- Synthesis and tunability of highly electron-accepting, N-benzylated "phosphaviologens"
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We report a structure-property study on phosphoryl-bridged viologen analogues with a remarkably low reduction threshold. Utilizing different benzyl groups for N-quaternization, we were able to confirm the p-benzyl substituent effect on the electronic tuna
- Stolar, Monika,Borau-Garcia, Javier,Toonen, Mark,Baumgartner, Thomas
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- The effect of boronic acid acidity on performance of viologen-based boronic acids in a two-component optical glucose-sensing system
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A two-component saccharide sensing system using the fluorescent dye, hydroxypyrene trisulfonic acid, combined with a boronic acid functional viologen as a receptor/quencher in pH 7.4 buffer solution has been further investigated. The effect of substituents on the acidity of the boronic acid was measured. The boronic acid pKa changed in the expected manner when electron donating or withdrawing groups were present. The glucose binding constants were dependent on pKa, but no simple correlation was observed for the Stern-Volmer quenching constants and the fluorescence signal modulation.
- Sharrett, Zachary,Gamsey, Soya,Fat, Jonathan,Cunningham-Bryant, Daniel,Wessling, Ritchie A.,Singaram, Bakthan
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- Photochromism of Viologen Crystals
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Some viologen crystals bearing a p-toluenesulfonate anion as a counter ion were shown to exhibit reversible photoreductions (photochromism) either in air or under vacuum, whereas in a poly(N-vinyl-2-pyrrolidone) matrix all investigated viologens indicated reversible photocolor developments.Amphoteric ions such as 1,1'-bis(3-sulfonatopropyl)-4,4'-bipyridinium also developed colors with high stabilities.
- Kamogawa, Hiroyoshi,Suzuki, Tsuyoshi
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- Electrochromic Poly(chalcogenoviologen)s as Anode Materials for High-Performance Organic Radical Lithium-Ion Batteries
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A series of electrochromic electron-accepting poly(chalcogenoviologen)s with multiple, stable, and reversible redox centers were used as anodic materials in organic radical lithium-ion batteries (ORLIBs). The introduction of heavy atoms (S, Se, and Te) into the viologen scaffold significantly improved the capacity and cycling stability of the ORLIBs. Notably, the poly(Te-BnV) anode was able to intercalate 20 Li ions and showed higher conductivity and insolubility in the electrolyte, thus contributing to a reversible capacity of 502 mAh g?1 at 100 mA g?1 when the Coulombic efficiency approached 100 %. The charged/discharged state of flexible electrochromic batteries fabricated from these anodic materials could be monitored visually owing to the unique electrochromic and redox properties of the materials. This study opens a promising avenue for the development of organic polymer-based electrodes for flexible hybrid visual electronics.
- Li, Guoping,Zhang, Bingjie,Wang, Jianwei,Zhao, Hongyang,Ma, Wenqiang,Xu, Letian,Zhang, Weidong,Zhou, Kun,Du, Yaping,He, Gang
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- Targeted synthesis of ionic liquid-polyoxometalate derived Mo-based electrodes for advanced electrochemical performance
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Rational design of advanced electrode materials with high capacity and long cycle stability is a great challenge for both lithium and sodium storage. In this work, we report a versatile strategy for the synthesis of N/P-codoped MoO2@carbon (N/P
- Chen, Guojian,Zhang, Lei,Zhang, Yadong,Liu, Ke,Long, Zhouyang,Wang, Ying
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- Improved complexation of paraquats with crown ether-based pyridyl cryptands
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The commonly used paraquat guest N,N′-dimethyl-4,4′-bipyridinium bis(hexafluorophosphate) (7) was targeted for structural alterations to improve the binding constants with crown ethers and cryptands. The association constant was improved by one order of magnitude (to Ka?=?1.00?×?106?mol?L?1) with the dibenzo-30-crown-10 pyridyl cryptand host 5 by changing the N-methyl groups to benzyl and the counterions from PF6 to TFSI, that is, 11. Moreover, through addition of a p-bromobenzyloxy moiety on the 4-position of the pyridyl ring of cryptand 18, an association constant of Ka?=?5.35?×?106?mol?L?1 was achieved with paraquat 11.
