英语翻译不要那种在线翻译的结果,好的在追加分200分.

英语翻译不要那种在线翻译的结果,好的在追加分200分.
英语翻译
不要那种在线翻译的结果,好的在追加分200分.

英语翻译不要那种在线翻译的结果,好的在追加分200分.
Computational chemistry that can predict the spectra of a variety of compounds that cannot be obtained as
　　pure compounds was used to study the highly sensitive detection of bromate in ion chromatography. Several
　　possible ions, molecules, and their complexes were constructed by a molecular editor, and optimized by
　　molecular mechanics (MM2) and MOPAC (PM3) calculations. The possible electronic spectra of these
　　ions, molecules, and complexes were then obtained by the ZINDO (INDO)-Vizualyzer in the CAChe program.
　　The lambda maximum (ìmax) of the spectra and the transition dipole were calculated using the ProjectLeader
　　program. The comparison of the experimental and predicted results indicated that Br3
　　- was the probable
　　reaction product, and that NO2
　　- and ClO- accelerated the reaction.
　　1. INTRODUCTION
　　Bromate is considered a carcinogen and the World Health
　　Organization (WHO) has recommended the provisional
　　bromate guideline value of 25 mg/L, which is associated with
　　an excess lifetime cancer risk of 7 \2 10-5, because of the
　　limitations in the available analytical and treatment methods.1
　　A highly sensitive analytical method was therefore developed.
　　Bromate in ozonized water was detected with very
　　high sensitivity by ion chromatography with a postcolumn
　　reaction detection using ultraviolet absorption. With the
　　addition of nitrite for the postcolumn reaction, the sensitivity
　　was improved 738-fold. The detection limit was 0.35 mg/
　　L, and the linear range was >4 orders of magnitude, from
　　0.5 to 10 mg/L.2 The addition of ClO- improved the
　　sensitivity 327-fold.2
　　Chiu and Eubanks3 examined bromide spectrophotometrically;
　　they proposed a reaction mechanism and suggested
　　that the end product is tribromide.3 The proposed reactions
　　are as follows:
　　In addition, bromate and chlorate were determined by
　　potentiometric titration after reduction with sodium nitrite.4
　　Sodium nitrite was added in sodium bromide for the on-line
　　hydrobromic acid generator in this system, and highly
　　sensitive detection was achieved.2 However, the reaction
　　mechanism and the final product have not been determined.
　　Tuchler et al.5 studied bimolecular interactions and directly
　　detected the internal conversion involving Br(2P1/2) + I2
　　initiated from a van der Waals dimer. The reaction complex
　　was formed from a van der Waals dimer precursor, HBrâI2.
　　The resulting product, highly vibrationally excited molecular
　　I2, was monitored by resonance-enhanced multiphoton
　　ionization combined with time-of-flight mass spectroscopy.
　　The HBr constituent of the precursor HBrâI2 was photodissociated
　　at 220 nm. The H atom departed instantaneously,
　　allowing the remaining electronically excited Br(2P1/2) to
　　form a collision complex, (BrI2)*, in a restricted region along
　　with the Br + I2 reaction coordinate determined by precursor
　　geometry. Sims et al.6 reported the fentosecond real-time
　　probing of bimolecular reaction Br + I2, and summarized a
　　number of trihalogen intermediates observed in matrix
　　isolation studies.
　　Computational chemistry can predict the electronic spectra
　　of a variety of compounds that cannot be obtained as pure
　　compounds. This tool was applied to study the highly
　　sensitive detection of bromate in ion chromatography.
　　Several possible ions and molecules and their complexes
　　were constructed by a molecular editor, and optimized by
　　molecular mechanics (MM2) and MOPAC (PM3 and AM1)
　　calculations. Their possible electronic spectra were then
　　obtained with the ZINDO (INDO/1)-Vizualyzer in the
　　CAChe program. The lambda maximum (ìmax) of the spectra
　　of the transition dipole were calculated using the ProjectLeader
　　program. The properties used for the calculation of
　　the molecular mechanics were bond stretch, bond angle,
　　dihedral angle, improper torsion, van der Waals, electrostatic
　　(MM2 bond dipole), hydrogen bond, and cut-off distance
　　for van der Waals interactions (9.00 Å). (van der Waals
　　interactions were updated every 50 interactions.) The
　　parameters for the MOPAC calculation were geometry search
　　* Author to whom correspondence should be sent.
