- 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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- Synthesis of tetracationic organic salt from 4,4'-bipyridine
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This report describes the synthesis of a tetracationic organic salt from 4,4'-bipyridine and 1-bromooctane using 1,3-dibromopropane as a spacer just in three simple steps. A careful monooctylation of one of the nitrogen atoms of 4,4'-bipyridine using 1-bromoocatane followed by the dimeriztion using 1,3-dibromopropane as a linker resulted a tetracationic organic salt of formula [C3H6(C8Bipyr)2]Br4. 1H and 13C NMR, and CHN elemental analysis as well as ultra high vacuum spectroscopic technique (XPS) were employed to confirm the synthesis and the purity of this compound. This compound has demonstrated molar conductivity of 4320 S cm2 mol-1 unexpected from a salt with 1:4 cation to anion ratio. It is expected that this salt would have potential applications in materials such as for low-molecular-weight gelators and the preparation of solid films for organic electronic applications.
- Abebe, Atakilt,Atlabachew, Minaleshewa
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- Photosensitized Electron-Transfer Reactions in β-Cyclodextrin Aqueous Media: Effects on Dissociation of Ground-State Complexes, Charge Separation, and H2 Evolution
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Zinc(II) meso-tetrakisporphyrin, ZnTPSPyP (2), forms a ground state complex with anthraquinone-2-sulfonate, AQS- (1).The formation of the complex results in internal static quenching of the excited S state of the sensitizer and recombination of the photoproducts in the cage structure.In the presence of β-cyclodextrin (β-CD), the complex is separated due to selective association of AQS- to the receptor cavity.This process leads to the effective decay of excited ZnTPSPyP to the T state that undergoes diffusional quenching by β-CD-bound AQS-.The electron-transfer photoproducts are stabilized against back-electron-transfer reaction and AQHS-. can be accumulated under continuous illumination in the presence of cystein as the electron donor.Photoreduction of N,N'-dioctyl-4,4'-bipyridinium, C8V2+, with Ru(bpy)32+ as the sensitizer and Na2EDTA as the donor leads to the formation of a dimer aggregate (C8V+.)2.The aggregate is inactive in H2 evolution.In the presence of β-CD, the aggregate formation is prevented due to the selective association of C8V+. monomer to the cyclodextrin cavity.High quantum yields for H2 evolution in the presence of a Pt-colloid are observed with β-CD, Φ=4E-2.Flash photolysis studies reveal that the association of C8V+. to the β-CD stabilizes the intermediate photoproducts against back-electron-transfer reactions.
- Adar, Eti,Degani, Yinon,Goren, Zafrir,Willner, Itamar
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- The antitumor activity of 4,4′-bipyridinium amphiphiles
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A series of 4,4′-bipyridinium amphiphiles were synthesized and their anticancer activities were further evaluated. MTT assay showed that the cytotoxicity first increased and then decreased with the growth of carbon chains (8-16 C) at both ends of bipyridy
- Wang, Senlin,Wu, Hongshuai,Chen, Fanghui,Zhang, Yu,Zhang, Yuchen,Sun, Baiwang
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p. 33023 - 33028
(2019/10/28)
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- Synthesis of dendrimer-type viologen and its use in Pd-mediated homocoupling of aryl halides
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Dendrimer-type viologen (V2+.D.) was prepared from mesitylene and 4.4′-bipyridyl. Electroreduction of V2+.D. gave the corresponding quinoid (V0.D.), which promoted Pd-catalyzed homocoupling of aryl bromides Ar-Br to give the corresponding biaryls Ar-Ar in moderate to good yields.
- Kuroboshi, Manabu,Kojima, Atsuki,Tanaka, Hideo
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p. 2132 - 2140
(2017/11/21)
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- Heparin triggered dose dependent multi-color emission switching in water: a convenient protocol for heparinase I estimation in real-life biological fluids
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Oligo(p-phenylenevinylene) based bis-pyridinium derivatives show ‘ratiometric’ detection of heparin in water. For the first time, we present a dose-dependent, multi-color emission switching in the presence of heparin. The reversible self-assembly of probe
- Dey, Nilanjan,Samanta, Suman K.,Bhattacharya, Santanu
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supporting information
p. 1486 - 1489
(2017/02/05)
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- Viologen as catalytic organic reductant: Electro-reductive dimerization of aryl bromides in a Pd/viologen double mediatory system
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Viologen can be used as an in situ recyclable organic reductant. Pd-catalyzed electrochemical reductive coupling of aryl bromides was performed by using a catalytic amount of viologen to afford the corresponding biaryls in good to moderate yields.
- Kuroboshi, Manabu,Shiba, Takuya,Tanaka, Hideo
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p. 3666 - 3668
(2013/07/05)
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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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- 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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- Effect of asymmetric substitution on the mesomorphic behaviour of low-melting viologen salts of bis(trifluoromethanesulfonyl)amide
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We report on the synthesis and characterisation of novel ionic liquid crystals and ionic liquids based on asymmetric viologen salts of bis(trifluoromethanesulfonyl)amide (Tf2N-). The thermotropic behaviour of the salts has been thoro
- Causin, Valerio,Saielli, Giacomo
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experimental part
p. 9153 - 9162
(2010/09/06)
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- Electroreductive generation of recyclable organic reductant from N,N′-dioctyl-4,4′-bipyridinium and Pd-catalyzed reductive coupling of aryl halides
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Electroreduction of N,N′-dioctyl-4,4′-bipyridinium bis(triflimide) [C8V2+][Tf2N-] 2 in THF gave a dark blue solution of the corresponding quinoid C8V0, which worked as an efficient organic reductant for Pd-catalyzed reductive coupling of aryl bromides to give the corresponding biphenyl derivatives in good yields. After usual workup, [C8V 2+][Tf2N-]2 was recovered and reused for generation of the organic reductant C8V0. Georg Thieme Verlag Stuttgart.
- Kuroboshi, Manabu,Kobayashi, Ryoto,Nakagawa, Takayuki,Tanaka, Hideo
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scheme or table
p. 85 - 88
(2009/06/27)
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- Application of Multielectron Charge Relays in Chemical and Photochemical Debromination Processes. The Role of Induced Disproportionation of N,N'-Dioctyl-4,4'-bipyridinium Radical Cation in Two-Phase Systems
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Photochemical and chemical reduction of N,N'-dioctyl-4,4'-bipyridinium (C8V(2+), 1) to the corresponding radical cation C8V(1+.) (2) leads to an induced disproportionation of C8V(1+). in a water-organic two-phase system.This process yields the two-electron reduction product N,N'-dioctyl-4,4'(1H,1H')-bipyridylidene (C8V, 3).The induced disproportionation reaction is a result of opposite solubility properties of the disproportionation products in the two phases.The two-electron reduction product C8V (3) mediates the debromination of 1,2- and 1,1-dibromo substrates.
- Maidan, Ruben,Goren, Zafrir,Becker, James Y.,Willner, Itamar
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p. 6217 - 6222
(2007/10/02)
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