分子动力学模拟研究[Bmim][PF6]+水+醇三元体系的微观结构和分子间相互作用

研究离子液体体系的微观结构和分子间相互作用具有重要意义. 本文对1-丁基-3-甲基咪唑六氟磷酸盐([Bmim][PF₆])+水+乙醇和[Bmim][PF₆]+水+异丙醇三元体系进行了分子模拟研究, 计算了径向分布函数和不同组成的水-醇混合溶剂与离子液体阴阳离子间的相互作用能, 并将其分解为库仑相互作用能和Lennard-Jones(LJ)势能. 在此基础上, 研究了溶液体系的微观结构、分子间相互作用和相行为. 结果表明, 水倾向于与离子液体阴离子和阳离子极性部分作用, 醇倾向于与阴离子和阳离子非极性部分作用; 库仑力主导阴离子-溶剂相互作用, 色散力主导阳离子-溶剂相互作用, 阴阳离子的缔合状态对色散力影响较小, 对库仑力的影响非常显著.     

分子模拟研究气体在室温离子液体中的溶解度

在作者先前建立的分子力场基础上, 采用Widom粒子插入法预测了CO₂、N₂、O₂、Ar及CH₄等5种气体在多种咪唑类离子液体中的溶解度, 包括2种侧链长度的阳离子和3种阴离子. 首先考察了256个离子对组成的体系中溶质分子插入次数对计算结果的影响, 在此基础上计算了不同温度下气体在1-丁基-3-甲基咪唑的四氟化硼盐([bmim][BF₄])和六氟化磷盐([bmim][PF₆])中的溶解度. 计算结果正确反映了CO₂气体溶解度的变化趋势, 在[bmim][BF₄]中溶解度的模拟结果与实验值符合很好, 且明显优于Pádua等的模拟结果；在[bmim][PF₆]中的溶解度较实验值偏高, 精度与文献模拟结果相当；并预测了较高温度下CO₂气体在[bmim][BF₄]和[bmim][PF₆]中的溶解度. 计算结果也正确地反映了5种气体在[bmim][PF₆]中溶解度实验值的相对大小. 另外考察了常温下几种气体在不同室温离子液体中的溶解度, 模拟结果表明气体在含有较长碳链和双-三氟甲基磺酰胺阴离子(Tf₂N^－)的离子液体中溶解度较大.     

离子液体[bmim][BF4]对联苯甲酰光化学反应影响的瞬态吸收光谱

利用纳秒级激光光解瞬态吸收光谱研究了联苯甲酰(BZ)在离子液体1-丁基-3-甲基咪唑四氟硼酸盐([bmim][BF₄])与乙腈(MeCN)混合体系中的光化学反应行为. 考察了探针分子BZ存在下[bmim][BF₄]/MeCN比例对体系中化学反应动力学的影响. 实验发现: 在N₂饱和条件下, BZ溶液经激光辐照后产生的激发三线态³BZ^*遵循一级反应动力学规律衰减. 离子液体(IL)相对比例增加对³BZ^*瞬态吸收峰的位置和强度没有产生明显影响. 但离子液体体积分数V_IL的变化对[bmim][BF₄]/MeCN混合溶剂中光诱导电子转移的影响却非常显著, 总体上电子转移产生的自由基的表观生成速率常数k_gr随[bmim][BF₄]的V_IL增大而减小. 在[bmim]BF₄]比例足够大的情况下, ³BZ^*与三乙胺或四甲基对苯二胺之间的电子转移被抑制.     

离子液体促进四氟硼酸铜催化芳醛和乙酸酐合成1,1-二乙酸酯

在室温条件下, 离子液体1-正丁基-3-甲基六氟磷酸盐([bmim]PF₆)能促进四氟硼酸铜催化一系列芳醛和乙酸酐反应, 以83%～97%的产率生成相应的1,1-二乙酸酯. 在离子液体[bmim]PF₆存在情况下, 催化剂活性远远高于无离子液体存在下的活性. 催化剂用量仅需 0.2 mol%就能使反应顺利进行, 远远少于文献报道的其它催化剂的用量, 反应在3～20 min内完成. 实验结果表明该法催化剂用量少、产率高、反应时间短、离子液体可重复使用、对环境友好.     

