Theoretical study of proton coupled electron transfer reaction in the light state of the AppA BLUF photoreceptor

The BLUF (blue light sensor using flavin adenine dinucleotide) domain is widely studied as a prototype for proton coupled electron transfer (PCET) reactions in biological systems. In this work, the photo-induced concerted PCET reaction from the light state of the AppA BLUF domain is investigated. To model the simultaneous transfer of two protons in the reaction, two-dimensional potential energy surfaces for the double proton transfer are first calculated for the locally excited and charge transfer states, which are then used to obtain the vibrational wave function overlaps and the vibrational energy levels. Contributions to the PCET rate constant from each pair of vibronic states are then analyzed using the theory based on the Fermi's golden rule. We show that, the recently proposed light state structure of the BLUF domain with a tautomerized Gln63 residue is consistent with the concerted transfer of one electron and two protons. It is also found that, thermal fluctuations of the protein structure, especially the proton donor-acceptor distances, play an important role in determining the PCET reaction rate. © 2018 Wiley Periodicals, Inc.     

C75N+位置异构体的电子结构和光谱研究

杂原子的介入可改变纯碳笼的电子结构, 使其在超导、光电子器件及有机铁磁体等方面得到应用, 还可改善其氧化还原性能, 提高反应活性, 因而引起人们的研究兴趣[1～3]. Averdung[1]研究了C59N+与H的反应, 用质谱检测到C59NH和C59NH+2, 并用AM1方法优化其结构; Lamparth[2]以双氮杂富勒烯为前体, 合成了C59N+和C69N+, 测定中间体的 1H NMR谱、 UV谱及产物的FAB质谱, 并用 15N标记法证实了最强的碎片峰是N原子进入母体碳笼骨架所致. Diederich[3]观察到C76氮化物的FAB质谱信号, 但未给出进一步信息. 本文用INDO系列方法对氮杂富勒烯C75N+位置异构体的结构和稳定性进行理论研究, 找出最稳定的异构体, 计算其电子吸收光谱, 为实验室合成分离提供理论依据.     

On-column sample preconcentration in electrokinetic chromatography by sweeping with polymeric pseudo-stationary phases

This paper demonstrates in a practical manner the on-column preconcentration of hydrophobic solutes, such as quinine, alkyl phenones, and progesterone, by the sweeping mechanism using polymeric surfactants with highly acidic ionic head groups. The sulfonated and sulfated copolymers used showed high electrophoretic mobilities, high solubility, and good stability in organic/aqueous solutions with low pH values. More than 1000-fold increase in signal was observed for quinine, heptanophenone, and progesterone using sweeping in reversed-flow electrokinetic chromatography at low pH. The detection limit of quinine can be lower than 42 ppb (ng/mL) using a diode array UV detector. Quinine, a cationic hydrophobic solute with a relatively high retention factor, can be concentrated 5800 to 10,000-fold and separated from other hydrophobic solutes using a separation buffer containing a relatively high concentration of organic modifier. Under these conditions, detection of 12.5 ppb of quinine with a signal-to-noise ratio of 15 is achieved. The retention times and peak heights of hydrophobic solutes are shown to be reproducible.     

New Approach to Synthesis of 6,7—Dimethoxyisatin

A new approach to synthesis of 6,7-dimethoxyisatin is reported.2-nitro-3,4-dimethoxy mandelonitrile in glacial acetic acid was treated with the solution of stannous chloride in hydrochloric acid to give 6,7-dimethoxyisatin in a high yield.     

A New Cyclohexene Oxide from Uvaria tonkinensis var. subglabra

A new compound, subglain B, was isolated from the stems of Uvaria tonkinensis var.subglabra and its structure was identified as 1S, 2R, 3S, 6R-1-benzoyloxymethylene-1,2-dihydroxy-3-benzoyloxy-6-chlorocyclohex-4-ene (1), by spectral evidences.     

Hydrothermal Synthesis and Structure of a New 3D Lanthanide—Carboxylate Framework,[La（btec）1／2（H2btec）1／2（H2O）]n（H4btec=1,2,4,5—Benzeneteracarboxylic acid）

The title complex, [La(btec)_1/2(H₂btec)_1/2 (H₂O)]_n (H₄btec= 1, 2,4,5‐benzenetetracarboxylic acid) (1) was synthesized by the hydrothermal reaction of 1,2,4,5‐benzenetetracarboxylic dianhydride with La(NO₃)₃·6H₂O in H₂O, and crystallizes in the triclinic system, space group P‐1 with a = 0.64403(3) nm, b = 0.94500(4) nm, c = 0.96380(5) nm, a = 88.535(2)°, β = 100.314(2)°, γ = 76.6470(10)°, V = 1.60968(10) nm³, Z = 2, and final R = 0.0274, R_w = 0.0735. In 1, each La(m) ion is coordinated by eight oxygen atoms from six carboxylate groups and one coordinated water molecule. Two different coordination modes of H₄btec were present in the structure, one of which contains two protonated carboxylate groups to balance the charge.     

掺碳球形Ni(OH)2的特性

电子导电剂;充放电特性;掺碳球形Ni(OH)2的特性     

不可逆电活性药物米托蒽醌与脱氧核糖核酸的相互作用

研究了抗癌新药米托蒽醌(MXT)的电化学行为及与脱氧核糖核酸(DNA)的相互作用，推导了适用于研究不可逆电活性分子与DNA相互作用的电化学公式，运用该公式可以简便、快速地测定靶向分子与DNA的结合常数和结合位点数。实验发现，MXT与小牛胸腺DNA的结合以蒽醌母核的嵌插作用为主，同时，烃氨基侧链与骨架磷酸基团之间的静电吸引对母核起稳定作用，使化合物易于嵌入DNA的平面结构。MXT与DNA相互作用引起的峰电流的变化可以用于分析测定DNA。     

Tetra­aqua(2,2′‐bi­pyridine)­nickel(II) terephthalate

The reaction of nickel(II) nitrate with terephthalic acid and 2,2′‐bi­pyridine in di­methyl­form­amide solution gives the title complex, [Ni(C₁₀H₈N₂)(H₂O)₄](C₈H₄O₄). The Ni^II ion is octahedrally coordinated to one 2,2′‐bi­pyridine and four water mol­ecules and does not coordinate to the terephthalate anion. Hydro­gen bonds between the terephthalate anions and the [Ni(2,2′‐bipy)(H₂O)₄]²⁺ cations produce a two‐dimensional hydrogen‐bonding architecture with double sheets.