　　† Health Research Foundation.
　　‡ Yokogawa Analytical Systems.
　　Br- + 3ClO- f BrO3
　　- + 3Cl- (1)
　　BrO3
　　- + 5Br- + 6H+ f 3Br2 + 3H2O (2)
　　Br2 + Br- f Br3
　　- (3)
　　J. Chem. Inf. Comput. Sci. 1998, 38, 885-888 885
　　S0095-2338(98)00084-5 CCC: $15.00 © 1998 American Chemical Society
　　Published on Web 08/14/1998
　　options (precise, minimized by NLLSQ, optimized geometry
　　by BFGS), and properties [Mulliken population, energy
　　partitioning, polarizabilities, localize, thermo, rotational
　　symmetry (C1)] in the CAChe program. The predicted data
　　were compared with those obtained experimentally.
　　2. THEORY
　　According to the Lambert-Beer law, the ratio of the
　　intensity of the light of the inlet site (Io(î)) and the outlet
　　site (I(î)) is given by the following equation:
　　That is, absorbance A ) log10I/Io ) k(î)Dx, where the molar
　　extinction coefficient (molar absorption coefficient) I ) Io
　　\2 10k(î)Dx, and k(î): molar extinction coefficient is the molar
　　absorptivity.
　　The following equation is given as the relation between
　　absorption intensity as measured experimentally and that
　　estimated theoretically:7
　　The intensity of the spectrum is given by the following
　　equation:
　　where jájjköâerjiñj2 is the transition dipole.
　　That is, molar absorptivity, k(î), is related to the transition
　　dipole. The following parameters are found in eqs 4-7: D,
　　concentration of analyte; x, pass length of light; c, light speed;
　　N, Avogadro’s constant; h, Planck’s constant; V, frequency;
　　j, excited state; i, ground state; k, Boltzmann’s constant; er,
　　transition dipole moment; and kö, polarized light vector.
　　3. RESULTS AND DISCUSSION
　　The computational chemical calculation was performed
　　by the CAChe program from Sony-Tektronix (Tokyo) using
　　a Macintosh 8100/100 personal computer. The molar
　　absorptivity of several ions, molecules, and complexes were
　　directly measured on spectra obtained by ZINDO-Visualization
　　after their conformations were optimized by MM2 and
　　MOPAC (PM3 and AM1). Their transition dipoles were
　　calculated by the ProjectLeader program using MM2
　　and MOPAC (PM3 and AM1). The values of molar
　　absorptivity and the transition dipoles are summarized in
　　Table 1. The values of their complexes with nitrite and
　　chlorite are included. The energy values of angle and van
　　der Waals obtained by the MM2 calculation are also given
　　in Table 1.
　　The relation between the transition dipole and the molar
　　absorptivity was:
　　where Y is molar absorptivity (I/mol-cm) and X is the
　　transition dipole (debye). The chromatographic sensitivity
　　is directly related to the molar absorptivity of the analytes.
　　The molar absorptivity of Br3
　　- and the Br2 + Br- complex
　　was very high, 190 000. The measurements of molar
　　absorptivity and the ìmax wavelength were not easily
　　obtained, but these values can be automatically calculated
　　using the ProjectLeader program. The Br3
　　- and the Br2 +
　　Br- complex have similar structures, as shown in Figure 1.