离子液体[EMIM][PF6]负载纳米SiOx表面的熔点及结构

制备了离子液体(1-乙基-3-甲基咪唑六氟磷酸 [EMIM][PF₆])负载量不同的多孔纳米氧化硅(SiO_x), 并采用差式扫描量热分析(DSC)、X射线衍射(XRD)、激光Raman光谱、傅里叶变换红外(FTIR)光谱分析等手段研究离子液体负载纳米氧化硅后的熔点变化及相行为. 研究表明负载于纳米氧化硅表面的离子液体熔点明显下降, 且负载于不同表面羟基含量的氧化硅表面熔点下降幅度不同. 纯离子液体[EMIM][PF₆]熔点为62 ℃, 在纳米氧化硅表面负载量为35%时熔点为52 ℃, 比负载前下降10 ℃; 负载于另两种不同羟基含量的纳米氧化硅表面后熔点分别下降20和17 ℃. 而同一种纳米氧化硅(比表面积为640 m²·g^-1)在负载量小于50%时, 熔点下降明显; 进一步增大负载量, 熔点逐渐趋于本体. XRD和Raman光谱分析显示, 离子液体负载于氧化硅表面后其衍射峰或吸收峰相对强度发生明显改变. 分析负载前后纳米氧化硅的结构变化, 推断离子液体熔点下降的主要原因是离子液体分子与纳米氧化硅表面之间存在强烈的界面相互作用, 而表面羟基的密度及比表面积是影响负载后[EMIM][PF₆]离子液体相行为的主要因素.     

联吡啶[3,2-a：2’,3-c]-7-氮杂-吩嗪铜(I)配合物的合成、表征及其与DNA的相互作用

合成了邻菲罗啉衍生物联吡啶[3,2-a:2',3'-c]-7-氮杂-吩嗪(dpapz)及其铜(I)配合物[Cu(dpapz)₂]PF₆, 利用核磁共振氢谱(¹H NMR), 傅里叶变换红外(FTIR)光谱, 高分辨质谱(HR ESI-MS)等对合成的化合物进行了表征.采用紫外-可见吸收光谱,荧光光谱, DNA熔解温度实验和循环伏安方法研究了dpapz和[Cu(dpapz)₂]PF₆与小牛胸腺DNA(CT DNA)的相互作用. 配体dpapz与小牛胸腺DNA(CT DNA)作用时未观察到吸收峰红移并且减色效应较小(<30%), 且DNA熔解温度也上升较小(ΔT_m=7.8 ℃), 说明dpapz以沟槽结合的方式与CT DNA相互作用. 而[Cu(dpapz)₂]PF₆与CT DNA作用时, 可观测到较小的吸收峰红移(2-3 nm)和较大的减色效应(>50%), 同时DNA熔解温度上升较大(ΔT_m=11.1 ℃), 表明[Cu(dpapz)₂]PF₆以静电相互作用和部分扦插的方式与DNA结合. 溴乙锭(EB)荧光竞争实验和循环伏安实验进一步证实了这一结论. 配体dpapz和[Cu(dpapz)₂]PF₆与DNA的结合常数分别为2.88×10⁵和5.32×10⁵ mol·L^-1. 光照条件下, [Cu(dpapz)₂]PF₆产生单重态氧的能力与dpapz相当, 但产生超氧负离子自由基的能力要弱于dpapz. 活性氧猝灭实验表明, 超氧负离子自由基、单重态氧和羟基自由基均参与了dpapz和[Cu(dpapz)₂]PF₆对DNA的光损伤作用. [Cu(dpapz)₂]PF₆对DNA的亲和性要高于对dpapz的, 使得[Cu(dpapz)₂]PF₆对质粒DNA的光损伤效率明显强于dpapz.     

