = 0.58 × 105 deg cm2 dmol-1: absorption dissymmetry factors (g) = 5.2 × 10-3 at 512 nm). The G-V2+ could be reduced to its cation radical (G-V+) but retains its chiral assembly. After chemical reduction, the color change from orange to blueish violet, indicating an absorption band at approximately 560 nm, and the sign change of the CD signal from positive to negative ([θ] = -0.36 × 105 deg cm2 dmol-1; g = -2.9 × 10-3 at 580 nm) were observed in water. Subsequent oxidation re-introduces the G-V2+ chiroptical behavior before reduction.
- Ihara, Hirotaka,Ito, Mio,Iwamoto, Tatsumi,Kuwahara, Yutaka,Mani, Tomoyasu,Ryu, Naoya,Takafuji, Makoto
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p. 2019 - 2025
(2022/02/07)
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- Viologen-cucurbituril host/guest chemistry - redox control of dimerizationversusinclusion
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Two calix[4]arene systems,C234+andC244+- where 2 corresponds to the number of viologen units and 3-4 corresponds to the number of carbon atoms connecting the viologen units to the macrocyclic core - have been synthesized and led to t
- Dalvand, Parastoo,Nchimi Nono, Katia,Shetty, Dinesh,Benyettou, Farah,Asfari, Zouhair,Platas-Iglesias, Carlos,Olson, Mark A.,Trabolsi, Ali,Elhabiri, Mourad
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p. 29543 - 29554
(2021/10/08)
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- Dual-Stimuli Responsive 2D Supramolecular Organic Framework for the Detection of Azoreductase Activity
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A 2D supramolecular organic framework (SOF) based on synthetic macrocycles has been constructed in water by a self-assembly strategy. Two new organic monomers of this SOF, possessing viologen and azobenzene functional groups, form a stimuli-responsive host–guest system upon cooperatively binding with cucurbit[8]uril rings. The reversible formation and dissociation of 2D SOF can be realized by the isomerization of azobenzene under ultraviolet and visible light. The light-responsive property of the SOF is highly reversible and stable for up to four cycles. Moreover, azoreductase produced by Escherichia coli can reduce the N=N double bond of azobenzene entities, resulting in fluorescence recovery of the system. As an excellent and effective fluorescent probe, the SOF can detect azoreductase activity for real-time monitoring of the growth process of Escherichia coli. The dual-stimuli responsive 2D SOF is envisioned to drive the development of responsive devices with complex functions.
- Zhang, Hao,Liang, Feng,Yang, Ying-Wei
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supporting information
p. 198 - 205
(2019/12/12)
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- Artificial co-enzyme based on carbamoyl-modified viologen derivative cation radical for formate dehydrogenase in the catalytic CO2reduction to formate
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Formate dehydrogenase (CbFDH) from Candida boidinii is a useful biocatalyst for CO2 reduction to formate in the photoredox system, and consists of a visible-light sensitizer and an electron mediator. The electron mediator, single-electron reduced 4,4′-bipyridinium salts (4,4′-BPs) represented by methylviologen act as the co-enzyme for CbFDH in the CO2 reduction to formate. Considering that the single-electron reduced 4,4′- or 2,2′-BPs activate the CbFDH-mediated CO2 reduction to formate, the architecture of the effective co-enzyme based on the chemical modification of BP is useful for the development of the catalytic reduction of CO2 to formate with CbFDH. NAD+ has a carbamoyl group or nicotinamide moiety, which can form hydrogen bonds with some amino residues in CbFDH. Thus, we predicted that the affinity of 4,4′-BP for CbFDH could be improved by introducing a carbamoyl group or nicotinamide moiety into 4,4′-BP. In this work, the interaction between the single-electron reduced 1-carbamoylmethyl-1′-methyl-4,4′-bipyridinium salt, 1,1′-dicarbamoylmethyl-4,4′-bipyridinium salt and 1-nicotinamidethyl-1′-methyl-4,4′-bipyridinium salt and CbFDH in the CO2 reduction to formate is elucidated by enzymatic kinetic analysis, the docking simulation and density functional theory calculation.