　　The complex between Br2 and Br- was automatically formed
　　after the optimization of the structure, and the heat of
　　formation energy value was the lowest among the analytes
　　listed in Table 1; the values were about -106 kcal/mol. The
　　value of the complex was the same as that of Br3
　　-. This
　　Table 1. Properties of Analytesa
　　analyte HOF, kcal/mol ìmax, nm td debye ma, L/mol-cm angle, kcal/mol vwv, kcal/mol
　　Br- -56.00 - - * 0.00 0.00
　　Br2 4.92 602 0.277 81 0.00 0.00
　　Br3
　　- -105.69 258 12.300 188200 0.00 0.00
　　BrO3
　　- -39.59 462 0.927 595 3.28 0.00
　　NO2
　　- -42.93 208 4.005 24660 0.00 0.00
　　ClO- -32.97 234 0.409 458 0.00 0.00
　　Br2 + NO2
　　-/1 -98.49 224 7.227 74550 0.00 -0.26
　　Br2 + NO2
　　-/2 -104.80 239 8.183 91440 0.03 -0.05
　　Br2 + NO2
　　-/3 -99.93 230 5.550 43370 0.00 -0.22
　　Br2 + Br- -105.69 258 12.327 188250 0.00 -0.36
　　Br2 + ClO-/1 -113.02 228 4.758 30670 0.00 -0.33
　　Br2 + ClO-/2 -74.52 228 10.385 148400 0.00 -0.46
　　Cl- -51.22 - - * 0.00 0.00
　　Cl2 -11.57 410 0.464 336 0.00 0.00
　　Cl3
　　- -91.06 214 10.615 168200 0.00 0.00
　　Cl2Br- -95.30 247 10.727 148760 0.00 -0.32
　　Cl2 + OCl- -87.51 243 5.220 34 0.00 -0.36
　　BrO3
　　- + NO2
　　- -51.11 209 4.117 30166 0.00 -0.75
　　I3 -85.58 221 12.738 236800 0.00 0.00
　　I2Br -87.59 229 12.276 209360 0.00 0.00
　　a HOF: heat of formation (PM3); td: transition dipole; ma: molar absorptivity; angle: dihedral angle (MM2); vwv: van der Waals energy
　　(MM2); *: molecule lacks electronic state information.
　　Y ) 1057.422X2 + 3017.582X - 2368.256
　　r2 ) 0.993 (n ) 14) (8)
　　[I(î) Io(î)] ) 10-k(î)Dx ) e-ln10âk(î)Dx (4)
　　103âln 10âc
　　Nh
　　s k(î)
　　î
　　dî ) 8ð3
　　h2
　　jájjköâerjiñj2 (5)
　　f(theoretical) ) 8ð2mî
　　3h
　　jájjköâerjiñj2 (6)
　　k(î) ) 1
　　Dx
　　log10 I/Io µ jájjköâerjiñj2 (7)
　　886 J. Chem. Inf. Comput. Sci., Vol. 38, No. 5, 1998 HANAI ET AL.
　　result indicated that Br3
　　- can be formed where Br2 and Brco-
　　exist as the BrI2 complex.5,6
　　The question arises as to how NO2
　　- and ClO- acted in
　　the reaction: did these ions form different compounds or
　　complexes with bromide or bromine for the highly sensitive
　　detection of bromate? The Br2 + NO2
　　- complex was
　　thusconstructed, and we optimized the structure by MM2
　　and PM3 calculations. The Br2 and NO2
　　- formed three types
　　of conformations, as shown in Figure 2. The structures A
　　and B were obtained as molecules and the structure C was
　　obtained as a transition state. Their energy values of heat
　　of formation are given in Table 1 as Br2 + NO2
　　-/1, Br2 +
　　NO2
　　-/2, and Br2 + NO2
　　-/3, respectively. Their heat of
　　formation energy values were low; the lowest energy value
　　was -105 kcal/mol, about the same as that of the Br2 +
　　Br- complex. The structure with the lowest energy value
　　is structure B in Figure 2. However, its molar absorptivity
　　was less than half of that of the Br2 + Br- complex. This
　　result suggested that NO2
　　- may form a complex with Br2;
　　however, such a complex may not be the final product
　　because of the low sensitivity. The ìmax wavelengths of
　　structures A, B, and C in Figure 2 were 224, 230, and 240
　　nm, respectively, and were different from that of the Br2 +
　　Br- complex and Br3
　　-, whose ìmax was 258 nm. The ìmax
　　of 258 nm was the closest wavelength to that observed
　　experimentally (265 nm). This result also suggested that
　　such a complex may not be the final product. The formation
　　of these complexes was supported by the negative values of
　　their van der Waals energy calculated by MM2 (Table 1).
　　Bromide did not form a complex with NO2
　　-. Bromide,
　　bromine, bromate, and nitrite were not highly sensitive
　　analytes, due to their low transition dipole values and ìmax
　　wavelength.
　　Another question was why the sensitivity measured in the
　　existence of ClO- was about the half of that measured in
　　the existence of NO2
　　-. The reaction processes were estimated
　　according to the proposal of Chiu and Eubanks.3
　　The value of molecular absorptivity of Cl2Br- (148 760) was
　　lower than that of Br3
　　- (188 200), and the ìmax wavelength
　　of Cl2Br- (247 nm) was also lower than that of Br3
　　- (258
　　nm). Therefore, the final sensitivity using ClO- as the
　　reaction reagent was less than that using NO2
　　-.