离子液体-分子溶剂混合体系中电导率的测量与关联

在298.15K下测定了1-正丁基-3-甲基咪唑四氟硼酸盐([Bmim][BF₄])和1-正丁基-3-甲基咪唑六氟磷酸盐([Bmim][PF₆])与不同分子溶剂混合体系的电导率。结果表明, 随着分子溶剂浓度的增大，离子液体的摩尔电导率逐渐增大，离子液体在溶液中的摩尔电导率可以用纯离子液体的摩尔电导率、分子溶剂的介电常数和摩尔体积进行关联。     

系列含4，5-二氮杂-9，9’-螺二芴配体的钌配合物的合成及其性能研究

本文合成了3个新钌（Ⅱ）配合物,[Ru（bpy）₂（SB）]（PF₆）₂、[Ru（bpy）（SB）₂]（PF₆）₂和[Ru（SB）₃]（PF₆）₂（bpy=2,2’-bipyridine,SB=4,5-diaza-9,9’-spirobifluorene）,通过核磁和元素分析对配合物的结构进行了确定。[Ru（bpy）₂（SB）]（PF₆）₂通过X射线单晶衍射确认了结构。研究了配合物的光物理性能。结果表明[Ru（bpy）₂（SB）]（PF₆）₂在乙腈中的发桔红光,波长为606nm,量子产率约为0.0012。在同样条件下[Ru（bpy）（SB）₂]（PF₆）₂和[Ru（SB）₃]（PF₆）₂的发光非常微弱甚至几乎没有发光。还研究了这些配合物的电致化学发光性能。随着配体中SB含量的增加,发光的峰电压从1.36V增加到1.58V,相对发光强度从731降低到52。     

分子动力学模拟研究[Bmim][PF_6]+水+醇三元体系的微观结构和分子间相互作用(英文)

研究离子液体体系的微观结构和分子间相互作用具有重要意义.本文对1-丁基-3-甲基咪唑六氟磷酸盐([Bmim][PF6])+水+乙醇和[Bmim][PF6]+水+异丙醇三元体系进行了分子模拟研究,计算了径向分布函数和不同组成的水-醇混合溶剂与离子液体阴阳离子间的相互作用能,并将其分解为库仑相互作用能和Lennard-Jones(LJ)势能.在此基础上,研究了溶液体系的微观结构、分子间相互作用和相行为.结果表明,水倾向于与离子液体阴离子和阳离子极性部分作用,醇倾向于与阴离子和阳离子非极性部分作用;库仑力主导阴离子-溶剂相互作用,色散力主导阳离子-溶剂相互作用,阴阳离子的缔合状态对色散力影响较小,对库仑力的影响非常显著.     

CMPO/[Cnmim][NTf2]体系对Eu3+和UO22+的萃取行为

讨论了辛基(苯基)-N,N-二异丁基胺甲酰基甲基氧化膦(CMPO)/1-烷基-3-甲基咪唑双(三氟甲烷磺酰)亚胺盐([C_nmim][NTf₂],n=2,8,12)萃取体系分别对硝酸溶液中的铕离子(Eu³⁺)和铀酰根离子(UO₂²⁺)的萃取行为。主要研究了硝酸浓度、接触时间、温度、CMPO浓度对CMPO/[C_nmim][NTf₂]体系萃取性能的影响,并选取CMPO/[C2mim][NTf₂]体系对模拟高放废液中的镧锕元素进行了萃取分离。结果表明:随着离子液体侧链长度增长,萃取平衡时间逐渐延长;CMPO/[C2mim][NTf₂]体系对Eu³⁺的萃取是放热反应,萃取率随酸度增加而逐渐降低,对UO₂²⁺则是吸热反应,萃取率随酸度增加而逐渐升高;通过机理研究,推测出对Eu³⁺的萃取反应是离子交换,而对UO₂²⁺的萃取反应则是中性配位;CMPO/[C2mim][NTf₂]体系能有效的萃取模拟高放废液中的镧系、锕系元素,且在高酸下有一定的镧锕分离效果。     

Role of the Surfactant Structure in the Behavior of Hydrophobic Ionic Liquids within Aqueous Micellar Solutions

The behavior of an ionic liquid (IL) within aqueous micellar solutions is governed by its unique property to act as both an electrolyte and a cosolvent. The influence of the surfactant structure on the properties of aqueous micellar solutions of zwitterionic SB‐12, nonionic Brij‐35 and TX‐100, and anionic sodium dodecyl sulfate (SDS) in the presence of the “hydrophobic” IL 1‐butyl‐3‐methylimidazolium hexafluorophosphate ([bmim][PF₆]) is assessed along with the possibility of forming oil‐in‐water microemulsions in which the IL acts as the “oil” phase. The solubility of [bmim][PF₆] within aqueous micellar solutions increases with increasing surfactant concentration. In contrast to anionic SDS, the zwitterionic and nonionic surfactant solutions solubilize more [bmim][PF₆] at higher concentrations and the average aggregate size remains almost unchanged. The formation of IL‐in‐water microemulsions when the concentration of [bmim][PF₆] is above its aqueous solubility is suggested for nonionic Brij‐35 and TX‐100 aqueous surfactant solutions.     