- Miyaji, Akimitsu,Amao, Yutaka
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p. 18808 - 18812
(2020/11/18)
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- PH clock instructed transient supramolecular peptide amphiphile and its vesicular assembly
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A new strategy to construct a transient supramolecular peptide amphiphile (SPA) and its vesicular aggregates is displayed. The construction of the amphiphile is assisted by the ternary complexation of cucurbit[8]uril and pH responsive imine bond formation. The transient assembly follows a pH clock set by urea/urease and hydrolysis of glucono delta-lactone (GdL). The transient assembly can be repeated for several cycles through feeding the system with the fuel (urea).
- Dowari, Payel,Das, Saurav,Pramanik, Bapan,Das, Debapratim
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supporting information
p. 14119 - 14122
(2019/12/02)
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- Preparation method of N-methyl-4, 4'-bipyridinium iodide
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The invention discloses a preparation method of N-methyl-4, 4'-bipyridylium iodide. The preparation method comprises the following steps: (1) dissolving 4, 4'-bipyridine in acetonitrile, adding alkyliodide at the room temperature, and performing reflux reaction under the protection of nitrogen; and (2) after the reaction is finished, cooling a reaction solution to the room temperature, filteringto obtain filter residues, and carrying out aftertreatment to obtain N-methyl-4, 4'-bipyridinium iodide. According to the method, 4, 4'-bipyridine and alkyl iodide are taken as basic raw materials, atarget product can be synthesized through a one-step method, tail gas and byproducts generated in a reaction process are easy to treat, and the preparation method is simple to operate, low in production cost and suitable for large-scale production.
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Paragraph 0023-0037
(2019/06/27)
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- “Precipitation on Nanoparticles”: Attractive Intermolecular Interactions Stabilize Specific Ligand Ratios on the Surfaces of Nanoparticles
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Confining organic molecules to the surfaces of inorganic nanoparticles can induce intermolecular interactions between them, which can affect the composition of the mixed self-assembled monolayers obtained by co-adsorption from solution of two different molecules. Two thiolated ligands (a dialkylviologen and a zwitterionic sulfobetaine) that can interact with each other electrostatically were coadsorbed onto gold nanoparticles. The nanoparticles favor a narrow range of ratios of these two molecules that is largely independent of the molar ratio in solution. Changing the solution molar ratio of the two ligands by a factor of 5 000 affects the on-nanoparticle ratio of these ligands by only threefold. This behavior is reminiscent of the formation of insoluble inorganic salts (such as AgCl), which similarly compensate positive and negative charges upon crystallizing. Our results pave the way towards developing well-defined hybrid organic–inorganic nanostructures.
- Chu, Zonglin,Han, Yanxiao,Král, Petr,Klajn, Rafal
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supporting information
p. 7023 - 7027
(2018/06/15)
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- The improvement of formic acid production from CO2 with visible-light energy and formate dehydrogenase by the function of the viologen derivative with carbamoylmethyl group as an electron carrier
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Formate dehydrogenase (FDH) is an attractive biocatalyst for converting CO2 to formic acid in ambient conditions. FDH is applied to the catalyst for the visible-light induced CO2 – formic acid conversion system consisting of an electron donor, a photosensitizaer and an electron carrier. For improvement of the formic acid production efficiency with this system, the enhancement of electron relay processes among a photosensitizer, an electron carrier and FDH has been needed. We aimed to solve this problem by developing novel electron carrier based on the viologen derivative instead of methylviologen (MV), widely used as an electron carreir. In this study, viologen derivatives with carbamoyl group, 1,1′-dicarbamoylmethyl-4,4′-bipyridinium diiodide (CV) and 1-carbamoylmethyl-1′-methyl-4,4′-bipyridinium diiodide (CMV) were synthesized and applied to the electron carrier for photoinduced CO2-formic acid conversion system consisting of triethanolamine, water-soluble zinc porphyrin and FDH. By using CV and CMV, the effective formic acid production in the system of water-soluble zinc porphyrin and FDH was improved compared with that of MV.
