基于变压红外光谱研究离子液体[MPIM][I]与石墨烯氧化物之间的相互作用

本研究利用红外光谱研究不同压力下离子液体1-Methy1-3-propylimidazolium iodide([MPIM][I])与石墨烯及其氧化物的相互作用.结果表明,[MPIM][I]对压力的变化具有高敏感度,咪唑环与烷基链在0.4 GPa时产生相变化,可明显观察到吸收峰的裂解,且连续加压会导致咪唑环与烷基链的振动频率蓝移.[MPIM][I]与石墨烯作用时加压至2.5 GPa也未观测到相变化的产生,且咪唑环与烷基链的振动频率蓝移趋势也不明显;[MPIM][I]与石墨烯氧化物作用时咪唑环与烷基链的结果与添加石墨烯时几乎相同.石墨烯氧化物具有羟基、羧基、环氧基等共价键结在其表面,这些羟基会扰动[MPIM][I]中的咪唑环与烷基链,导致在常压下振动频率发生蓝移,进而表明石墨烯表面的官能基团会与离子液体产生相互作用.     

离子液体增塑二醋酸纤维素的红外及二维相关红外光谱研究

以离子液体1-丁基-3-甲基咪唑六氟磷酸盐(BMIMPF_6)为增塑剂,采用傅里叶变换红外光谱(FTIR)和二维相关光谱分析技术,研究BMIMPF_6增塑二醋酸纤维素(CDA)体系在室温(25℃)以及升温过程(35～210℃)中CDA与离子液体的相互作用,为离子液体增塑CDA熔融加工提供理论指导。结果表明,温度25℃时,增塑体系中CDA形成氢键的羟基、乙酰基基团、 BMIMPF_6中阴离子以及咪唑环上C—H相较于未增塑前均出现特征峰位置偏移或强度变弱的情况,且随着增塑剂含量增加,变化程度加剧,证实离子液体与CDA发生了相互作用,这种相互作用存在于离子液体咪唑环上活泼氢与CDA乙酰基、咪唑环上活泼氢与CDA骨架C—O以及阴离子与CDA乙酰基之间,有助于破坏和削弱CDA中原有氢键网络结构。在升温过程中,未增塑CDA形成氢键的羟基吸收峰呈现强度变小、高频偏移的规律,并一直存续于整个升温过程,乙酰基基团相应特征峰维持稳定的状态,而增塑后CDA中羟基吸收峰变化程度较之于增塑前明显加剧,且温度高于180℃后羟基完全消失,乙酰基中C=O, C—O以及骨架上C—O对应吸收峰变形、强度大幅度减小,说明增塑后CDA热稳定性下降,对热的抵抗力更弱。进一步对增塑CDA在35～170℃之间的二维红外相关技术分析表明,升温过程中增塑CDA体系经历离子液体咪唑环上孤立活泼氢和CDA中自由羰基先发生相互作用,随后离子液体阴阳离子解除相互作用, CDA中原本缔结氢键的乙酰基相应基团因氢键受热被破坏而释放出自由羰基、酯基C—O和甲基,并与离子液体阴阳离子形成了相互作用的过程,此后CDA骨架上的C—O也参与到与离子液体的相互作用中。CDA乙酰基与BMIMPF_6阴阳离子相互作用比CDA原有氢键作用结合力和离子液体阴阳离子之间的相互作用更强,并随着温度升高进一步加强。     

离子液体存在下银的电沉积及其表面增强拉曼散射活性研究

离子液体作为一种绿色介质,在电化学领域的应用研究正在兴起,并已引起了研究者的浓厚兴趣.运用循环伏安法研究了离子液体(1-丁基-3-甲基咪唑硝酸盐,[bmim]NO3)添加剂存在时,AgNO3溶液中的Ag在玻碳电极上的电化学沉积行为.研究表明,离子液体的加入对Ag的沉积具有阻化作用.采用扫描电镜(SEM)对沉积层的表面形貌进行表征,结果显示离子液体的存在可使沉积层更加致密,Ag颗粒的尺寸减小.以甲基橙为探针分子,研究了在加入及不加[bmim]NO3添加剂的AgNO3溶液中电沉积所得银颗粒膜的表面增强拉曼散射(SERS)效应,增强因子分别为1.7×105和1.1×105,表明在离子液体存在下制得的Ag颗粒膜具有相对较好的SERS活性.     