Synthesis of Carbonyl Compounds from Alcohols Using Electrochemically Generated Superoxide Ions in RTILs

Abstract

We show that the superoxide ion (O₂ ^??) generated electrochemically from oxygen dissolved in room-temperature ionic liquids (RTILs) reacts with primary and secondary alcohols to form the corresponding ketones and carboxylic acids, respectively. Specifically, we study the conversion of benzhydrol to benzophenone and benzyl alcohol to benzaldehyde/benzoic acid. The kinetics (e.g., rate, selectivity, and yield) for these reactions are also determined as functions of the variations in the structure of the ionic liquids. The RTILs used here are imidazolium-based cations where the functional groups on the imidazolium ring are modified. Specifically, 1-butyl-3-methylimidazolium hexafluorophosphate [bmim][PF₆], 1-butyl-2,3-dimethylimidazolium hexafluorophosphate [bdmim][PF₆], and 1-hexyl-3-methylimidazolium hexafluorophosphate [hmim][PF₆] are used as the reaction medium. These results are compared to an ammonium-based RTIL (N-butyl-N-trimethylammonium bis(trifluoromethylsulfonyl)imide). The results show that the nucleophilic attack by the O₂ ^?? of both the RTIL and the alcohol, especially that of the H atom at the R2 position of the [bmim][PF₆] and [hmim][PF₆], greatly affects the yields. No RTIL degradation products were detected for the reactions in [bdmim][PF₆] and N-butyl-N-trimethylammonium bis(trifluoromethylsulfonyl)imide ionic liquids. For the benzyl alcohol oxidation reaction in the RTIL, N-butyl-N-trimethylammonium bis(trifluoromethylsulfonyl)imide, benzaldehyde formed did not undergo further oxidation to form benzoic acid, which may be due to the greater hydrophobicity of this RTIL. The competitive reaction kinetics between the alcohol and RTIL component must be considered in the selection of the RTIL solvent system.     

Solvent relaxation of a room-temperature ionic liquid [bmim][PF6] confined in a ternary microemulsion

In this paper we have reported the solvent and rotational relaxation of 1-butyl-3-methyl-imidazolium hexafluorophosphate ([bmim][PF₆]) confined in tween 20/([bmim][PF₆]/water microemulsion using coumarin 153 (C-153) as probe. The most interesting feature of our experiment was that we observed an increase in solvent relaxation time with increase in R (R = tween 20-to-[bmim][PF₆] molar ratio). This is due to the fact that with increase in [bmim][PF₆] content of the microemulsions, the microviscosity of the pool of the microemulsions increases, and motion of ions of [bmim][PF₆] is hindered in the pool of microemulsions. Since motion of ions is responsible for solvation in room-temperature ionic liquids (RTILs), solvent-relaxation time increases with increase in R.     

Baylis-Hillman reaction in [bdmim][PF6] ionic liquid

A new use of ionic liquid [bdmim][PF₆] as solvent for the Baylis-Hillman reaction is presented. Unlike the commonly used [bmim][PF₆] that evidently reacts with electrophilic aldehydes under basic conditions, ionic liquid [bdmim][PF₆] is inert and the Baylis-Hillman reaction in [bdmim][PF₆] proceeds smoothly with better yield.     

