- Ultra-fast rotors for molecular machines and functional materials via halogen bonding: Crystals of 1,4-bis(iodoethynyl)bicyclo[2.2.2]octane with distinct gigahertz rotation at two sites
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As a point of entry to investigate the potential of halogen-bonding interactions in the construction of functional materials and crystalline molecular machines, samples of 1,4-bis(iodoethynyl)bicyclo[2.2.2]octane (BIBCO) were synthesized and crystallized. Knowing that halogen-bonding interactions are common between electron-rich acetylenic carbons and electron-deficient iodines, it was expected that the BIBCO rotors would be an ideal platform to investigate the formation of a crystalline array of molecular rotors. Variable temperature single crystal X-ray crystallography established the presence of a halogen-bonded network, characterized by lamellarly ordered layers of crystallographically unique BIBCO rotors, which undergo a reversible monoclinic-to-triclinic phase transition at 110 K. In order to elucidate the rotational frequencies and the activation parameters of the BIBCO molecular rotors, variable-temperature 1H wide-line and 13C cross-polarization/magic-angle spinning solid-state NMR experiments were performed at temperatures between 27 and 290 K. Analysis of the 1H spin-lattice relaxation and second moment as a function of temperature revealed two dynamic processes simultaneously present over the entire temperature range studied, with temperature-dependent rotational rates of krot = 5.21 × 1010 s-1·exp(-1.48 kcal·mol -1/RT) and krot= 8.00 × 1010 s -1·exp(-2.75 kcal·mol-1/RT). Impressively, these correspond to room temperature rotational rates of 4.3 and 0.8 GHz, respectively. Notably, the high-temperature plastic crystalline phase I of bicyclo[2.2.2]octane has a reported activation energy of 1.84 kcal·mol-1 for rotation about the 1,4 axis, which is 24% larger than Ea = 1.48 kcal·mol-1 for the same rotational motion of the fastest BIBCO rotor; yet, the BIBCO rotor has three fewer degrees of translational freedom and two fewer degrees of rotational freedom! Even more so, these rates represent some of the fastest engineered molecular machines, to date. The results of this study highlight the potential of halogen bonding as a valuable construction tool for the design and the synthesis of amphidynamic artificial molecular machines and suggest the potential of modulating properties that depend on the dielectric behavior of crystalline media.
- Lemouchi, Cyprien,Vogelsberg, Cortnie S.,Zorina, Leokadiya,Simonov, Sergey,Batail, Patrick,Brown, Stuart,Garcia-Garibay, Miguel A.
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- Discovery of novel 2,5-dihydroxyterephthalamide derivatives as multifunctional agents for the treatment of Alzheimer's disease
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A series of 2,5-dihydroxyterephthalamide derivatives were designed, synthesized and evaluated as multifunctional agents for the treatment of Alzheimer's disease. In vitro assays demonstrated that most of the derivatives exhibited good multifunctional activities. Among them, compound 9d showed the best inhibitory activity against both RatAChE and EeAChE (IC50 = 0.56 μM and 5.12 μM, respectively). Moreover, 9d exhibited excellent inhibitory effects on self-induced Aβ1–42 aggregation (IC50 = 3.05 μM) and Cu2+-induced Aβ1–42 aggregation (71.7% at 25.0 μM), and displayed significant disaggregation ability to self- and Cu2+-induced Aβ1–42 aggregation fibrils (75.2% and 77.2% at 25.0 μM, respectively). Furthermore, 9d also showed biometal chelating abilities, antioxidant activity, anti-neuroinflammatory activities and appropriate BBB permeability. These multifunctional properties highlight 9d as promising candidate for further studies directed to the development of novel drugs against AD.
