主次双波长光度法测定水体中的铁

人体所摄取的铁主要来自饮食之中。目前测定铁的主要方法有 :Ｋ2 Ｃｒ2 Ｏ7法、单波长分光光度法、极谱催化法等[1～ 3] 。本文采用一种新型主次双波长光度法测定水中的Ｆｅ(Ⅱ ) ,目的在于研究一种简便、快速、实用的测定水中铁的新方法。由于该方法采用了两个波长测定 ,抵消了实验条件变化对测定结果的影响 ,从而提高了方法的准确度 ,降低了检出限。1　实验部分1 1　实验原理任一显色体系 ,吸光度Ａ和照射波长λ及被测物质浓度ｘ之间存在如下关系[4] :Ａ +Ｋ =Ｋ1 λ(-ｙ)ｙ =αｘβ ( 1 )　　　ＡＰ+ＫＡＳ+Ｋ=( λＰλＳ) -ｙｙ =αｘ…     

锂离子二次电池正极材料镍酸锂的量子化学研究

利用周期性体系的Hartree-Fock方法计算了以LiC6／LiNiO2锂离子二次电池的平均电压，结果与实验值相差 15％。计算表明，NiO2中嵌入一个Li原子变成LiNiO2后，负电荷主要从Li转移到O上，转移到Ni上的负电荷仅约20％，讨论了其对Jahn-Tell效应的影响。以Li0.5NiO2作为嵌锂中间物的代表，研究了锂离子的可能迁移路径。通过对NiO2和LiNiO2的电子态密度的计算，研究了NiO2在嵌锂过程中的能带变化及其对电极的电化学性质的影响。     

GRAFTED STYRENE-DIVINYLBENZENE COPOLYMERS CONTAINING BENZALDEHYDES AND THEIR WITTIG REACTIONS WITH VARIOUS PHOSPHONIUM SALTS

A chloromethylated styrene-divinylbenzene copolymer support system functionalized with 4-benzaldehyde and 2-benzaldehyde was prepared.The degree of functionalization with aldehyde groups is well suited for the subsequent use of the products as Wittig reagents.The polymer bound aldehyde was reacted with Wittig reagents to give olefin groups grafted on styrene-divinylbenzene copolymers.The reactions were carried out in phase transfer catalysis conditions.A simple procedure for the calculation of the degree of functionalization and the statistical modeling of the structural repetitive unit of the copolymer are reported.     

苯并咪唑衍生物的合成、晶体结构及量子化学计算

合成了两种苯并咪唑衍生物:2-苄基-苯并咪唑(1)和1-苄基-2-苯基-苯并咪唑(2).用元素分析、红外光谱和核磁共振氢谱对产物进行了表征,并且测定了它们的单晶结构.化合物1属正交晶系,空间群Pbca, a=0.93783(6) nm, b=0.97155(6) nm, c=2.49187(16) nm, V=2.2705(2) nm3, Dc=1.218 g/cm3, Z=8, F(000)=880, μ=0.073 mm-1, R=0.0816, wR=0.1698, GOF=0.948.化合物2属单斜晶系,空间群P21/c, a=0.60272(12) nm, b=1.7059(3) nm, c=1.5257(3) nm, β=91.45(3)°, V=1.5682(5) nm3, Dc=1.204 g/cm3, Z=4, F(000)=600, μ=0.071 mm-1, R=0.0730, wR=0.1215, GOF=1.191.采用量子化学方法,在B3LYP/6-31G·水平上计算了标题化合物1和2的优化构型、电荷分布和热力学函数.     

烷氧桥联混合配位的双核铜配合物的合成、结构及量子化学计算

0IntroductionThere has been intensive interests in the past fewyears for planar Cu-(μ-OR)-Cu dinuclear systems inwhichμ-OR=OH-,MeO-,EtO-[1￣5],especially for themagnetic behavior of planar[N2Cu(μ-OH)]systemsand the magneto-structural correlation between theangle Cu-O-Cu and the magnetical exchange parame-ter J[6,7].Some hydroxo-bridged Cu!compounds alsohave catalytic activity[8].In addition,low-molecular-weight Cu!coordination compounds with nitrogen-containing donors have frequent…     

