电解质在混合溶剂中的溶解度——盐-DMSO(或DMF)-惰性溶剂体系

本文测定了盐在含苯、甲苯、对二甲苯和四氯化碳的DMSO或DMF混合溶剂中的溶解度。结果符合经验公式lg(S₀/S_m)=K^φφ_Ne;对K^φ的规律作了初步讨论。     

关于盐在混合溶剂中的活度系数和溶剂化

李芝芬等人^[1]测定了盐在甲醇混合溶剂中的溶解度,得到经验公式: lg(S_o/S_s-kX_Ne)(1)式中S_o和S_s分别为盐在甲醇和混合溶剂中的溶解度,X_Ne为第二组分溶剂的摩尔分数,k为第二介质常数。     

电解质在非水混合溶剂中的溶解度和溶剂化数的研究——盐-甲醇-非电解质体系

本文测定了 KClO_3,NaNO_3,NaNO_2三种盐在甲醇-苯,甲醇-甲苯,甲醇-环己烷,甲醇-四氯化碳和甲醇-二氧六环以及 KCl 在甲醇-苯和甲醇-甲苯中的溶解度.它们与非电解质的摩尔分数x_(ne)的关系符合经验公式 log(S_0/S_m)=kX_(ne),其中 S_0和 S_m 分别为盐在纯甲醇和混合溶剂中的溶解度.同时,还得到了经验关系式 log(S_0/S_m)=k_φφ_(ne),其中φ_(ne)为第二组分的体积分数,k_φ称为第二介质常数.盐的溶剂化数近似地符合公式n_++n_-=(2log(S_0/S_m))/(logφ_p)计算得到各种盐的甲醇化数:KClO_3为7.1,NaNO_3为6.4,NaNO_2为5.8.从单纯溶剂化模型出发,应用改进的 Born 公式,推导出第二介质参数 k′的理论计算公式.计算的 k′和实验的 k_φ数值相近,k′对 k_φ有一定的预示.     

定标粒子理论在离子溶剂化自由能计算中的应用

本文根据定标粒子溶液理论计算了KCl、KBr、NaCl、NaBr、CsCl和CsBr在DMSO、DMF、MeOH、(CH₃)₂CO、MeCN、EtOH和H₂O中的溶剂化自由能,涉及的离子-溶剂间静电相互作用能,用“一层连续介质模型”所给出的公式计算,结果与实验符合很好。     

环境中高氯酸盐的自然来源、形成机制及其归趋行为

高氯酸盐(ClO₄^-)作为新型的环境有毒污染物,其环境污染问题已引起国内外学者的极大关注,但有关ClO₄^-的自然来源及形成机制的研究则刚刚起步。ClO₄^-的自然来源、在不同环境介质中的背景浓度及迁移转化行为,对制定ClO₄^-的环境质量标准和系列安全浓度限值至关重要,但国内相关研究几乎为空白。本文总结了ClO₄^-在对流层和平流层气溶胶、大气湿沉降(雨和雪)、地下水、海水、土壤及矿物等环境介质中的背景浓度水平,不同环境介质中涉及样品数为气溶胶3个、雨水1 600多个、降雪样品3个、地下水2 100多个、海水2个、土壤(矿物)10多个、火星土壤样品1个;重点评述了自然源ClO₄^-的前体物质及大气反应形成机制(臭氧氧化、光化学反应和闪电作用),提出ClO₂^-/ ClO₂是大气中ClO₄^-自然形成的关键前体物质;归纳了自然源ClO₄^-在各环境介质间的迁移转化及归趋行为,最后简单介绍了识别ClO₄^-自然来源的同位素示踪技术,并展望相关研究。     

铜配合物中游离水分子对光吸收和吸附Cr（Ⅵ）性能的影响

Cu(ClO₄)₂·6H₂O和(1-甲基-1H-苯并咪唑-2-基)甲醇(HL)在甲醇和乙腈混合溶液中反应生成了深蓝色的[Cu(HL)₃](ClO₄)₂·H₂O (1)和浅蓝色的[Cu(HL)₃](ClO₄)₂(2)。利用元素分析、IR、热重和单晶X射线衍射对它们的结构进行表征分析。测试结果表明配合物1和2均由[Cu(HL)₃]²⁺和抗衡阴离子ClO₄^-组成,只是1中多了一个游离水分子。配合物1和2中的Cu(Ⅱ)均是与来自配体的N原子和O原子配位,配位数为6。热重分析结果表明,配合物1和2均能在30～245℃范围内结构保持不变。但是,深蓝色的配合物1比浅蓝色的配合物2在289 nm处有着更宽的吸收峰;吸附实验表明配合物1在pH=4～8条件下吸附Cr(Ⅵ)的性能优于配合物2。可见配合物1...     