- Ikeyama, Shusaku,Katagiri, Takayuki,Amao, Yutaka
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p. 362 - 367
(2017/10/17)
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- Abnormal co-enzymatic behavior of a one-electron reduced bipyridinium salt with a carbamoyl group on the catalytic activity of CO2 reduction by formate dehydrogenase
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One-electron reduced bipyridinium salt (BP) acts as a co-enzyme for formate dehydrogenase (FDH) from Candida boidinii in CO2 reduction to formic acid. By using BP with a carbamoyl group (CMV), the CO2 reduction catalytic activity of FDH was improved compared with those of other BPs. Moreover, CMV did not act as a co-enzyme for FDH in the presence of more than 20 times higher concentration of CMV against FDH. This is the first report of BP with the abnormal co-enzymatic behavior on the catalytic activity of CO2 reduction by FDH.
- Ikeyama,Amao
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p. 15556 - 15560
(2018/10/04)
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- Designer Two-Electron Storage Viologen Anolyte Materials for Neutral Aqueous Organic Redox Flow Batteries
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Aqueous organic redox flow batteries (AORFBs) are highly attractive for large-scale energy storage because redox-active organic molecules are synthetically tunable, sustainable, and potentially low cost. Here, we show that rational molecular engineering yielded a series of two-electron storage viologen molecules as anolyte materials for AORFBs. In neutral NaCl solutions, these viologen anolytes have a theoretical capacity of up to 96.5 Ah/L in H2O and exhibit a reduction potential as low as ?0.78 V versus normal hydrogen electrode. The neutral aqueous flow batteries with two two-electron storage viologen molecules delivered a cell voltage of up to 1.38 V and outstanding battery performance, including a power density of up to 130 mW/cm2, capacity retention of up to 99.99% per cycle, and energy efficiency of up to 65% at 60 mA/cm2. Density functional theory calculations revealed that the 1e? and 2e? reduced redox states of these molecules were stabilized by the high charge delocalization of their frontier SOMO or HOMO. Renewable energy (e.g., solar and wind) can make a significant contribution to meeting the increasing global energy demands. However, its successful penetration into the existing electrical grids requires effective energy-storage solutions to overcome its intermittence. Redox flow batteries (RFBs) are a suitable option for large-scale energy-storage applications (up to MW/MWh). There is an urgent call to develop low-cost and benign RFB technologies to meet the burgeoning energy-storage demands. A new generation of aqueous organic RFBs utilizing sustainable and tunable redox-active organic molecules has emerged as a game changer for electrochemical energy storage. In the present study, we report a class of rationally designed highly reductive and high-charge capacity redox-active viologen molecules as a class of two-electron storage anolyte materials that promise aqueous organic RFBs with high voltage, high power density, and high energy density. Liu and co-workers reported a series of rationally designed two-electron storage viologen molecules as anolytes for high-voltage and high-power pH-neutral aqueous organic redox flow batteries. The synthetic and computational chemistry presented has opened a new avenue for designing energy-dense redox-active organic molecules for building neutral AORFBs with high power density and high energy density, and it promises economical, benign, and widespread uses of redox flow batteries in large-scale energy storage.
- DeBruler, Camden,Hu, Bo,Moss, Jared,Liu, Xuan,Luo, Jian,Sun, Yujie,Liu, T. Leo
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p. 961 - 978
(2017/12/26)
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- The Viologen Cation Radical Pimer: A Case of Dispersion-Driven Bonding
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The π bonds between organic radicals have generated excitement as an orthogonal interaction for designing self-assembling architectures in water. A systematic investigation of the effect of the viologen cation radical structure on the strength and nature of the pimer bond is provided. A striking and unexpected feature of this π bond is that the bond strength is unchanged by substitution with electron-donating groups or withdrawing groups or with increased conjugation. Furthermore, the interaction is undiminished by sterically bulky N-alkyl groups. Theoretical modeling indicates that strong dispersion forces dominate the interaction between the radicals, rationalizing the insensitivity of the bonding interaction to substituents: The stacking of polarizable π radicals leads to attractive dispersion forces in excess of typical dispersion interactions of small molecules and helps overcome the Coulombic repulsion of bringing two cationic species into contact.