- Price, Terry L.,Slebodnick, Carla,Gibson, Harry W.
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- Substituent-Modulated Assembly Formation: An Approach to Enhancing the Photostability of Photoelectric-Sensitive Chalcogenide-Based Ion-Pair Hybrids
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A series of electronically active viologen dications (RV) with tunable substituent groups were utilized to hybridize with [Ge4S10]4- (T2 cluster) to form the hybrids of T2@RV. These hybrids exhibited variable supermolecula
- Lin, Jian,Fu, Zhixing,Zhang, Jiaxu,Zhu, Yujia,Hu, Dandan,Li, Dongsheng,Wu, Tao
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- Spectroscopic detection of excited-state electron transfer in porphyrin viologen system
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Pulsed laser excitation (354.7 nm, 10 ns pulse) of a pyridyltritolylporphyrin chromophore covalently linked to a dibenzylviologen, Bz2V2+, electron acceptor (porphyrin-viologen, P-V2+) in CH3CN leads to intramolecular electron transfer quenching of the porphyrin singlet excited state within the laser pulsewidth to reduce the linked Bz2V2+ to Bz2V+.Transient Bz2V+ can be detected directly by resonance Raman spectroscopy.The same transient features are obtained from pulsed laser excitation of a mixture of porphyrin (P) and dibenzylviologen in CH3CN where Bz2V2+ quenches the porphyrin fluorescence, establishing bimolecular excited state electron transfer quenching to yield Bz2V+.Confirmation of our assignments of the transient Bz2V+ comes from comparison of the spectra with the resonance Raman spectrum of an authentic sample of Bz2V+, and of electrochemically reduced P-V2+ which has been spectroscopically confirmed to formed P-V+.Fluorescence lifetime determinations for P-V2+ and P yield a rate constant for intramolecular electron transfer, ket = 8 x 1E7 s-1, consistent with the ability to observe electron transfer within the laser pulsewidth.
- Force, R. Ken,McMahon, Robert J.,Yu, Jie,Wrighton, Mark S.
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- Metal-free reduction of unsaturated carbonyls, quinones, and pyridinium salts with tetrahydroxydiboron/water
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A series of unsaturated carbonyls, quinones, and pyridinium salts have been effectively reduced to the corresponding saturated carbonyls, dihydroxybenzenes, and hydropyridines in moderate to high yields with tetrahydroxydiboron/water as a mild, convenient, and metal-free reduction system. Deuterium-labeling experiments have revealed this protocol to be an exclusive transfer hydrogenation process from water. This journal is
- Li, Tiejun,Peng, Henian,Tang, Wenjun,Tian, Duanshuai,Xu, Guangqing,Yang, He
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p. 4327 - 4337
(2021/05/31)
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- Single-molecule charge transport through positively charged electrostatic anchors
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The charge transport in single-molecule junctions depends critically on the chemical identity of the anchor groups that are used to connect the molecular wires to the electrodes. In this research, we report a new anchoring strategy, called the electrostat
- Chen, Hongliang,Brasiliense, Vitor,Mo, Jingshan,Zhang, Long,Jiao, Yang,Chen, Zhu,Jones, Leighton O.,He, Gen,Guo, Qing-Hui,Chen, Xiao-Yang,Song, Bo,Schatz, George C.,Stoddart, J. Fraser
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supporting information
p. 2886 - 2895
(2021/03/03)
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- The Host-Guest Properties Observed between the Viologens and Cyclopentanocucurbit[6]uril
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The interactions between cyclopentanocucurbit[6]uril (abbreviated as CyP6Q[6]) and a series of dialkyl-4,4′-bipyridinium and diaryl-4,4′-bipyridinium dicationic guest molecules, where the alkyl group is CH3(CH2)n with n = 0-6 (expressed as G1 to G7) and the aryl group is phenylene (G8) and xylene (G9), have been investigated in aqueous solution using 1H NMR spectroscopy, isothermal titration calorimetry (ITC), and electronic absorption spectroscopy. Our results show that G1 and G2 form 1: 1 host-guest inclusion complexes with CyP6Q[6], in which the bipyridinium core is partially embedded in the cavity of CyP6Q[6]. G3-G9 form 2: 1 dumbbell-type host-guest inclusion complexes, in which the substituents are encapsulated by CyP6Q[6]. At the same time, CyP6Q[6] was compared with several other cucurbit[n]urils (Q[n]s) and their derivatives, such as Q[6], Q[7], and TMeQ[6], which have been reported to interact with this type of guest molecule. In its binding mode, CyP6Q[6] shows many interesting and different properties, and this difference was mainly reflected with G1 and G2.