KCl在甲醇-非电解质的混合溶剂中溶解度和溶剂化

本文测定了5、15、25和35 ℃时KCl在甲醇-苯、甲醇-甲苯、甲醇-环己烷和甲醇-四氯化碳中的溶解度S, 并得到经验公式: logS=a+bT, 其中T为绝对温度。同时计算了KCl由甲醇到甲醇混合溶剂的标准迁移自由能ΔG_(tr)~°-, 并得到它和组成x_(Ne)的经验关系式; ΔG_(tr)~°-=CX_(Ne)。同时指出在本实验范围内,温度的变化不影响单纯溶剂化模型和第二介质常数公式的适用性。     

NMR 法研究Na+在二元混合溶剂中的溶剂化

本文测定了NaClO_4在水-丙酮, 水-乙腈,水-乙醇以及NaBPh_4在甲醇-DMF, 甲醇-苯, 甲醇-二氧六圜混合溶剂体系中~(23)Na~+的化学位移随溶剂组成的变化规律。利用等溶剂化点比较了各溶剂对Na~+的溶剂化能力: H_2O>(CH_3)_2CO≥CH_3CN≥C_2H_5OH; DMF>CH_3OH。对于甲醇-DMF和水-丙酮体系, 估算出DMF对甲醇, 丙酮对水的Na~+优先溶剂化自由能分别为-2.7 kJmol~(-1)和+4.6 kJmol~(-1)。在甲醇-苯混合溶剂体系中, ~(23)Na~+的化学位移独立于苯的含量。它支持了甲醇-惰性溶剂混合体系的单一溶剂化模型。而在甲醇-二氧六圜体系中~(23)Na~+的化学位移随混合溶剂组成而发生变化。~(23)Na~+磁共振的峰宽随二氧六圜的加入急剧增加, 这表明二氧六圜分子可能进入了在甲醇中的Na~+原溶剂化层, 导致了Na~+化学环境不对称。     

非金属氧化-还原对MO2/MO2-(M=N,S,Cl)的电子转移反应动力学

以Marcus-Hush电子转移理论为基础,提出了用量子化学密度泛函方法研究自交换和异交换电子转移反应的理论方案.在DFTB3LYP/6-311+G(2D)水平上研究了溶液中NO₂/NO₂^-,SO₂/SO₂^-和ClO₂/ClO₂^-等3个氧化-还原对的自交换以及它们之间的6个交叉电子转移反应的动力学性质,获得了与实验较为一致的结果.     

过渡金属杂硼烷结构规则的量子化学计算

用EHMO量子化学计算方法,计算了过渡金属杂硼烷骨架Fe_{nB6-n(n=0,1,…,6),验证和讨论了过渡金属杂硼烷的价成键和价非键轨道数BMO+NBMO=4n1+9n2-F。其中n1、n2和F都只与骨架的几何性质有关。}     

VIS spectroscopy studies of pseudooctahedral solvation complexes of cobalt(II) ion in mixed solvents

Solvation of cobalt(II) ion in mixed solvents (acetonitrile (AN)-dimethylsulfoxide (DMSO), AN-methanol (MeOH), AN---H₂O, MeOH---H₂O, DMSO---H₂O) has been studied by VIS absorption spectroscopy. A new application of the partial least-squares (PLS) method for the quantitative analysis of the spectral data has allowed to determine the number of solvation complexes and the solvent compositions of their maximum concentration in the solutions investigated. The results have been discussed in respect of the ability of the mixed solvents to solvate preferentially Co(II) ion.     

A STUDY OF THE REDOX CHARACTERISTICS OF THE TERNARY CLATHRATE COMPOUND Mo[S2CN(C2H5)2]4}+{FeCl4}-C6H5CH2SSCH2C6H5

The redox characteristics of the ternary clathrate compound {Mo[S₂CN(C₂H₅)₂]₄}⁺{C₆H₅CH₂SSCH₂C₆H₅}^-was studied by electrochemical measurement and quantum-chemical calculations.The cyclic voltammogram of this ternary clathrate compound in 0.1M KClO₄-DMF with a platinum electride had 2.pairs of redox peak.Both the electrochemical parameters derived from the voltammogram and the results of EHMO calculations indicate that the pair of redox peak at relatively positive potentials corresponds to the redox reaction of Fe(Ⅲ)/Fe(Ⅱ) which is irreversible in nature,while the pair of redox peak at more negative potentials corresponds to the redox reaction of Mo(Ⅴ)/ Mo(Ⅱ) which is semi-reversible.The calculations from experiment measurements are fairly agreement with the theoretical calculations.     

