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91.
Voltage gated carbon nanotube membranes 总被引:2,自引:0,他引:2
Majumder M Zhan X Andrews R Hinds BJ 《Langmuir : the ACS journal of surfaces and colloids》2007,23(16):8624-8631
Membranes composed of an array of aligned carbon nanotubes, functionalized with charged molecular tethers, show voltage gated control of ionic transport through the cores of carbon nanotubes. The functional density of tethered charge molecules is substantially increased by the use of electrochemical grafting of diazonium salts. Functionality can be forced to occur at the CNT tip entrances by fast fluid flow of an inert solvent through the core during electrochemical functionalization. The selectivity between Ru(bi-pyridine)(3)2+ and methyl viologen2+ flux is found to be as high as 23 with -130 mV bias applied to the membrane as the working electrode. Changes in the flux and selectivity support a model where charged tethered molecules at the tips are drawn into the CNT core at positive bias. For molecules grafted along the CNT core, negative bias extends the tethered molecules into the core. Electrostatically actuated tethers induce steric hindrance in the CNT core to mimic voltage gated ion channels in a robust large area platform. 相似文献
92.
Tokunaga SK Stack JO Hudson JJ Sauer BE Hinds EA Tarbutt MR 《The Journal of chemical physics》2007,126(12):124314
We have developed a source of cold LiH molecules for Stark deceleration and trapping experiments. Lithium metal is ablated from a solid target into a supersonically expanding carrier gas. The translational, rotational, and vibrational temperatures are 0.9+/-0.1, 5.9+/-0.5, and 468+/-17 K, respectively. Although they have not reached thermal equilibrium with the carrier gas, we estimate that 90% of the LiH molecules are in the ground state, X (1)Sigma(+)(v=0,J=0). With a single 7 ns ablation pulse, the number of molecules in the ground state is 4.5+/-1.8 x 10(7) molecules/sr. A second, delayed, ablation pulse produces another LiH beam in a different part of the same gas pulse, thereby almost doubling the signal. A long pulse, lasting 150 micros, can make the beam up to 15 times more intense. 相似文献
93.
Photophysical properties such as absorption and emission spectra, lifetimes, and redox potentials of eight ruthenium complexes, Ru(LL)2(MebpyCOOH)2+, where LL represents bpy, phen, Me2bpy, Me4bpy, (MeO)2bpy, (EtO)2bpy, Cl2bpy, and NO2phen, have been measured. The acid dissociation constants of ground and excited states have been determined. The ground-state pKa values were obtained from the pH dependence of the complex absorbance changes. The excited-state pKa* values were extracted from the emission titration curve and corrected for the excited-state lifetime of both protonated and deprotonated species. The largest DeltapKa, pKa*-pKa, found for Ru(Me2bpy)2(MebpyCOOH)2+ and Ru(Me4bpy)2(MebpyCOOH)2+ of 1.7 indicate that MebpyCOOH gains most of the MLCT excited-state electron. The big negative DeltapKa found for Ru(Cl2bpy)2(MebpyCOOH)2+, -4.2, clearly indicates the metal-to-ligand charge transfer to the Cl2bpy ligands. 相似文献
94.
We demonstrate an optical processor based on spectral hole burning (SHB) that maps the carrier frequency into the time domain and the pulse repetition frequency (PRF) into the spatial domain by illuminating an SHB crystal with a signal beam that is scanned by a tilting mirror across a slice of the crystal. This time-to-space mapping makes it possible to measure signal envelopes with a resolution of . A signal with a pulsed envelope engraves a vertical absorption grating with a spatial periodicity given by the product of the PRF and the scan velocity. Reading the grating, which the crystal stores for up to T1, with a collimated beam yields orders diffracted at angles proportional to the PRF, which are Fourier-transformed to produce spots displaced from the DC position by distances proportional to the PRF. Increasing the PRF increases the grating periodicity, causing the diffracted spots to move away from the DC position. 相似文献
95.