离子液体[bmim][PF6]与乙腈混合体系中的激光光解研究

以蒽醌(AQ)作为探针分子,利用激光光解技术研究了咪唑型离子液体1-丁基-3-甲基咪唑六氟化磷([bmim][PF6])与乙腈(MeCN)混合体系中的光化学反应行为.研究结果表明,离子液体[bmim][PF6]自身可与激发三线态的蒽醌分子(3AQ*)进行反应,且表观反应速率常数随着[bmim][PF6]/MeCN比例的不同呈现特殊规律性的变化.在离子液体的摩尔分数(xRTIL)为0.06处观察到一个明显的临界点.当xRTIL＜0.06时,表观速率常数随xRTIL的增大而增大;而当xRTIL＞0.06时,表观速率常数随xRTIL的增大而减小.文章给出了[bmim][PF6]/MeCN混合体系中激光诱导化学反应的动力学常数,并初步推测了其反应机理,进一步揭示了离子液体[bmim][PF6]的一些新的光化学特性.     

离子液体双水相体系-紫外分光光度法测定恶喹酸

建立了由亲水性离子液体溴化1-乙基-3-丁基咪唑[Emim]Br和K2HPO4形成的双水相体系对恶喹酸的紫外分光光度测定方法。优化了[Emim]Br和K2HPO4成相的条件,研究了萃取恶喹酸的最佳体系。采用混合液体（pH=7.0磷酸盐缓冲液,15%三氯醋酸水溶液）提取样品,离子液体双水相体系的富集。回收率为97.6%—98.7%,相对标准偏差为2.4%—15.3%。该检测猪恶喹酸残留具有干扰小、速度快、灵敏度高等优点。     

液体离子提取烟梗木质素的研究（英文）

本文研究了在温和的条件下利用四种离子液体对烟梗木质素的提取过程,结果表明1-乙基-3-甲基咪唑磷酸二乙酯盐([EMIM][DEP])的提取效果最佳.通过80℃的热水搅拌30 min的预处理过程可以有效脱除烟梗中含有的绝大多数糖分同时疏松了烟梗的微纤维结构,在此基础上使用[EMIM][DEP]在150℃和反应时间4 h的条件下可以获得纯度90.21%的木质素,木质素的提取率达到85.38%.     

室温离子液体中超声制备纳米氧化锌掺杂材料及机理研究

在室温离子液体1-丁基-3-甲基咪唑四氟硼酸盐(ImBF_4)中超声制备镧系离子掺杂的纳米氧化锌材料,采用X射线衍射、透射电镜、光声光谱和荧光光谱技术表征样品结构和发光性能。为研究反应机理,采用甲基自由基复合法对离子液体的空化温度进行间接实测,进一步与空化动力学的数值分析结果进行比较。实验结果表明镧系离子掺杂可以有效地调控氧化锌的发光。与传统溶剂不同,离子液体空化温度不随超声时间的延长而降低,并随环境温度升高略有上升。反应机理的研究表明样品的形成生长与超声辐照和离子液体的共同作用密不可分。     

液体离子提取烟梗木质素的研究

本文研究了在温和的条件下利用四种离子液体对烟梗木质素的提取过程，结果表明1-乙基-3-甲基咪唑磷酸二乙酯盐([EMIM][DEP])的提取效果最佳. 通过80 °C的热水搅拌30 min的预处理过程可以有效脱除烟梗中含有的绝大多数糖分同时疏松了烟梗的微纤维结构，在此基础上使用[EMIM][DEP]在150 °C和反应时间4 h的条件下可以获得纯度90.21%的木质素，木质素的提取率达到85.38%.     

室温离子液体中超声辐照制备氧化锌纳米棒的研究

离子液体与超声技术结合在纳米材料的制备中具有广阔的前景,但目前以离子液体为溶剂超声制备纳米材料的报道还不多见,相关的反应机理研究也亟待开展.本文首次在室温离子液体1-丁基-3-甲基咪唑四氟硼酸盐中超声制备了氧化锌纳米棒,该方法具有简便、快速和环境友好等特点.采用X射线衍射(XRD)、透射电子显微镜(TEM)对纳米氧化锌的结构和形貌进行表征.作为比较研究,采用传统的低蒸汽压有机溶剂二缩三乙二醇在同样的超声反应条件制备了纳米氧化锌材料.离子液体中超声合成样品为直径约20 nm,长度30-50 nm的纳米棒,而在二缩三乙二醇中超声制备的样品为直径6～8 nm的纳米颗粒.利用光声光谱(PAS)研究了纳米氧化锌样品的光学性能和量子尺寸效应.对离子液体中超声制备氧化锌纳米棒可能的反应机理进行了讨论并建立了的反应模型.结果表明在在超声辐照和离子液体溶剂的共同作用下氧化锌纳米棒得以生成.     