- Song, Qing,Li, Yan,Cao, Zhongcheng,Liu, Hongyan,Tian, Chaoquan,Yang, Ziyi,Qiang, Xiaoming,Tan, Zhenghuai,Deng, Yong
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p. 6115 - 6127
(2018/11/23)
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- Synthesis of 4 - carboxymethyl cyclohexane carboxylic acid of the new method (by machine translation)
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The invention relates to a method for the synthesis of the compounds. Synthesis of 4 - carboxymethyl cyclohexane carboxylic acid of the new method, 1st step succinyl ding acid diethyl ester synthesis: to sodium hydride, tertiary butyl alcohol and succinic acid diethyl ester as the raw material to make the succinyl ding acid diethyl ester; 2nd step synthesis of intermediate I: to sodium hydride, succinyl ding succinic acid ester and 1, 2 - Dibromoethane as raw materials get intermediate I; 3rd step products 1 and 2 synthesis: in the reaction kettle to join the intermediate I, potassium hydroxide, ethanol and water, reflux reaction to obtain the intermediate I of the potassium salt; take another in the reactor after the adding of the potassium salt, potassium hydroxide, hydrazine hydrate, ethylene glycol, heating reflux reaction, to obtain the solid 4 - carboxymethyl cyclohexane carboxylic acid product 1, most of the mother liquor in the product 2. The invention synthetic route is reasonable in design, brief, gathers warm reaction conditions, easy operation, low cost and easy availability of raw materials, the products made good selectivity, easy product separation, has the advantages of high yield and purity. (by machine translation)
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Paragraph 0005; 0019-0021
(2017/10/07)
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- An efficient five-component synthesis of thioether containing dihydropyrano[2,3-c]pyrazoles: a green domino strategy
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An efficient route for the synthesis of novel thioether containing dihydropyrano[2,3-c]pyrazoles has been accomplished via a solvent-free, catalyst-free, one-pot, five component domino strategy. This synthetic approach offers several advantages such as an easy work-up, no need for purification techniques and a short reaction time with good atom economy and high yields of the products (81-86%).
- Ramesh, Vediyappan,Shanmugam, Sivakumar,Devi, Natarajan Savitha
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p. 9993 - 10001
(2016/12/07)
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- Synthesis of Substituted 3(2H)-Furanones Using Alkylative Intramolecular Cyclization of Sulfonium Salts
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The facile alkylative intramolecular cyclization of 3-alkoxycarbonyl-2-oxopropyldiphenylsulfonium salts is described. This simple method can be readily applied to the synthesis of a novel family of 4-alkylated 3(2H)-furanones in moderate to high yields under mild conditions via a one-pot process.
- Inagaki, Sho,Ukaku, Mika,Chiba, Akira,Takahashi, Fumi,Yoshimi, Yasuharu,Morita, Toshio,Kawano, Tomikazu
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p. 8363 - 8369
(2016/09/28)
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- Synthesis and antimicrobial activities of a series of 2,5-substituent 1,4-cyclohexanedione derivatives
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A series of 2,5-substituent 1,4-cyclohexanedione derivatives compounds were designed and synthesized. Their structures were identified by elemental analysis, 1H NMR, IR spectra. Their assayed antibacterial (Escherichia coli, Bacillus subtilis) and antifungal (Candida albicans) activities were also evaluated by MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide) method. The results of biological test showed 2,5-dibenzylformate 1,4-cyclohexanedione (11) and 2,5-diformanilide 1,4-cyclohexanedione (12) have favorable antimicrobial activity with MICs of 26.7, 33.6, 24.2 and 32.3 μg/mL against Escherichia coli and Bacillus subtilis, respectively. Copyright
- Liu, Hui-Lian,Wang, Qing-Zhong,Guo, Shu-Hua
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p. 1349 - 1352
(2013/05/09)
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- Direct amination of γ-Halo-β-ketoesters with anilines
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The direct amination of α-haloacetoacetates with anilines is described. Compared to existing methods, this simple protocol provides an attractive strategy to prepare diverse γ-anilino-β-ketoesters in one step. Good to excellent yields of the amination products were obtained under robust conditions, providing versatile and useful scaffolds.
- Zhang, Yinan,Silverman, Richard B.
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scheme or table
p. 3462 - 3467
(2012/05/20)
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- New ultrahigh affinity host-guest complexes of cucurbit[7]uril with bicyclo[2.2.2]octane and adamantane guests: Thermodynamic analysis and evaluation of M2 affinity calculations
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A dicationic ferrocene derivative has previously been shown to bind cucurbit[7]uril (CB[7]) in water with ultrahigh affinity (ΔGo= -21 kcal/mol). Here, we describe new compounds that bind aqueous CB[7] equally well, validating our prior suggestion that they, too, would be ultrahigh affinity CB[7] guests. The present guests, which are based upon either a bicyclo[2.2.2]octane or adamantane core, have no metal atoms, so these results also confirm that the remarkably high affinities of the ferrocene-based guest need not be attributed to metal-specific interactions. Because we used the M2 method to compute the affinities of several of the new host-guest systems prior to synthesizing them, the present results also provide for the first blinded evaluation of this computational method. The blinded calculations agree reasonably well with experiment and successfully reproduce the observation that the new adamantane-based guests achieve extremely high affinities, despite the fact that they position a cationic substituent at only one electronegative portal of the CB[7] host. However, there are also significant deviations from experiment, and these lead to the correction of a procedural error and an instructive evaluation of the sensitivity of the calculations to physically reasonable variations in molecular energy parameters. The new experimental and computational results presented here bear on the physical mechanisms of molecular recognition, the accuracy of the M2 method, and the usefulness of host-guest systems as test-beds for computational methods.