H＋NF_2→NF（α）＋HF反应的从头算研究

本文用量子化学从头算法对Ｈ＋ＮＦ_２→ＮＦ（α）＋ＨＦ反应进行了理论研究，采用ＭＰ_２（ＦＵＬＬ）／６－３１Ｇ（ｄ）方法计算了反应物、产物、中间体和过渡态的构型参数和振动频率，然后用Ｇａｕｓｓｉａｎ－２理论计算了各物种的精确能量，计算结果表明：反应在单重态势能面上进行，电子激发态ＮＦ（α）通过复合－消除机理产生，用Ｇ２理论计算２９８Ｋ下反应的焓变为－１１９．４ｋＪ／ｍｏｌ，过渡态比反应物能量低９８．４ｋＪ／ｍｏｌ．中间体ＨＮＦ２是势能面的最低点，比反应物的能量低３１３．５ｋＪ／ｍｏｌ．     

Accompanying coordinate expansion formulas derived with the solid harmonic gradient

A series of accompanying coordinate expansion (ACE) formulas for calculating the electron repulsion integral (ERI) over both generally and segmentally contracted solid harmonic (SH) Gaussian-type orbitals (GTOs) can be rederived by the use of the modified operator (called solid harmonic gradient here) of the spherical tensor gradient of Bayman and the reducing solid harmonic gradient defined in this article. The final general formulas contain the reducing mixed solid harmonics defined in a previous article [Ishida, K. J Chem Phys 1999, 111, 4913] and the reducing triply mixed solid harmonics defined previously [Ishida, K. J Chem Phys 2000, 113, 7818]. Each general formula in the series is named ACEb1k1, ACEb2k3, or ACEb3k3. New general algorithm can be obtained inductively from the general formula named ACEb2k3, in addition to the previously developed ACEb1k1 and ACEb3k3. For calculating ERI practically, we select one of these ACE algorithms, as it gives the minimum floating-point operation (FLOP) count. Theoretical assessment by the use of the FLOP count is performed for the (LL/LL) class of ERIs over both generally and segmentally contracted SH-GTOs (L = 1-3). It is found that the present ACE is theoretically the fastest among all rigorous methods in the literature.     

Terreusinone, a novel UV-A protecting dipyrroloquinone from the marine algicolous fungus Aspergillus terreus

A novel chiral dipyrrolobenzoquinone derivative, terreusinone (1), has been isolated as a potent UV-A protectant from the marine algicolous fungus Aspergillus terreus. The structure and absolute stereochemistry of the new compound was established by spectral interpretation, Horeau's method and quantum chemistry calculations as 2,6-bis[(1R)-1-hydroxyisobutyl]-1H,5H-pyrrolo[2,3-b]indole-4,8-dione (1). Compound 1 exhibited a UV-A absorbing activity with ED₅₀ value of 70 μg/mL.     

Two-Temperature Transport Coefficients in Argon–Hydrogen Plasmas—II: Inelastic Processes and Influence of Composition

Recently, a two-temperature transport properties theory has been proposed that retains the coupling between electrons and heavy species in thermal plasmas where the kinetic temperature of electrons Te can be different from that of heavy species Th. This paper is devoted to the application of this approach to an argon–hydrogen mixture at atmospheric pressure, taking into account inelastic processes and considering chemical equilibrium. In this second part are studied: the development of a new method to calculate the reaction thermal conductivity (inelastic collisions) in a non-equilibrium (two-temperature) plasma taking into account the coupling between electrons and heavy species; the influence of the composition calculation methods comparing the modified equilibrium constant method used in part 1 to the stationary kinetic calculation one; the influence on the transport properties (, , ) of the composition calculation method and non-equilibrium parameter =T_e/T_h.The different plasma compositions obtained either through an equilibrium constant or a stationary kinetic method are first compared and, for example, for =1.6, a discontinuity at T_e=11,000 K and an ionization delay are observed in stationary kinetic calculation, relative to the equilibrium constant method. Electrical conductivity, viscosity as well as thermal conductivity, including the translational, internal and reactional contributions, are calculated up to 25,000 K. It is shown that the plasma composition has a strong influence on transport coefficients, inducing shifts or discontinuities in the curves of transport coefficients, depending on the chosen method of calculation.