Enzymatic polyester synthesis in ionic liquids

The enzymatic synthesis of polyesters by ring-opening polymerization (ROP) and polycondensation in three ionic liquids, i.e., [bmim][Tf₂N], [bmim][PF₆] and [bmim][BF₄] was investigated. For the enzymatic ROP of ε-caprolactone it was found that [bmim][PF₆] and [bmim][BF₄] result in an inhomogeneous reaction mixture upon polymerization, causing polymerization characteristics similar to bulk polymerization. In contrast, for [bmim][Tf₂N] characteristics similar to toluene were observed. Molecular weights of 7000-9500 g/mol were obtained. In the polycondensation of dimethyl adipate and dimethyl sebacate, respectively, with 1,4-butanol the low volatility of ionic liquids was successfully utilized to perform the reactions in an open vessel at temperatures close to the boiling point of the condensation by-product. Molecular weights up to 5400 g/mol were obtained. This, in combination with the tunable solvent hydrophilicity of ionic liquids could offer an advantage in the polymerization of highly polar monomers with low solubility in organic solvents.     

离子液体型表面活性剂研究

以1-甲基咪唑为原料, 制备了6个常规离子液体: 1-正丁基-3-甲基咪唑四氟硼酸盐及六氟磷酸盐(简称[bmim][BF₄]及[bmim][PF₆])、1-正己基-3-甲基咪唑四氟硼酸盐及六氟磷酸盐(简称[hmim][BF₄]及[hmim][PF₆])、1-正十六烷基-3-甲基咪唑四氟硼酸盐及六氟磷酸盐(简称[C₁₆mim][BF₄]及[C₁₆mim][PF₆])和4个功能化离子液体: 1-(2-羟乙基)-3-甲基咪唑四氟硼酸盐及六氟磷酸盐(简称[2-hemim][BF₄]及[2-hemim][PF₆])、1-乙氧羰基甲基-3-甲基咪唑四氟硼酸盐及六氟磷酸盐(简称[eocmmim][BF₄]及[eocmmim][PF₆]). 研究了这两类离子液体的一些物理性能, 旨在挖掘离子液体在香料香精化妆品工业中的应用价值. 分别检测了它们与一般溶剂的互溶性, 并测定了它们的表面张力和发泡性能, 实验结果表明, 仅[C₁₆mim][BF₄]和[C₁₆mim][PF₆]具有发泡性能, 发泡力分别为68和120 mm.     

1-Butyl-2,3-trimethyleneimidazolium bis(trifluoromethylsulfonyl)imide ([b-3C-im][NTf2]): a new, stable ionic liquid

Using imidazole as the starting material, the synthesis of a new bicyclic ionic liquid [b-3C-im][NTf₂] is described. Except for the alkylation reaction in the second step (40% yield) of this four-step synthesis of [b-3C-im][NTf₂], others were all high yielding reactions (85-94% isolated yields). We investigated intrinsic reactivity of this and other imidazolium-based ionic liquids and found that, under strongly basic conditions (KOD in CD₃OD/D₂O (1:1) solution), the new ionic liquid was stable to solvent deuterium isotope exchange while the previously reported [bdmim][NTf₂] and [bdmim][PF₆] ionic liquids were 50% deuterium exchanged at its C-2 methyl in 30 min at ambient temperature. At the same experimental condition, the most commonly employed [bmim][PF₆] ionic liquid was deuterium exchanged instantaneously at its C-2 hydrogen. In the absence of bases (CD₃OD/D₂O = 1:1), only [bmim][PF₆] was deuterium exchanged (50% within 1 h) and other ionic liquids gave no detectable exchanges even after one week at ambient temperature. It is therefore concluded that the new [b-3C-im][NTf₂] ionic liquid is far more chemically stable than previously reported [bmim][PF₆], [bdmim][NTf₂], and [bdmim][PF₆].     

Micropolarity and aggregation behavior in ionic liquid + organic solvent solutions

UV–vis spectroscopy and conductivity measurement techniques were used to study the physicochemical and structural properties of the binary or ternary mixtures of 1-n-butyl-3-methylimidazolium hexafluorophosphate ([bmim][PF₆]) + organic solvent and 1-n-butyl-3-methylimidazolium tetrafluoroborate ([bmim][BF₄]) + organic solvent systems. The solvents involved were acetonitrile, water, ethanol, ethyl acetate, and tetrahydrofuran. It was indicated that the micropolarity and the aggregation behavior of the mixtures depend strongly on the dielectric constants of the solvents and the composition of the mixtures.