2,2''-联咪唑类离子液体配位的双核铜配合物的合成、光谱表征及晶体结构研究

以2,2'-联咪唑为原料制得离子液体1,3,1'-三丁基-2,2'-联咪唑六氟磷酸盐,将此离子液体与醋酸铜配位得到了1,3,1'-三丁基-2.2'-联咪唑六氟磷酸盐配位的双核铜配合物.采用元素分析,IR,UV,ESI对其结构进行了表征.并用X-ray单晶衍射仪确定了其单晶结构,化合物属三斜晶系,空间群P-1晶胞参数α=0.84507(11)nm,b=1.11663(15)nm,c=1.6262(2)nm.α=96.640(2)°β=11.860(3)°,γ=98.091(3)°;V=1.4760(3)nm3,Dc=1.418g/cm3,Z=1,F(000)=654,μ=0.865mm-1.     

Molecular dynamics study of confined ionic liquids in Au nanopore

Molecular dynamics simulations were carried to investigate the structure and dynamics of [BMIM][PF₆] ionic liquid (IL) confined inside a slit-like Au metal nanopore with a pore size of 5.0 nm. The calculations show that the mass and number densities of the confined ILs are oscillatory; the solid-like high density layers are formed in the vicinity of the metal surface. The orientational investigation shows that the imidazolium ring of [BMIM] cations prefers to form a small tilt angle with the pore walls. Furthermore, the mean squared displacement (MSD) calculation indicates that the dynamics of confined ILs are remarkably slower than those observed in bulk systems. Our results suggest that the confinement of the Au nanopore can strongly affect the structural and dynamical properties of the confined ILs.     

Influence of ultrasound-assisted ionic liquid pretreatments on the functional properties of soy protein hydrolysates

In this work, the effect of dual-frequency ultrasound-assisted ionic liquids (ILs) pretreatment on the functional properties of soy protein isolate (SPI) hydrolysates was investigated. The degree of hydrolysis (DH) of SPI pretreated by ultrasound and [BMIM][PF₆] increased by 12.53% as compared to control (P < 0.05). More peptides with low molecular weight were obtained, providing support for the changes in DH. The trichloroacetic acid-nitrogen soluble index presented an increase, suggesting a better protein hydrolysate property. The increase in the calcium-binding activity showed the ultrasound-assisted ILs pretreatment could potentially improve bone health. The foaming capacity and stability of SPI hydrolysates pretreated by ultrasound-assisted [BMIM][PF₆] always increased remarkably as compared to ultrasound-assisted [BDMIM][Cl] pretreatment. However, the synergistic effect of ultrasound-assisted [BMIM][PF₆] on the emulsifying activity and antioxidant activities (DPPH and hydroxyl radical scavenging activity) was not as ideal as ultrasound-assisted [BDMIM][Cl] pretreatment, which may be affected by the structure of peptide. In conclusion, these results indicated the combination of dual-frequency ultrasound and ionic liquids would be a promising method to improve the functional properties of SPI hydrolysates and broaden the application scope of compound modification in proteolysis industry.     

离子液体[BMIM][BF_4]水溶液比热容及热工特性分析

离子液体在化工和能源领域应用研究中,其比热及热工特性尤为重要,然而目前相关的比热数据较缺乏.研究主要对离子液体[BMIM][BF4]及其水溶液的比热容进行了测定.测试系统采用耐驰DSC204HP低温高压差热仪,测试精度较高且稳定可靠.实验测试的温度范围为273.15K~423.15K,测试的离子液体摩尔浓度分别为1.0...     