Dr. Brian N. Laforteza Kelvin S. L. Chan Prof. Dr. Jin‐Quan Yu 《Angewandte Chemie (International ed. in English)》2015,54(38):11143-11146
The commonly used para‐nitrobenzenesulfonyl (nosyl) protecting group is employed to direct the C? H activation of amines for the first time. An enantioselective ortho‐C? H cross‐coupling between nosyl‐protected diarylmethylamines and arylboronic acid pinacol esters has been achieved utilizing chiral mono‐N‐protected amino acid (MPAA) ligands as a promoter. 相似文献
96.
An efficient palladium-catalyzed cross-coupling of indium homoenolate with aryl halide is described. The reactions proceeded efficiently in DMA at 100 °C to afford the desired products of β-aryl ketones in moderate to good yields. Various important functional groups including COR, COOR, CHO, CN, OH, and NO(2) can be well tolerated in the protocol. 相似文献
97.
Reaction of the heteronuclear cluster RuOs3(μ-H)2(CO)13 (1) with azulene under thermal activation afforded the novel clusters RuOs3(μ-H)(CO)9(μ3,η5:η2:η2-C10H9) (3) and Ru2Os3(μ-H)2(CO)13(μ-CO)(μ3,η5:σ2-C10H8) (5a), with 4,6,8-trimethylazulene to give RuOs3(μ-H)(CO)8(μ-CO)(μ,η5:η4-C10H6Me3) (4) and Ru2Os3(μ-H)2(CO)13(μ-CO)(μ3,η5:σ2-C10H5Me3) (5b), and with guaiazulene to give Ru2Os3(CO)11(μ3,η5:η3:η3-C10H5Me2iPr) (6), respectively. In 3–5, cluster-to-ligand hydrogen transfer appears to have taken place, with the organic moiety capping a trimetallic face in 3, bridging a metal–metal bond in 4 and via a μ3,η5:σ2 bonding mode in 5a and 5b. Cluster 6 contains a trigonal bipyramidal metal framework with the guaiazulene ligand over a triangular metal face. All five clusters have been completely characterised, including by single-crystal X-ray diffraction analysis. 相似文献
98.
99.
Xiaoxi Hu Penghui Li Kelvin W. K. Yeung Paul K. Chu Shuilin Wu ZuShun Xu 《Colloid and polymer science》2011,289(13):1459-1468
A complex of Tb3+, acrylic acid (AA), and 1, 10-phenanthroline (Phen) was synthesized. The structure and fluorescence of Tb(AA)3Phen·H2O was characterized with elemental analysis, FT-IR, and fluorescence spectroscopy. A novel copolymer containing rare earth
complex, poly (METAC-co-NIPAm-co-Tb(AA)3Phen·H2O) (PMNTb), was prepared by free radical copolymerization in methanol with azodiisobutyronitrile (AIBN) as initiator. 1H NMR, fluorescence spectroscopy, UV-vis spectroscopy, and TEM were used to characterize this copolymer. The interaction of
PMNTb with DNA was studied by fluorescence spectroscopy, UV-vis spectroscopy, and agarose gel electrophoresis. The results of fluorescence,
UV-vis absorption, and agarose electrophoresis indicated that the PMNTb could interact with DNA in an electrostatic bonding mode and the bonding constant was 3.4 × 105 L mol−1. The TEM observation showed that the PMNTb could form micelles in water solution; the efficient complexation of PMNTb with DNA occurred. The results of in vitro cytotoxicity indicated that PMNTb had good biocompability. These results laid the foundation for the further study in potential gene detective reagent and
gene delivery carrier. 相似文献
100.
Y Wang L Davidow AC Arvanites J Blanchard K Lam K Xu V Oza JW Yoo JM Ng T Curran LL Rubin AP McMahon 《Chemistry & biology》2012,19(8):972-982
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