- Cheng, Si-Yuan,Qu, Yun-Xia,Tao, Zhu,Zhou, Kai-Zhi,Wei, Lian-Tong,Wang, Cong,Zhao, Wei-Wei,Jiang, Dao-Fa,Ma, Pei-Hua
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p. 601 - 607
(2020/01/24)
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- Heterogeneous viologen catalysts for metal-free and selective oxidations
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Metal-free oxidation, a green chemistry process, has drawn significant attention from catalysis researchers. However, most oxidation processes are completed by homogeneous metal-free catalysts, whereas heterogeneous metal-free materials have been developed with limited successes. In this study, polymerized ionic networks (PINs) with N,N′-dialkyl-4,4′-bipyridinium units as heterogeneous viologen type of catalysts exhibited high efficiency in the oxidation of aromatic sulfides/alcohols to sulfoxides/aldehydes, respectively (conversion: >90%, selectivity: >95%). The catalytic performance of PINs originates from the electron-accepting ability of the viologen unit, which can reduce H2O2 into an active species. Especially, the synthesis of PIN catalysts is a one-step simple polymerization reaction between benzyl bromide and bipyridine in air. The metal-free heterogeneous feature, high selectivity, mild conditions (60 °C, 1 h), and the facile preparation of the catalyst make the current selective oxidation approach attractive.
- Hou, Shengtai,Chen, Nanqing,Zhang, Pengfei,Dai, Sheng
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supporting information
p. 1455 - 1460
(2019/03/26)
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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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- Syntheses and characterization of two novel 1D Pb(II) Halide supramolecular polymers possessing incomplete Cubane subunit directed by π-conjugated Dication templates
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Two novel cation-templated complexes, {(1, 4-PMBP)[Pb4I10] DMF}n(1) {(DBBP)2[Pb5I8Br6]}n(2), (1, 4-PMBP 2Br =1, 1"-[1, 4-phenylene-bis(methylene)]bis-4, 4'-bipyridiniu
- Ma, Chengjie,Liu, Mei,Zhang, Wenli,Du, Haijuan,Li, Yao,Wang, Chaohai,Niu, Yunyin
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p. 1235 - 1242
(2015/10/06)
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- Pyridinium salts and ylides as partial structures of photoresponsive Merrifield resins
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Merrifield resin was treated with 4,4′-bipyridine and 2,4′-bipyridine, respectively, to give photochromic materials. On exposure to light, reversible color changes are observable. These resins also serve as indicators because reversible color changes are
- Albrecht, Marcel,Yulikov, Maxim,Kohn, Thomas,Jeschke, Gunnar,Adams, Joerg,Schmidt, Andreas
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experimental part
p. 3025 - 3034
(2011/08/03)
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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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- The effect of boronic acid-positioning in an optical glucose-sensing ensemble
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The quenching of the anionic dye 8-hydroxypyrene-1,3,6-trisulfonic acid trisodium salt (pyranine) with three different boronic acid-substituted benzyl viologens was determined, and the fluorescence signal modulation obtained upon addition of glucose to th
- Gamsey, Soya,Baxter, Nichol A.,Sharrett, Zachary,Cordes, David B.,Olmstead, Marilyn M.,Wessling, Ritchie A.,Singaram, Bakthan
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p. 6321 - 6331
(2007/10/03)
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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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- Synthesis of New Pyrazinomethylviologens and the Substituent Effect of the Nitrogen Ylid on their Absorption Spectra
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Reaction of 2-bromomethyl-5,6-dicyano-3-phenylpyrazine with 4,4'-bipyridyl gave the corresponding mono- 3a and bis-substituted viologen 4. The absorption spectra of dyes 3 and 4 measured at the cathode in an electric cell show narrow absorption bands, and produce hypsochromic shifts of 40-90 nm compared with those of the radical cation of 1,1'-dibenzyl-4,4'-bipyridinium bromide 6 which shows a broad absorption band. Dye 4 produced bathochromic shift of 70 nm from that of 6 caused by the contribution of the nitrogen ylid in 4. Their absorption spectra and electronic properties are correlated with their chemical structures.