Changes in dynamical behavior of ionic liquid in silica nano-pores

Dielectric relaxation measurement has been carried out on an ionic liquid (1-butyl-3-methyl imidazolium hexafluorophosphate, [BMIM][PF₆]) confined in nano-porous silica matrix. Two dielectric relaxation peaks have been observed in the confined ionic liquid (IL) while there is only one relaxation peak for bulk IL. Confinement results in layering of some IL molecules near the pore wall while other molecules, less affected by pore wall interaction, remain in the central core. The two relaxation peaks are assigned to the different dynamical behaviors of the central core and layered IL molecules.     

Investigation of cation–anion interaction in 1‐(2‐hydroxyethyl)‐3‐methylimidazolium‐based ion pairs by density functional theory calculations and experiments

Gas‐phase structure, hydrogen bonding, and cation–anion interactions of a series of 1‐(2‐hydroxyethyl)‐3‐methylimidazolium ([HOEMIm]⁺)‐based ionic liquids (hereafter called hydroxyl ILs) with different anions (X = [NTf₂]^–, [PF₆]^–, [ClO₄]^–, [BF₄]^–, [DCA]^–, [NO₃]^–, [AC]^– and [Cl]^–), as well as 1‐ethyl‐3‐methylimizolium ([EMIm]⁺)‐based ionic liquids (hereafter called nonhydroxyl ILs), were investigated by density functional theory calculations and experiments. Electrostatic potential surfaces and optimized structures of isolated ions, and ion pairs of all ILs have been obtained through calculations at the Becke, three‐parameter, Lee–Yang–Parr/6‐31 + G(d,p) level and their hydrogen bonding behavior was further studied by the polarity and Kamlet–Taft Parameters, and ¹H‐NMR analysis. In [EMIm]⁺‐based nonhydroxyl ILs, hydrogen bonding preferred to be formed between anions and C2–H on the imidazolium ring, while in [HOEMIm]⁺‐based hydroxyl ILs, it was replaced by a much stronger one that preferably formed between anions and OH. The O–H···X hydrogen bonding is much more anion‐dependent than the C2–H···X, and it is weakened when the anion is changed from [AC]^– to [NTf₂]^–. The different interaction between [HOEMIm]⁺ and variable anion involving O–H···X hydrogen bonding resulted in significant effect on their bulk phase properties such as ¹H‐NMR shift, polarity and hydrogen‐bond donor ability (acidity, α). Copyright © 2011 John Wiley & Sons, Ltd.     

芘在离子液体及常规溶剂中的激光闪光光解研究

利用纳秒级时间分辨激光光解装置,以Nd:YAG激光器三倍频后的355 nm激光作为激发光源,研究了芘在常规溶剂乙腈、丙酮、环己烷、1-丁基-3-甲基咪唑六氟磷酸离子液体([Bmim][PF6])、N-丁基吡啶四氟硼酸离子液体([BuPy][BF4])以及三乙基庚基铵双三氟甲磺酰亚胺(R4NNTf2)的瞬态光解行为,比较...     

Revisited vibrational assignments of imidazolium‐based ionic liquids

Imidazolium‐based ionic liquids (ILs) involving anions of variable coordinating strength have been investigated using infrared (IR) and Raman spectroscopies, density functional theory (DFT) calculations and selective deuteration of the imidazolium CH groups. Particular emphasis has been placed on the vibrational assignments of the anion and cation internal vibrations, a prerequisite before any interpretation of spectral changes due to ion–ion interactions in these unconventional liquids. The vibrations of highly symmetric and weakly coordinating anions, such as PF₆⁻, have unperturbed wavenumbers, but unexpected IR or Raman activity for some modes, showing that the anion is subjected to an anisotropic electric field. The stretching as well as the in‐plane and out‐of‐plane bending modes of the imidazolium CH groups are anharmonic. They give broad bands that reflect a large distribution of interactions with the surrounding anions. All the bending modes are mixed with ring vibrations and the stretching modes are complicated by Fermi resonance interactions with overtones and combination of in‐plane ring modes. However, the stretching vibration of the quasi‐diatomic C₍₂₎ D bond appears to be a good spectroscopic probe of the increasing cation–anion interactions when the coordinating strength of the anion increases. The broad absorption observed in the far IR with weakly coordinating anions remains practically unchanged when the acidic C₍₂₎ H imidazolium bond is methylated and even when the imidazolium cation is substituted by tetra‐alkyl ammonium or pyrrolidinium cations. It is concluded that this absorption is a general feature of any IL, coming from the relative translational and librational motions of the ions without needing to invoke C₍₂₎ H anion hydrogen bonds. Copyright © 2010 John Wiley & Sons, Ltd.     

