38873-01-7Relevant articles and documents
Heteroternary cucurbit[8]uril complexes as supramolecular scaffolds for self-assembled bifunctional photoredoxcatalysts
Lutz, Fabian,Lorenzo-Parodi, Nerea,Schmidt, Torsten C.,Niemeyer, Jochen
, p. 2887 - 2890 (2021)
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.
Functionalizing the glycocalyx of living cells with supramolecular guest ligands for cucurbit[8]uril-mediated assembly
Cavatorta, Emanuela,Verheijden, Mark L.,Van Roosmalen, Wies,Voskuhl, Jens,Huskens, Jurriaan,Jonkheijm, Pascal
, p. 7146 - 7149 (2016)
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.
Redox-Responsive H-Bonding: Amplifying the Effect of Electron Transfer Using Proton-Coupled Electron Transfer
Choi, Hyejeong,Baek, Kiyeol,Toenjes, Sean T.,Gustafson, Jeffrey L.,Smith, Diane K.
, p. 17271 - 17276 (2020)
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.
Supramolecular gold nanoparticle-polymer composites formed in water with cucurbit[8]uril
Coulston, Roger J.,Jones, Samuel T.,Lee, Tung-Chun,Appel, Eric A.,Scherman, Oren A.
, p. 164 - 166 (2011)
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.
Enhanced conjugated polymer fluorescence quenching by dipyridinium-based quenchers in the presence of surfactant
Dalvi-Malhotra, Jyoti,Chen, Liaohai
, p. 3873 - 3878 (2005)
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
Aptamer-based self-assembled supramolecular vesicles for pH-responsive targeted drug delivery
Wu, Shuxian,Li, Juan,Liang, Hong,Wang, Liping,Chen, Xian,Jin, Guixiao,Xu, Xiaoping,Yang, Huang-Hao
, p. 628 - 634 (2017)
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.
Supramolecular block copolymers with cucurbit[8]uril in water
Rauwald, Urs,Scherman, Oren A.
, p. 3950 - 3953 (2008)
(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.
Photoreduction of Methyl Viologen Mediated by Tris(bipyridyl)ruthenium(II) in Inert Colloidal Suspensions
Kelly, Lisa A.,Rodgers, Michael A. J.
, p. 6386 - 6391 (1994)
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.
Novel bipyridinium ionic liquids as liquid electrochromic devices
Jordao, Noemi,Cabrita, Luis,Pina, Fernando,Branco, Luis C.
, p. 3982 - 3988 (2014)
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.
How does methylviologen cation radical supply two electrons to the formate dehydrogenase in the catalytic reduction process of CO2to formate?
Amao, Yutaka,Miyaji, Akimitsu
, p. 18595 - 18605 (2020)
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.
Electronic Structure and Electrooptical Properties of Radicals Formed upon Reduction of N-Alkyl 4,4′-Bipyridylium Salts
Minin,Zakirov,Efimov,Mel’nikov,Nodova,Shapiro,Novotortsev
, p. 815 - 821 (2018)
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.
High energy and quantum efficiency in photoinduced charge separation
Weber, John M.,Rawls, Matthew T.,MacKenzie, Valerie J.,Limoges, Bradford R.,Elliott, C. Michael
, p. 313 - 320 (2007)
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.
Enzyme-Linked Immunosorbent Assay for Paraquat and Its Application to Exposure Analysis
Emon, Jeanette Van,Hammock, Bruce,Seiber, James N.
, p. 1866 - 1873 (1986)
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.
Mediated, Thin-Layer Cell, Coulometric Determination of Monomolecular Films of Trichlorosilane Viologen Derivatives at Gold and Nonconducting Surfaces
Widrig, Cindra A.,Majda, Marcin
, p. 754 - 760 (1987)
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.
Chemical redox-induced chiroptical switching of supramolecular assemblies of viologens
Ihara, Hirotaka,Ito, Mio,Iwamoto, Tatsumi,Kuwahara, Yutaka,Mani, Tomoyasu,Ryu, Naoya,Takafuji, Makoto
, p. 2019 - 2025 (2022/02/07)
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.