- Geraskina, Margarita R.,Dutton, Andrew S.,Juetten, Mark J.,Wood, Samuel A.,Winter, Arthur H.
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supporting information
p. 9435 - 9439
(2017/08/01)
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- The antibacterial activity of 4,4′-bipyridinium amphiphiles with conventional, bicephalic and gemini architectures
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Dialkyl 4,4′-bipyridinium compounds are widely employed for their useful redox properties, and are commonly known as viologens due to their intense coloration upon reduction. Despite their prevalence and amphiphilic nature, the antibacterial activity of these compounds remains largely unreported. We have thus prepared a series of mono- and bis-alkylated analogs of 4,4′-bipyridine to investigate structure-activity relationships in their inhibition of a battery of Gram positive and Gram negative bacteria. The prepared cationic compounds were conventional (one cationic head, one non-polar tail), bicephalic (two heads, one tail), or gemini (two heads, two tails) in their amphiphilic structure. Additionally, an isomeric series of six bis-alkylated compounds ranging from symmetric (PQ-11,11) to highly asymmetric (PQ-20,2) were prepared. Four themes of bioactivity emerged: (1) the most bioactive compounds were gemini in structure; (2) 22 carbons in the alkyl chains, with little to modest asymmetry, led to optimal activity; (3) bicephalic compounds were generally comparable to conventional amphiphiles, though only about 12 carbons in the alkyl chains were solubilized in water by each cationic nitrogen; (4) the effects of counterion identity were not evident between chlorides and bromides; however, the presence of the iodide counterion inhibited dissolution in all compounds tested. Three isomeric compounds with little to no asymmetry in tail length, PQ-11,11, PQ-12,10, and PQ-14,8, prepared as the bromide salts, showed comparable and highly potent activity, with MIC levels around 2 μM against 3 of 4 bacteria tested. The simple (one- to two-step) syntheses of potent antimicrobials portend well for future optimization.
- Grenier, Melissa C.,Davis, Robert W.,Wilson-Henjum, Kelsey L.,Ladow, Jade E.,Black, Jacob W.,Caran, Kevin L.,Seifert, Kyle,Minbiole, Kevin P.C.
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supporting information; experimental part
p. 4055 - 4058
(2012/07/13)
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- A new signal-on photoelectrochemical biosensor based on a graphene/quantum-dot nanocomposite amplified by the dual-quenched effect of bipyridinium relay and AuNPs
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A new photoelectrochemical (PEC) biosensor was developed by using carboxyl-functionalized graphene and CdSe nanoparticles. This sensitive interface was then successfully applied to detection of thrombin based on the dual-quenched effect of PEC nanoparticle, which relied on the electron transfer of a bipyridinium relay and energy transfer of AuNPs. After recognition with an aptamer, the PEC nanoparticle was removed and a signal-on PEC biosensor was obtained. Moreover, the bio-barcode technique used in the preparation of PEC nanoparticle could avoid cross-reaction and enhances the sensitivity. Taking advantages of the various methods mentioned above, the sensitivity could be easily enhanced. In addition, in this work we also investigated graphene that was modified with different functional groups and AuNPs of different particle sizes. Under optimal conditions, a detection limit of 5.9×10-15 M was achieved. With its simplicity, selectivity, and sensitivity, this strategy shows great promise for the fabrication of highly efficient PEC biosensors. PECking order! A new photoelectrochemical (PEC) biosensor was developed by using carboxyl-functionalized graphene and CdSe nanoparticles (NPs). This sensitive interface was successfully applied to detection of thrombin based on the dual-quenched effect of a PEC nanoparticle, which relied on the electron transfer of a bipyridinium relay and energy transfer of AuNPs (see figure). After recognition with an aptamer, the PEC nanoparticle was removed and a signal-on PEC biosensor was obtained. (TEOA=triethanolamine.).