Multiscale modelling strategies and experimental insights for the solvation of cellulose and hemicellulose in ionic liquids

ABSTRACT

The present study investigates the dissolution behaviour of cellulose and hemicellulose in potential ionic liquids (ILs) using both the quantum chemical and experimental validation. For converging upon the recommended IL, 1428 ILs consisting of 42 cations and 34 anions were studied with the conductor like screening model for real solvents (COSMO-RS) model. Based on the infinite dilution activity coefficient of the components in IL, the selected anions and cations were visualised by observing their interactions with cellulose and hemicellulose using interaction energies, natural bonding orbital analysis and molecular dynamics simulations. The dissolution order of cellulose and hemicellulose in ILs was primarily determined by the evaluation of hydrogen bonds between the oxygen atom of anion and hydroxyl proton of cellulose/hemicellulose. From this discernible fact, the anion of the IL was observed to play a leading role in the solvation process as compared to the cation. Eventually, acetate [OAc]^– anion and 1-ethyl-3-methylimidazolium [EMIM]⁺ cation were found to be good candidates for the dissolution of cellulose and hemicellulose. This was further confirmed by the measurement of solid-liquid equilibria with cellulose and hemicellulose. The regenerated cellulose powder was then characterised by Fourier transform spectroscopy(FTIR), X-ray diffraction (XRD) and Thermal gravimetric analysis (TGA).     

离子液体热分解机理的原位变温多核核磁共振研究

利用原位变温核磁共振氢谱(~1H NMR)、核磁共振氟谱(~(19)F NMR)和核磁共振磷谱(~(31)P NMR)等NMR技术研究特定温度下离子液体的热分解机理.在温度低至80℃时,1-丁基-3-甲基咪唑阳离子(C4mim~+)和六氟磷酸根阴离子(PF6~—)组成的离子液体[C4mim][PF_6]呈现1个缓慢但明显的分解过程.无水[C_4mim][PF_6]在温度高于80℃时开始分解,生成少量的五氟化磷(PF_5)和氟化氢(HF),氟化氢中的氢原子来自于1-丁基-3-甲基咪唑环2位上的氢原子.在丢掉这个氢原子后,阳离子成环形成一个卡宾,并与PF5形成卡宾/PF5复合物.定量NMR分析显示在分解反应达到平衡状态时,自由态PF5和卡宾/PF5复合物的比例为7∶3.     

Effects of Room Temperature Ionic Liquids on Fluorescence Characteristics of 17β-estradiol and its Derivative

Previous reports have seldom concerned about the RTILs (Room temperature ionic liquids), and their effects on derivatization reaction or derivatives. In this study, we reported that the effects of four different RTILs, i.e., [EMIM]PF₆, [BMIM]PF₆, [HMIM]PF₆ and [OMIM]PF₆, on fluorescence spectra of 17 β-estradiol (E2), and its derivatization solvent dansyl chloride (DNSCl) and the derivative. [BMIM]PF₆ had a significant quenching effect on the fluorescence intensity of E2, suggesting the formation of [BMIM]PF₆/E2 complexes and possible buried E2 molecular in a more hydrophobic microenvironment. The estimated Stern-Volmer quenching constant (Ksv = 0.3519) proved that E2 quenching caused by [BMIM]PF₆ was a dynamic quenching process. Four RTILs, with different alkyl chain-length in imidazolium cation, resulted in different quenching intensities to E2 as follows: [EMIM]PF₆ > [BMIM]PF₆ > [HMIM]PF₆ > [OMIM]PF₆. At 5 mg L⁻¹ of DNSCl, [BMIM]PF₆, [HMIM]PF₆ and [OMIM]PF₆ increased the fluorescence intensities of E2 in water by 8.5, 7.6 and 6.1 times, respectively, and a 37-nm hypsochromic shift occurred. The fluorescence intensity for [BMIM]PF₆-extracted derivative of E2 increased more than two times compared with that for the control. In conclusion, this study demonstrated that above four hexafluorophosphate salt ionic liquids could be used in derivatization reaction to enhance fluorescent sensitivity in E2 trace residual analysis.