- Moghaddam, Sarvin,Yang, Cheng,Rekharsky, Mikhail,Ko, Young Ho,Kim, Kimoon,Inoue, Yoshihisa,Gilson, Michael K.
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supporting information; scheme or table
p. 3570 - 3581
(2011/05/04)
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- Hydrogen-bonded deugdan heterocomplex: Structure and stability and a scalable synthesis of DeUG with reactive functionality
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A convenient, scalable synthesis of the supramolecular building block 7-deazaguanine-based urea (DeUG) is reported. Incorporation of reactive moieties (DeUG azide 10 and alkyne 11 for copper-catalyzed azide-alkyne cycloadditions, "click chemistry") and a demonstration of transesterification (DeUG glycol, 12) highlights the versatility. X-ray structures of DeUG and a DeUG-DAN heterocomplex were obtained. Kassoc for the 1.2 heterocomplex was estimated to be 2 x 108 M-1 in chloroform.
- Kuykendall, Darrell W.,Anderson, Cyrus A.,Zimmerman, Steven C.
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supporting information; experimental part
p. 61 - 64
(2009/07/04)
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- Unexpectedly similar charge transfer rates through benzo-annulated bicyclo[2.2.2]octanes
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A 4-(pyrrolidin-1-yl)phenyl electron donor and 10-cyanoanthracen-9-yl electron acceptor are attached via alkyne linkages to the bridgehead carbon atoms of bicyclo[2.2.2]octane and all three benzo-annulated bicyclo[2.2.2] octanes. The σ-system of bicyclo[2.2.2]octane provides a scaffold having nearly constant bridge geometry on which to append multiple, weakly interacting benzo π-bridges, so that the effect of incrementally increasing numbers of π-bridges on electron transfer rates can be studied. Surprisingly, photoinduced charge transfer rates measured by transient absorption spectroscopy in toluene show no benefit from increasing the number of bridge π-systems, suggesting dominant transport through the σ-system. Even more surprisingly, the significant changes in hybridization undergone by the σ-system as a result of benzo-annulation also appear to have no effect on the charge transfer rates. Natural Bond Orbital analysis is applied to both σ- and π-communication pathways. The transient absorption spectra obtained in 2-methyltetrahydrofuran (MTHF) show small differences between the benzo-annulated molecules that are attributed to changes in solvation. All charge transfer rates increase significantly upon cooling the MTHF solutions to their glassy state. This behavior is rationalized using combined molecular dynamics/electronic structure trajectories.
- Goldsmith, Randall H.,Vura-Weis, Josh,Scott, Amy M.,Borkar, Sachin,Sen, Ayusman,Ratner, Mark A.,Wasielewski, Michael R.
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p. 7659 - 7669
(2008/12/22)
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- EPR and ENDOR Investigations of Dynamic Processes in Sterically Overcrowded Phenoxyl-Type Galvinoxyl Radicals
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The syntheses of tert-butylgalvinol with perdeuteriated tert-butyl groups and 1,4-bicyclooctanebisgalvinol are described.The EPR and ENDOR spectra of the corresponding galvinoxyl monoradicals reveal selective line broadening due to dynamic processes associated with hindered internal rotation of the phenoxy rings.Deuteration of the central tert-butyl group in tert-butylgalvinoxyl gives rise to a substantial decrease of EPR line widths, allowing the determination of the kinetic parameters by means of line-shape analyses (ΔH*=21.8 kJ/mol, ΔS*=-32 J/molK).The biradical 1,4-bicyclooctanebisgalvinoxyl exhibits strong scalar and dipolar electron interactions (D=97 MHz). KEY WORDS EPR ENDOR Galvinoxyls Deuteration Dynamic processes Biradicals.
- Gersdorff, J. von,Kirste, B.,Niethammer, D.,Harrer, W.,Kurreck, H.
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p. 416 - 424
(2007/10/02)
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- Synthetic Routs to the Piperolides, Faydenolides, Epoxypiperolides, and Related Compounds
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Syntheses of the piperolides, the faydenolides, epoxypiperolide, and related compounds are described. (+/-)-Narthogenin is also efficiently produced.
- Pelter, Andrew,Al-Bayati, Redha I. H.,Ayoub, Miqdad T.,Lewis, Wynn,Pardasani, Pushpa,Hansel, Rudolf
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p. 717 - 742
(2007/10/02)
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