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921.
922.
Biqing Bao Lihui Yuwen Xiaowei Zhan Lianhui Wang 《Journal of polymer science. Part A, Polymer chemistry》2010,48(15):3431-3439
New water‐soluble hyperbranched polyfluorenes bearing carboxylate side chains have been synthesized by the simple “A2 + B2 + C3” protocol based on Suzuki coupling polymerization. The linear polyfluorene analogue LPFA was also synthesized for comparative investigation. The optical properties of the neutral precursory polymers in CHCl3 and final carboxylic‐anionic conjugated polyelectrolytes in buffer solution were investigated. The obtained hyperbranched polyelectrolyte HPFA2 with lower content of branch unit (2%) showed excellent solubility and high fluorescence quantum yield (?F = 89%) in aqueous solution. Fluorescence quenching of HPFA2 by different metal ions was also investigated, the polyelectrolyte showed high selectivity for Hg2+ and Cu2+ ions relative to other various metal ions in buffer solution. The Stern‐Volmer constant Ksv was determined to be 0.80 × 106 M?1 for Hg2+ and 3.11 × 106 M?1 for Cu2+, respectively, indicating the potential application of HPFA2 as a highly selective and sensitive chemosensor for Hg2+ and Cu2+ ions in aqueous solution. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 3431–3439, 2010 相似文献
923.
Organic small molecules(TPA-BT3T,TPA-PT3T,and TPA-DFBT3T)using triphenylamine as a donor unit,terthiophene as a bridge,and benzo-2,1,3-thiadiazole(BT),[1,2,5]thiadiazolo[3,4-c]pyridine(PT)or 5,6-difluorobenzo[c][1,2,5]thiadiazole(DFBT)as an acceptor unit were designed and synthesized through Suzuki coupling reactions.These molecules exhibited good thermal stability with decomposition temperatures over 380°C and broad absorption from 300 to 700 nm.Photovoltaic devices were fabricated with these small molecules as donors and PC71BM as an acceptor.The TPA-BT3T based devices exhibited a power conversion efficiency of 2.89%,higher than those of the TPA-PT3T-and TPA-DFBT3T-based devices(1.34%and1.54%respectively).The effects of electron-withdrawing units on absorption,energy level,charge transport,morphology,and photovoltaic properties also were investigated. 相似文献
924.
Ling-Ling Zhang You-Bang Zhan Qun-Yong Zhang 《International Journal of Theoretical Physics》2009,48(10):2971-2976
We present a controlled quantum secure direct communication protocol by using cluster states via swapping quantum entanglement
and local unitary operation. In the present scheme, the sender transmit the secret message to the receiver directly and the
secret message can only be recovered by the receiver under the permission of the controller. 相似文献
925.
926.
Xiu Lan Xin Guowei Yang Zhan Ping Gou Ji Hong Yao Rong Lan Xiao Chi Ma 《Magnetic resonance in chemistry : MRC》2010,48(2):164-167
Five hydroxylated derivatives of glycyrrhetinic acid by Mucor polymorphosporus were isolated. Among them, 6β, 7β‐dihydroxyglycyrrhentic acid (2) and 27‐hydroxyglycyrrhentic acid (3) are new compounds. Their chemical structures were identified by spectral methods including 2D‐NMR. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
927.
We have run several molecular dynamics (MD) simulations on zinc-containing phosphotriesterase (PTE) with two bound substrates, sarin and paraoxon, and with the substrate analog diethyl 4-methylbenzylphosphonate. A standard nonbonded model was employed to treat the zinc ions with the commonly used charge of +2. In all the trajectories, we observed a tightly bound water (TBW) molecule in the active site that was coordinated to the less buried zinc ion. The phosphoryl oxygen of the substrate/inhibitor was found to be coordinated to the same zinc ion so that, considering all ligands, the less buried zinc was hexa-coordinated. The hexa-coordination of this zinc ion was not seen in the deposited X-ray pdb files for PTE. Several additional MD simulations were then performed using different charges (+1, +1.5) on the zinc ions, along with ab initio and density functional theory (DFT) calculations, to evaluate the following possibilities: the crystal diffraction data were not correctly interpreted; the hexa-coordinated zinc ion in PTE is only present in solution and not in the crystal; and the hexa-coordinated zinc ion in PTE is an artifact of the force field used. A charge of +1.5 leads to a coordination number (CN) of 5 on both zinc ions, which is consistent with the results from ab initio and DFT calculations and with the latest high resolution X-ray crystal structure. The commonly used charge of +2 produces a CN of 6 on the less buried zinc. The CN on the more buried zinc ion is 5 when the substrate/inhibitor is present in the simulation, and increases to 6 when the substrate/inhibitor is removed prior to the simulation. The results of both of the MD and quantum mechanical calculations lead to the conclusion that the zinc ions in the PTE active site are both penta-coordinated, and that the MD simulations performed with the charge of +2 overestimate the CN of the zinc ions in the PTE active site. The overall protein structures in the simulations remain unaffected by the change in zinc charge from +2 to +1.5. The results also suggest that the charge +1.5 is the most appropriate for the molecular dynamics simulations on zinc-containing PTE when a nonbonded model is used and no global thermodynamic conclusion is sought. We also show that the standard nonbonded model is not able to properly treat the CN and energy at the same time. A preliminary, promising charge-transfer model is discussed with the use of the zinc charge of +1.5. 相似文献
928.
Wang J Even MA Chen X Schmaier AH Waite JH Chen Z 《Journal of the American Chemical Society》2003,125(33):9914-9915
In this Communication, we demonstrate the novel observation that it is feasible to collect amide signals from polymer/protein solution interfaces in situ using sum frequency generation (SFG) vibrational spectroscopy. Such SFG amide signals allow for acquisition of more detailed molecular level information of entire interfacial protein structures. Proteins investigated include bovine serum albumin, mussel protein mefp-2, factor XIIa, and ubiquitin. Our studies indicate that different proteins generate different SFG amide signals at the polystyrene/protein solution interface, showing that they have different interfacial coverage, secondary structure, or orientation. 相似文献
929.
Wei Bin Bai Zhi Yuan Chen Cai Mao Zhan 《中国化学快报》2007,18(1):76-78
Dihexylfluorene and N-butylcarbazole were copolymerized by solid-state oxidative coupling polymerization in the presence of anhydrous FeCl_3 at room temperature.The solid-state films of the copolymers emitted blue light after heating at 150℃in air for 24 h,no red-shifted emission was observed by fluorescence spectroscopy. 相似文献
930.