- Zhang, Xiaoru,Xu, Yunpeng,Yang, Yanqiang,Jin, Xia,Ye, Sujuan,Zhang, Shusheng,Jiang, Lilin
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supporting information
p. 16411 - 16418
(2013/02/22)
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- Photophysical and electrochemical properties of platinum(ii) complexes bearing a chromophore-acceptor dyad and their photocatalytic hydrogen evolution
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A series of platinum(ii) complexes bearing a chromophore-acceptor dyad obtained by reacting 4-(p-bromomethylphenyl)-6-phenyl-2,2′-bipyridine or 4′-(p-bromomethylphenyl)-2,2′:6′,2′′-terpyridine with pyridine, 4-phenylpyridine, 4,4′-bipyridine, 1-methyl-4-(
- Zhang, Gui-Ju,Gan, Xin,Xu, Quan-Qing,Chen, Yong,Zhao, Xi-Juan,Qin, Biao,Lv, Xiao-Jun,Lai, Siu-Wai,Fu, Wen-Fu,Che, Chi-Ming
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experimental part
p. 8421 - 8429
(2012/07/30)
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- Site-selective immobilization of colloids on au substrates via a noncovalent supramolecular "handcuff"
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We have examined hierarchical supramolecular structure in the formation of colloidal arrays by immobilizing monodispersed naphthalene-functionalized colloids onto Au substrates bearing viologen moieties using the macrocyclic host molecule cucurbit[8]uril as a supramolecular "handcuff". Naphthalene-functionalized poly(methyl methacrylate)- and polystyrene-based colloids were synthesized by soap-free emulsion polymerization and characterized by dynamic light scattering and scanning electron microscopy to realize the colloidal arrays and to facilitate direct macroscopic imaging. The formation of host-stabilized ternary complexes on the surface of naphthalene-functionalized microspheres in colloidal suspension was verified by titration of a preformed viologen?CB[8] complex and followed by zeta potential measurements. Patterned self-assembled monolayers of a viologen derivative on Au substrates were formed by backfilling viologen-modified thiols after spontaneous chemisorption of "protective" alkylthiols by microcontact printing. After the initial complexation of CB[8] onto the viologen derivative on the Au substrates, monolayers of colloids with both 1D and 2D patterns could be formed and characterized by contact angle measurement, optical microscopy, and scanning electron microscopy. Control experiments indicated that no colloids were attached to the Au substrate after moderate washing by water if (1) CB[8] was replaced by a smaller analogue of the macrocyclic host, CB[6] or CB[7], (2) colloids without naphthalene-functionalities on the periphery were employed, or (3) alkanethiol was used entirely instead of viologenthiol to protect the Au substrate. These results suggest that the supramolecular ternary complexes were key to successfully bind the colloids onto the Au substrates with the CB[8] acts as a supramolecular "handcuff". The fundamental expertise gained from the study of these materials is believed to facilitate progress in the field of smart materials and wet nanotechnology and lead to the preparation of controlled reversible architectures on surfaces.
- Tian, Feng,Cheng, Nan,Nouvel, Nicolas,Geng, Jin,Scherman, Oren A.
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experimental part
p. 5323 - 5328
(2010/11/17)
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- Microwave-assisted synthesis of symmetric and asymmetric viologens
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Viologens are generally synthesized by N-alkylating 4,4′-bipyridine with alkyl halides. Under conventional heating conditions, however, their synthesis suffers from long reaction times and, often, low yields. In this work, symmetric and asymmetric viologe
- Lamberto, Massimiliano,Rastede, Elizabeth E.,Decker, Justyne,Raymo, Franisco M.