　　Bromate formed a complex with nitrite; however, the
　　complex may be unstable due to the high energy value of
　　the heat of formation. This complex is not a candidate for
　　the highly sensitive detection of bromate because of the low
　　transition dipole value and ìmax wavelength. Bromine can
　　form a complex with ClO-; however, the energy value of
　　heat of formation was high for a complex with a higher
　　transition dipole. This means that the Br2 + ClO- complex
　　may be not a candidate for the highly sensitive detection of
　　bromate. The results just presented indicate that the highly
　　sensitive detection of chlorate and iodinate can be achieved
　　by using the techniques employed for the bromate analysis.
　　The sensitivity of chlorate and iodinate will be 90 and 111%
　　of bromate; however, the ìmax wavelengths of Cl2Br- and
　　I2Br- are 10 and 30 nm lower, respectively, than that of
　　Br2Br-. IfCl3
　　- and I3
　　- are the final products, the specific
　　ion generator should be constructed; however, the detection
　　wavelengths of Cl3
　　- and I3
　　- are further lower than those of
　　Cl2Br- and I2Br-, and the selective detection may not be
　　easy. The computational chemical analysis of fluorate could
　　not performed due to the lack of stable electron stable
　　information for fluorate.
　　An AM1 calculation can be used to optimize these
　　structures; however, the present AM1 calculation did not give
　　complex forms because of the fixed atomic distances. The
　　ìmax wavelengths were usually shorter than that obtained
　　by PM3, and the values of molar absorptivity were smaller.
　　For example, the maximum atomic distances of Br3
　　-
　　calculated by PM3 and AM1 were 5.065 and 4.575 Å,
　　respectively. Their ìmax wavelengths and their values of
　　Figure 1. Electron density of the optimized structures of Br2 +
　　Br- complex and Br3
　　-.
　　Figure 2. Possible conformations of Br2 + NO2
　　-.
　　2BrO3
　　- + 4NO2
　　- + 4H+ f Br2 + 4HNO3 + 2H2O (9)
　　Br2 + Br- f Br3
　　- (10)
　　2BrO3
　　- + 4ClO- + 6H+ f
　　Br2 + Cl2 + 2HClO3 + 3H2O (11)
　　Br2 + Br- f Br3
　　- and Cl2 + Br- f Cl2Br- (12)可以预测有机混合物中一系列有机物色谱的计算化学能在离子色谱中进行溴离子的高灵敏度色谱分析.一些能测的离子,分子和他们的复合物分子结构能通过一个分子编辑器得到.再通过分子力学进一步优化和用MOPAC进一步计算来完善它,这些离子,分子和配和物的电子光谱就会在高度缓存程序中通过ZINDO (INDO)-Vizualyzer方法获得.那色谱和过渡偶极子的最大波长可以通过ProjectLeader程序计算出来.通过实验结果和预测结果的比较表明Br3-是可能的反应产物,而且其中的NO2-和CLO-加快了反应.
　　1. 前言
　　溴酸盐被认为是一种致癌物子和世界卫生组织已建议它的含量准则为25mg/L,这与人一生超过7*10-5 的癌症发病率有关,这是由于以前溴酸盐在有效分析和处理方法上受到限制.因此,一种高灵敏度的分析方法就发展起来了.溴酸盐在溴氧水中通过离子色谱能被精确的检测到,而离子色谱是使用紫外吸收进行柱后反应测定的.随着亚硝酸盐在柱后反应中的加入,灵敏度提高了738倍.检测线0.35mg/L,并且从0.5-10mg/L的线性范围大于四个数量级,CLO-的加入也使灵敏度提高了327倍.
　　Chiu和Eubanks审查了甲基溴光度法,他们提出了一种反应机制,并认为那最终的产物是三溴化物.
