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Vibrational spectroscopic studies have been carried out on solutions of LiBF4 in acetonitrile as a function of concentrations of lithium salt. Great changes in the vibrational characteristics of C⋮N and C−C stretches were observed as a result of solvation. The solvation numbers of Li+ determined from spectroscopic data are found to decrease from 3.2 to 1.4 with increasing concentration of the lithium salt. It is expected that the solvation number is 4 in the infinite diluted solution. Solvation structures of the lithium ion were suggested by density functional theory and the results were compared with the spectroscopic data. Changes of the ν1 mode of BF4- with concentration of the salt were also analyzed, and the bands at 763, 771, and 780 cm-1 indicate the coexisting of free ion, contact ion pairs, and dimers. The structures of ion pairs in gas phase and in acetonitrile solutions were suggested on the basis of DFT calculations. [ABSTRACT FROM AUTHOR]

A Pickering emulsion is a natural microreactor for interfacial catalysis in which an emulsifier is critical. Recently, a metal-organic framework (MOF) has attracted attention to emulsify water-organic mixtures for constructing a Pickering emulsion. However, a few stimuli-responsive Pickering emulsions based on MOFs have been reported, and the MOF emulsifiers cannot be regenerated at room temperature. Herein, the Zr-MOF with a rodlike morphology is synthesized using ionic liquid as a modulator and then modified with n -(trimethoxysilylpropyl)imidazole (C 3 im) to prepare a series of functionalized Zr-MOFs (MOF-C 3 im). It is found that MOF-C 3 im is an excellent emulsifier to construct stable and CO 2 -responsive Pickering emulsions even at low content (>0.20 wt %). Notably, the emulsification and demulsification of the emulsions can be easily and reversibly switched by bubbling of CO 2 and N 2 alternatively at room temperature because CO 2 and imidazole molecules anchored on the Zr-MOF underwent a reversible acid-base reaction, resulting in an obvious change in the wettability of the emulsifier. As a proof of concept, the reduction reactions of nitrobenzene have been successfully carried out in these Pickering emulsions, demonstrating the efficient integration as a microreactor for chemical reaction, product separation, and emulsifier recycling under ambient conditions. This strategy provides an innovative option to develop stimulus-responsive Pickering emulsions for sustainable chemical processes.

The nonlinear-optical (NLO) materials with second-harmonic-generation (SHG) response need to crystallize in the noncentrosymmetric space group. It is very difficult to control the synthetic conditions to solely form a noncentrosymmetric phase for the materials with noncentrosymmetric and centrosymmetric conformations. Herein, we found that the temperature and halogen anion play an important role during the formation procedure of the pure noncentrosymmetric or centrosymmetric phase for the halogen-based family of coordination polymers to yield hybrid materials with a phase-matching SHG response as well as inherit the primary excellent photonic property of organic linkers. Our results provide a good choice for the design and construction of novel materials with a particular photonic property.

Microviscosity changes of living cells have a far-reaching influence on diffusion and movement capacity of RNA and, more seriously, could modify RNA functions in living cells. Fluorescent rotor, whose fluorescence responds to different environmental viscosities, holds great potential for the imaging of viscosity in biosystem. Although many fluorescent rotors have been reported for viscosity, the fluorogenic rotor with ultrasensitivity for the determination of microviscosity (<10 cP) was rarely reported. Herein, we report a nucleoside-based two-photon fluorescent rotor (dABp-3) that can selectively and ultrasensitively image microviscosity in RNA region of living cells for the first time. 2'-Deoxyadenosine is selected as an electron donor to permit energy transfer via the acetylenic bond to acceptor, a typical boron dipyrromethene moiety. Another highlight, dABp-3 is based on 2'-deoxyadenosine, which result in its recognition capacity for RNA. dABp-3 with ultrasensitivity provides a varied linear response to the microrange viscosity (1.8-6.0 cP) in RNA region of living cells on dual-mode-two-photon ratio mode and fluorescence lifetime mode. After screening and optimization, advantageously, dABp-3 can be used to screen reticulocytes from mature blood cells of thrombosis models in vitro and in vivo because of targeting RNA, while simultaneously image microviscosity changes in these cells. So, dABp-3 as an analytical tool holds considerable promise for bioimaging and monitoring of microviscosity changes in complex biological systems.

Beta-cyclodextrin (beta-CD) is difficult to dissolve in water and in many common solvents and searching for the proper solvents is the key step to expand its application. In this work, six kinds of hydrophilic ionic liquids 1-n-butyl-3-methylimidazolium chloride, 1-(2-hydroxyethyl)-3-methylimidazolium chloride, 1-allyl-3-methylimidazolium chloride, 1-n-butyl-3-methylimidazolium dicyanamide, 1-(2-hydroxyethyl)-3- methylimidazolium dicyanamide and 1-allyl-3-methyl-imidazolium dicyanamide have been prepared. The solubilities of beta-cyclodextrin in these ionic liquids have been determined in the temperature range from 333.2 to 363.2 K with 5 K intervals. The solution thermodynamic parameters of beta-cyclodextrin have been calculated from the solubility data. It was shown that solubility of beta-cyclodextrin was remarkable in ionic liquids, it was as high as 125.0 g in 100 g of [Amim][N(CN)(2)] at 348.2 K. The dissolution process was unfavorable thermodynamically and controlled by the enthalpic term. (1)H NMR and IR spectroscopic measurements were used to study the enhanced dissolution of beta-cyclodextrin in the ionic liquids. The results indicated that 1:1 inclusion complexes were formed between beta-cyclodextrin and imidazolium cations of the ionic liquids. The differences in the solubility of beta-cyclodextrin have been discussed from the interionic interaction between cation and anion of the ionic liquids and the inclusion interaction of the cations of the ionic liquids into the cavities of beta-cyclodextrin. The strength of the interionic interactions was found to be predominant for the dissolution of beta-cyclodextrin. It is expected that such information may find application in the molecular design of the stationary phases in gas chromatography.

The formation of ionic liquids aggregates in aqueous solution is of great importance to the future applications of ionic liquids. In this work, aggregation behavior of 1-alkyl-3-methylimidazolium salts [C8mim]X (X = Cl, Br, [NO3], [CH3COO], [CF3COO], [CF3SO3], and [ClO4]), 1-octyl-4-methylpyridinium bromide (4m-[C8pyr]Br), and 1-methyl-1-octylpyrrolidinium ([C8mpyrr]Br) has been investigated in aqueous solutions by conductivity, volume, fluorescence, dynamic light scattering, and transmission electron microscopy. The critical aggregation concentration (CAC), ionization degree of the aggregates alpha, the standard Gibbs energy of aggregation deltaG(m)degrees, the average aggregation number N, the apparent molar volumes at critical aggregation concentration V(phi,CAC), the apparent molar volumes in aggregation phase V(phi)mic, and the change of the apparent molar volumes upon aggregation deltaV(phi,m), have been derived from the experimental data for these ionic liquids. It is found that both nature of the anions and ring type of the cations significantly affect the aggregation in aqueous solution. The anionic effect basically follows the Hofmeister series, and the ability of anionic hydration is predominant for the aggregation behavior of the ionic liquids. Hydrophobicity and steric hindrance of the cations as well as binding strength of the cations with the anions are suggested to play important roles in the aggregation of [C8mim]Br, 4m-[C8pyr]Br, and [C8mpyrr]Br. The investigated ILs were found to form spherical aggregates. Structures of anions and cations have very weak effects on the morphology, but they do affect the aggregate sizes.