Nd3+离子在数种无机溶剂体系中的化学形式及其激光性质

本工作制备出了Nd³⁺离子的低粘度无机液体激光溶液,研究了溶液的激光性质。用测学⁴F_3/2能级寿命和激光能量输出的方法探讨了Nd³⁺在所述溶剂体系中溶解反应机理和Nd³⁺的化学形式及其结构。     

Effect of solvent on the subnanosecond decay of the second excited singlet state of tetramethylindanethione

The S₂ → S₀ fluorescence spectra and quantum yields and the S₂ lifetimes of 2,2,3,3-tetramethylindanethione (TMIT) have been measured in several solvents using a synchronously pumped picosecond dye laser excitation system. The S₂ nonradiative decay rate is markedly solvent dependent. In inert perfluoroalkane solvents remarkably large S₂-S₀ fluorescence quantum yields (θ_f = 0.14) and long S₂ lifetimes (τ = 880 ps) are measured. Hydrocarbons are efficient excited-state quenchers.     

Role of homogeneous solvents on photophysics of 3-pyrazolyl-2-pyrazoline derivative

S₀ → S₁ and S₀ → S₂ electronic transitions have been observed in UV–Visible absorption spectroscopy of 3-pyrazolyl-2-pyrazoline (PZ) in different homogeneous solvents. Radiative emissions and relaxation processes from S₁ and S₂ states of PZ have been resolved in water, ethylene glycol and glycerol whereas in polar aprotic and protic solvents the radiative transitions have been observed from S₁ state. The S₂–S₁ electronic energy spacing has been calculated from the absorption maxima of the S₀ → S₂ transitions and fluorescence maxima of the S₁ → S₀ transitions. Solute–solvent interactions have been established to rationalize the photophysical modification of PZ in H-bonding solvents.     

双核钼(Ⅴ)二乙基二硫代氨基甲酸络合物的歧化离解平衡及其离解常数

由于发生歧化离解,Mo₂O₃(S₂CNEt₂)₄的溶液不遵守Beer定律,我们测定了有关溶液的光吸收性质以及Mo₂O₃(S₂CNEt₂)₄的歧化离解常数,于15℃时数值为2.2×10^-4。     

Use of a solvatochromic probe for study of solvation in ternary solvent mixture

Solvation characteristics of 2,6-diphenyl-4-(2,4,6-triphenyl-1-pyridino)phenolate in completely miscible ternary solvent mixtures (viz., methanol + acetone + water, methanol + acetone + benzene, and methanol + chloroform + benzene) have been studied by using an electronic spectroscopic procedure. The transition energy (E) corresponding to the charge-transfer band maximum of the solute in a ternary solvent mixture differs significantly from the average E-values in the component solvents weighted by the mole fraction of the solvents. A two-phase model of solvation has been invoked to explain the results. The excess or deficit of solvent components in the local region of the solute molecule over that in the bulk has been estimated using the knowledge of solvation in binary solvent mixtures.     

Mo-Fe-S三元包合物氧化还原特性的研究

本文结合电化学测量和量子化学计算对Mo-Fe-S三元包合物的氧化还原特性进行了研究。用铂电极测得的该包合物在0.1MKClO₄-DMF溶液中的循环伏安图显现出两对氧化-还原峰,由此得到的电化学参数与EHMO计算结果都表明,电位较正的一对峰相应于Fe(Ⅲ)/Fe(Ⅱ)的氧化还原,反应不可逆。电位较负的一对峰相应于Mo(Ⅴ)/Mo(Ⅳ)的氧化还原反应半可逆。     

NMR法研究Na+在二元混合溶剂中的溶剂化

~(23)Na~+ chemical shift of NaClO_4 in mixed solvents of water-aceton,water-ace- tonitrile, and water-ethanol and of NaBPh_4 in methanol-DMF,methanol-ben- zene, and methanol-dioxane were measured.By means of iso-solvation point the solvating abilities were compared as water>aceton≥acetonitrile≥ethanol and DMF>methanol. The preferential solvation free energies of Na~+ for the pairs of solvents, methanol-DMFand water-aceton,were evaluated as -2.7 kJ mol~(-1) for DMF to methanol and 4.6 kJ mol~(-1) for aceton to water.~(23)Na~+ chemical shift in methanol-benzene is independent of the content of benzene. It verifies the simple solvation modle for ion in methanol-inert solvent mixture. However the chemical shift of ~(23)Na~+ in methanol-dioxane mixture varies with the composition of solvent. The inewidth of Na-23 resonance peak increases dramtically with the increasing of dioxane. It seems that the dioxane molecules disturb the primary solvation shell of Na~+ in methanol and result a unsymmetrical immediate surrounding for Na~+ cation.