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91.
Jingjing Xu Yidong Lu Baohong Liu Chunhe Xu Jilie Kong 《Journal of Solid State Electrochemistry》2007,11(12):1689-1695
An ultrathin, ordered, and packed protein film, consisting of the 2-mercaptoacetic acid (MAA), polydimethyldiallylammonium
chloride (PDDA), and wild-type (WT) photosynthetic reaction center (RC; termed as WT-RC) or its pheophytin (Phe)-replaced
counterpart (termed as Phe-RC), was fabricated by self-assembling technique onto gold electrode for facilitating the electron
transfer (ET) between RC and the electrode surface. Near-infrared (NIR)-visible (Vis) absorption and fluorescence (FL) emission
spectra revealed the influence of pigment substitution on the cofactors arrangement and excitation relaxation of the proteins,
respectively. Square wave voltammetry (SWV) and photoelectric tests were employed to systematically address the differences
between the WT-RC films and mutant ones on the direct and photo-induced ET. The electrochemical results demonstrated that
ET initiated by the oxidation of the primary donor (P) was obviously slowed down, and the formed P+ had more population as well as more positive redox potential in the Phe-RC films compared with those in the WT ones. The
photoelectrochemical results displayed the dramatically enhanced photoelectric performances of the mutant ones, further suggesting
the slow-down formation of final charge-separated state in Phe-RC. The functionalized protein films introduced in this paper
provided an efficient approach to sensitively probe the redox cofactors and ET differences resulting from only minor changes
in pigment arrangement in the pigment–protein complex. The favored ET process observed for the membrane proteins RC was potentially
valuable for a deep understanding of the multi-step biological ET process and development of versatile bioelectronic devices. 相似文献
92.
The effects of atomic multipole moments obtained by the potential-derived method on hydrogen bonding
A potential-derived atomic multipole method called the cumulative potential-derived atomic multipole method is developed, with which electrostatic atomic multipole moments are derived by fitting the molecular electric potential in a cumulative way. It is applied to the hydrides of N , O , F , S , Cl , and methanol and the hydrogen-bonded dimers formed between them. The relationship between atomic multipole moments and molecular charge distributions is found. The structures calculated with Buckingham's electrostatic model are in good agreement with experiments. The phenomena of nonlinear structures of most H -bonded complexes—the deviations of symmetry axes of electron donors from H bonds—and correct distinguishing between two alternative structures are attributed to atomic dipole and quadrupole moments. Compared with other methods, this method has a quantitative and qualitative advantage and simple algorithm. The main conclusion is that the atomic multipole moments play a substantial role, although a potential-derived charge model was deemed sufficient previously. © 1993 John Wiley & Sons, Inc. 相似文献
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95.
8—氮鸟嘌呤的极谱伏安行为 总被引:4,自引:0,他引:4
用循环伏安法(CV)、电流采样极诸法(SCP,即TAST)、常规脉冲极谱法(NPP)、微分脉冲极谱法(DPP)、线性扫描伏安法(LSV)、Osteryoung方波伏安法(OSWV)和计时库仑法(CC)等电化学技术研究了抗癌药物8-氮鸟嘌呤(8-azaguanine,guanazolo,简称8-AG)的极谱伏安行为.在 0. 1mol/L H2SO4底液中,8-AG有一良好的还原峰,峰电位(Ep)在-0. 95V(vs.Ag/AgCl,下同)附近,8-AG浓度在4×10-6~8×10-4mol/L范围内.峰高与浓度有良好的线性关系,线性相关系数r=0.9999~0.9910,检出限为1× 10-6mol/L.实验证明了该峰具有吸附性.本文提出了电极反应机理,它包括:酸性介质中8-AG的质子化、质子化的8-AG在汞电极上吸附以及完全不可逆的两电子还原过程.同时用量子化学计算方法(全略微分重叠法即CNDO/2)对8-AG和鸟嘌呤的各原子的净电荷以及Wiberg键级进行了计算,从理论上解释了8-AG的电化学还原机理。 相似文献
96.
Imamura T Zhang W Horiuchi H Hiratsuka H Kudo T Obi K 《The Journal of chemical physics》2004,121(14):6861-6867
A laser-induced fluorescence spectrum was observed in the 500-560 nm region when a mixture of 1,4-cyclohexadiene and oxalyl chloride was photolyzed at 193 nm. The observed excitation spectrum was assigned to the A (2)A(2)<--X (2)B(1) transition of the cyclohexadienyl radical c-C6H7, produced by abstraction of a hydrogen atom from 1,4-cyclohexadiene by Cl atoms. The origin of the A<--X transition of c-C(6)H(7) was at 18 207 cm(-1). From measurements of the dispersed fluorescence spectra and ab initio calculations, the frequencies of several vibrational modes in both the ground and excited states of c-C(6)H(7) were determined: nu(5)(C-H in-plane bend)=1571, nu(8)(C-H in-plane bend)=1174, nu(10)(C-C-C in-plane bend)=981, nu(12)(C-C-C in-plane bend)=559, nu(16)(C-C-C out-of-plane bend)=375, and nu(33)(C-C-C in-plane bend)=600 cm(-1) for the ground state and nu(8)=1118, nu(10)=967, nu(12)=502, nu(16)=172, and nu(33)=536 cm(-1) for the excited states. 相似文献
97.
HUANG Wei-Ping ZHANG Xin-Jie WU Shi-HuaMA Shu-Yin ZHANG Shu-Ji ZHAO Wei-Jun 《天然气化学杂志》1997,6(3):252-257
IntroductionIn1962,N.V.Kutepow'SgroupfirstusedcomplexesofFe,CoandNiascatalyststocatalyzecarboXylationofethanoltopreparepropanoicacidanditsderivants.Thereactionpressurewashighandtheyieldwaslow.LateronPaulalsandhiscolleagueusedabC13andiodineascatalyst,which… 相似文献
98.
1—酰基—4—氯环己烷与取代芳烃的区域与立体选择性反应 总被引:2,自引:0,他引:2
从环己烯合成了1-酰基-4-氯环己烷,发现在其在AlCl3催化与苯,氯苯,溴苯等优先生成反式1-芳基-4-酰基环己烷,与联苯反应时选择性较差。 相似文献
99.
100.
ELECTROCHEMICAL POLYMERIZATION OF ANILINE IN PHOSPHORIC ACID AND THE PROPERTIES OF POLYANILINE 总被引:1,自引:0,他引:1
The behavior of the electrochemical polymerization of aniline in a weak acid, phosphoric acid, is very similar to that in strong acids, i.e. its polymerization rate increases quickly with the electrolysis time. The FTIR spectra of polyaniline samples synthesized in phosphoric acid indicate that the counter ion H2PO4^- is present in both the oxidized form and the reduced form of polyaniline. The counter ion plays an important role in adjusting the pH value at the electrode surface of polyaniline during the oxidation and reduction processes. As a result, a pair of redox peaks still appear in cyclic voltammograms of polyaniline in a solution of sodium sulfate of pH 5.5 and in a solution of NaH2PO4 of pH 7.0,respectively, at low potential scan rate; and the color of polyaniline film also changes with applied potential at pH 7.0. Thus,the pH region for the electrochemical activity and the electrochromism of polyaniline is extended to pH 5.5 for a solution of sodium sulfate and to pH 7.0 for a solution of NaH2PO4. The conductivity of polyaniline is 3.3 S cm^-1, depending on the concentration of phosphoric acid used in the stage of polymerization of aniline. The result of elemental analysis of polyaniline is presented here. 相似文献