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scheme or table
p. 5618 - 5620
(2010/10/21)
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- Cyclodextrin-driven movement of cucurbit[7]uril
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(Figure Presented) The movement of cucurbit[7]uril (CB[7]) driven by α-cyclodextrin (α-CD) is investigated by various experimental techniques including NMR, ESI-MS, UV-vis, and ITC. CB[7] can form stable pseudorotaxanes with N-methyl-N′-octyl-4,4′-bipyridiniurn (MVO 2+) and N,N′-dioctyl-4,4′-bipyridinium (OV2+) dication in aqueous solution. CB[7] shuttles between the octyl and bipyridinium moieties in MVO2+, but docks at one of the octyl moieties in OV 2+. The addition of α-CD pushes CB[7] from the octyl moiety of MVO2+ or OV2+ to the bipyridinium moiety. Thermodynamically, the movement of CB[7] is mainly driven by exothermic enthalpy changes coming from the complexation of the octyl moiety of MVO2+ or OV2+ with α-CD.
- Liu, Yu,Li, Xiao-Yun,Zhang, Heng-Yi,Li, Chun-Ju,Ding, Fei
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p. 3640 - 3645
(2008/02/05)
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- Room-temperature thermotropic ionic liquid crystals: Viologen bis(triflimide) salts
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Several dicationic salts with bis(triflimide) as counterions - otherwise known as viologens - were prepared by metathesis reaction of the corresponding viologen dibromides (diiodides) with lithium triflimide in a polar solvent. They were characterized for
- Bhowmik, Pradip K.,Han, Haesook,Nedeltchev, Ivan K.,Cebe, James J.
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- Highly stable pseudo[2]rotaxanes co-driven by crown ether-ammonium and donor-acceptor interactions
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Bis-p-phenylene-34-crown-10 derivatives 1 and 2, bearing one and two dibenzo[24]crown-8 units, respectively, and 4,4′-dipyridinium derivatives of 3·3PF6 and of 4·4PF6, bearing one and two ammonium groups, respectively, have been synt
- Feng, Dai-Jun,Li, Xiao-Qiang,Wang, Xiao-Zhong,Jiang, Xi-Kui,Li, Zhan-Ting
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p. 6137 - 6144
(2007/10/03)
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- A convenient synthesis of [11C]paraquat and other [N-methyl-11C]bisquaternary ammonium compounds
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[11C]Paraquat was synthesized by the reaction of [11C]methyl triflate with the mono-triflate salt of 1-methyl-[4,4′]bipyridinyl. The product was selectively separated from the precursor by a microcolumn of Chelex 100 ion exchange resin. The method was applied to the synthesis of a variety of [N-methyl-11C]bisquaternary ammonium compounds. This is the first reported use of a chelating cation exchange resin for the selective purification of organic dications. Copyright
- Jewett, Douglas M.,Kilbourn, Michael R.
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p. 281 - 289
(2007/10/03)
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- Long-lived charge-separation by retarding reverse flow of charge-balancing cation and zeolite-encapsulated Ru(bpy)32+ as photosensitized electron pump from zeolite framework to externally placed viologen
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K+-exchanged, Ru(bpy)32+-encapsulating zeolite-Y [K+-Ru(bpy)32+Y] and N-[3-(dicyclohexyl-methyl)oxypropyl-N'-methyl-4,4′-bipyridinium [DCH-MV2+] were prepared, and visible light-
- Park, Yong Soo,Lee, Eun Jung,Chun, Yu Sung,Yoon, Young Deok,Yoon, Kyung Byung
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p. 7123 - 7135
(2007/10/03)
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- From bipyridines to tobacco alkaloids and related compounds
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Starting from structural considerations which led to the hypothesis that a chemical relationship could exist between two families of natural compounds (mainly pyridinic and pyrrolidinic alkaloids), experiments were carried out in order to establish a correlation route between the two studied classes. Of special interest was the central position of nicotine in these studies, and the main part of this work was devoted to the synthesis of nicotine starting from bipyridines. It was thus necessary to determine the conditions for selective reactions on one aromatic ring of bipyridines (N-methylation, N-oxidation and reduction of the heterocycle). Ring contraction procedure allowed us to obtain nicotine from the parent compound (3,3′-bipyridine). Complementary studies yielded various isomers of piperidinylpyridines (hexahydro derivatives of bipyridines) in a regiochemically controlled manner by means of original methods. Elsevier,.
- Plaquevent, Jean-Christophe,Chichaoui, Ilhame
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p. 369 - 379
(2007/10/03)
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