- Jaung, Jae-yun,Fukunishi, Koushi,Kim, Sung Dong,Jeong, Sung Hoon,Kim, Sung Hoon
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p. 825 - 834
(2007/10/03)
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- Electrocatalytic Reduction of Oxygen by Viologen-Linked Polypyrrole Coated on Glassy Carbon Electrode
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Viologen linked-N-substituted pyrroles were prepared and polymerized by electrochemical oxidation on glassy carbon, giving viologen-modified electrodes.The electrons were transferred from the modified electrode to O2 through the viologen moiety.The modifi
- Kijima, Masashi,Sakawaki, Akira,Sato, Takeo
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p. 2323 - 2325
(2007/10/02)
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- Experimental Evaluation of the VBCM Model for Nucleophilic Substitutions
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The rate of the substitution reaction, kSUB, between different conjugated nucleophiles (enolates, dianions and neutral nucleophiles) and alkyl and benzyl halides has been measured by cyclic voltammetry.The SET vs.SN2 character of the transition state (TS) was evaluated from the value of kSUB relative to the outersphere electron transfer rate, kSET, obtained for the reaction between an anion radical (A*-) with the same oxidation potential as the nucleophile and the alkyl halide in question.For different alkyl and benzyl halides kSUB/kSET ratios in the range 1-4000 were obtained, which was interpreted as indicating the possibility of transition states between a pure SET TS and a pure SN2 TS rather than competition between SET and SN2.The observed changes in kSUB and kSUB/kSET as a function of the choice of nucleophile (Nu), alkyl group (R) and leaving group (X) were compared with the changes predicted by the valence bond configuration mixing model (VBCM).It was concluded that the VBCM model has reasonably good predictive power in the region of the continuous TS model which is SET-like.
- Lund, Torben,Lund, Henning
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p. 269 - 279
(2007/10/02)
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- Glow Discharge Plasma Reduction of Viologen Homologues and Organic Dyes in Solid and Solvated States
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A variety of viologen homologues (1,1'-disubstituted 4.4'-dipyridinium ions) were reduced both in solid and in DMF solution by a radio-frequency gaseous plasma.Reduction occured very rapidly and quantitatively with plasma exposure and resulted in the corresponding cation radicals.These radicals were oxidized on exposure to air but reduced again with repeated plasma exposure indicating that the reduction is an one-electron process.In a similar manner organic compounds such as methylene blue and brilliant green were also reduced effectively by the plasma.From kinetic study and ESR measurements approximate electron concentrations responsible for the reduction in the plasma were estimated.
- Osada, Yoshihito,Iriyama, Yu
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p. 5951 - 5956
(2007/10/02)
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- PHOTOCHEMICALLY INDUCED REDUCTION OF VIOLOGENS IN SOLID POLAR APROTIC POLYMER MATRICES
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Photochemically induced reversible reduction of viologens in solid polar aprotic polymer matrices proceeds much more efficiently than that in protic ones.The effects of the N-substituent and anionic part of viologens were also considerable.
- Kamogawa, Hiroyoshi,Masui, Toshiaki,Nanasawa, Masato
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p. 1145 - 1148
(2007/10/02)
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