　　此外,溴和氯在减少硝酸钠加入量后可通过电位滴定法测得,溴化钠中加入硝酸钠是为了溶液中出现氢溴酸,从而获得精确的测定结果.但是,反应的机制和最终产物仍然是没有确定.图兹勒等人研究双分子的相互作用和发现内部转换Br(2P1/2) + I2开始于范德华二聚体.那反应产物形成范德华二聚体,HBr.I2.那最后产物是高聚物分子,他是通过共振性强的多光子电离法和质谱法相结合而测到的.那HBr.I2的反应产物溴化氢的键长是220nm.氢原子的瞬间离开,使得其余的电子激发Br(2P1/2),彼此发生复杂的碰撞,形成(BrI2)*.在一个限制的区域伴随着Br- + I2同样取决于反应初始条件.Sims et al,他报告了双分子反应Br- + I2方面的探究结果,总结出了反应中间体在进行分离实验研究时能被观察到.
　　计算化学可以预测混合有机物中一系列有机物的电子色谱,计算化学还应用于精确检测离子色谱中的溴.一些可测的离子,分子和配合物的分子结构通过分子编辑器能被构造出来,再通过分子力学进一步优化和用MOPAC进一步计算.那么他们的电子色谱就会在高度缓存程序中通过ZINDO(INDO)-Vizualyzer方法获得.那色谱和过渡偶极子的最大波长可以通过ProjectLeader程序计算出来.计算化学中的程序还可以计算分子的键长,键角,二面角,扭转力,范德华力,静电力,氢键和由范德华力分离的距离（9.00 Å）.用MOPAC 计算方法计算的参数在下表1,并且各种特性都通过那CAChe程序显现出来了.然后,我们预测的数据就可以和这些实验得出的数据进行比较.
　　文献第三部分：
　　2. 结果与讨论
　　计算化学的计算是由CAChe程序来完成的,这个程序是由东京的索尼泰克公司开发的,更适用于个人电脑.一些离子,分子和配合物的摩尔吸收率能在光谱中直接测量得到,而它们各自的光谱是离子,分子,配合物分子在经过进一步优化和计算后通过ZINDO-Visualization方法而得到的.那ProjectLeader程序用MM2和MOPAC方法可以计算它们的过渡偶极子.摩尔吸收率和过渡偶极子的测试值总结在表1中.它们的复合物如亚硝酸盐和亚氯酸盐的测试值也列在表1中.角度和范德华力的测试值通过MM2计算也被列在表1中.
　　摩尔吸收率和过渡偶极子的关系是：
　　Y = 1057.422X2 + 3017.582X - 2368.256
　　r2=0.993(n=14)(8)
　　其中Y是摩尔吸收率(I/mol-cm),X是过渡偶极子(debye).那色谱的灵敏度直接关系到样品的摩尔吸收率.Br3-的摩尔吸收率和Br2 + Br-配合物的摩尔吸收率都很高,大约是190000.摩尔吸收率和最大波长的大小是不容易测得的,但是这些值可以通过ProjectLeader程序自动计算出来.Br3和-Br2 + Br-配合物有类似的结构,如图1所示.
　　在Br3-和Br2 + Br-之间的复合物是在结构的优化中自动形成的,它能量中的热量值是上述表1样品中最低的.那测量值大约是-106kcal/mol.那复合物的测量值是和Br3-的值一样的.这结果表明Br3-能形成诸如BrI2之类的复合物.
　　那么问题就归于了解亚硝酸根和亚氯酸根是怎样参与反应的：这些离子之间可以形成不同的化合物吗?或者由于溴的高灵敏度能与溴化物和溴酸盐形成复合物吗?Br2 + NO2-形成的配合物被构造出来,并且我们通过MM2和PM3计算来优化那结构.那溴与亚硝酸盐就可能有三种不同的构造,这些构造都列在表2中.
　　那A和B是获得的分子,而C是过渡态.它们的热量值分别列在表1中.它们的热量值都很低,其中最低的能量值是-105kcal/mol,这能量值是和Br+Br-的能量值一样的.在表2中可以知道最低能量值的构造是B化合物的结构.然而,它的摩尔吸收率比Br2 + Br-复合物的一半还少.这结果表明亚硝酸根能和溴形成复合物；然而,由于那低的灵敏度得知这种复合物不是最终产物,A,B,C的最大波长列在表2中,一次是224,230和240nm.显然,这是和Br+Br复合物不同的.那最大波长258nm最靠近那理论波长265nm.这结果也表明了那产物不是那最终产物.这些复合物的范德华力通过MM2和PM3计算得知是负值列在表1中.溴化物不能和亚硝酸根形成复合物.溴化物,溴酸盐,溴离子和亚硝酸盐都不是高灵敏度样品,这是由于他们的最长波长和过渡偶极子决定的.