Imidazolium-based ionic liquids grafted on solid surfaces

Abstract

Supported ionic liquids (SILs), which refer to ionic liquids (ILs) immobilized on supports, are among the most important derivatives of ILs. The immobilization process of ILs can transfer their desired properties to substrates. Combination of the advantages of ILs with those of support materials will derive novel performances while retaining properties of both moieties. SILs have been widely applied in almost all of fields involving ILs, and have brought about drastic expansion of the ionic liquid area. As green media in organic catalytic reactions, based on utilizing the ability of ILs to stabilize the catalysts, they have many advantages over free ILs, including avoiding the leaching of ILs, reducing their amount, and improving the recoverability and reusability of both themselves and catalysts. This has critical significance from both environmental and economical points of view. As novel functional materials in surface science and material chemistry, SILs are ideal surface modifying agents. They can modify and improve the properties of solids, such as wettability, lubricating property, separation efficiency and electrochemical response. With the achievements in the field of ILs, using magnetic nanoparticles (MNPs) to SILs has drawn increasing attention in catalytic reactions and separation technologies, and achieved substantial progress. The combination of MNPs and ILs renders magnetic SILs, which exhibit the unique properties of ILs as well as facile separation by an external magnetic field. In this article, we focus on imidazolium-based ILs covalently grafted to non-porous and porous inorganic materials. The excellent stability and durability of this kind of SILs offer a great advantage compared with free ILs and IL films physically adsorbed on substrates without covalent bonds. Including examples from our own research, we overview mainly the applications and achievements of covalent-linked SILs in catalytic reactions, surface modification, separation technologies and electrochemistry.

Highly Efficient and Convenient Supported Ionic Liquid TiCl5-DMIL@SiO2@Fe3O4-Catalyzed Cycloaddition of CO2 and Epoxides to Cyclic Carbonates

“…Figure 5 showed the diffuse reflectance UV-Vis spectra of the supported ILs. All the supported ILs exhibit a peak around 215 nm, which are assigned to the O-Si transition [38,41]. In addition to this peak, another peaks appeared at around 413, 492, 556 nm in Fig.…”

“…Immobilized ILs have the attractive features of ILs and heterogeneous catalysis, such as easy catalyst recovery, high efficiency, high stability and recyclability. Thus, this problem can be overcome by immobilizing the traditional IL on solid supports [38][39][40][41][42][43][44][45][46]. Various methods have been developed for immobilization of ILs on solid supports such as alumina, titania, silica, etc, and among these solid supports, silica was found to be one of the most effective one [41].…”

“…Thus, this problem can be overcome by immobilizing the traditional IL on solid supports [38][39][40][41][42][43][44][45][46]. Various methods have been developed for immobilization of ILs on solid supports such as alumina, titania, silica, etc, and among these solid supports, silica was found to be one of the most effective one [41]. In the present study, a series of silica coated magnetic nanoparticles supported functionalized ionic liquids anion-DMIL@SiO 2 @Fe 3 O 4 have been prepared and characterized, which exhibited good chemical and thermal stability, and were applied as a novel heterogeneous catalyst in the preparation of cyclic carbonates by cycloaddition of CO 2 to epoxides (Scheme 1).…”

Advances in Organic and Organic-Inorganic Hybrid Polymeric Supports for Catalytic Applications

“…In 2014, a series of multilayered covalently-supported ionic liquid phase (mlc-SILP) materials 18, 19a-b, 20a-b, 21a-b were synthesised by grafting different bis-vinylimidazolium salts on thiolfunctionalised silica (Scheme 9) [17]. Covalently-supported imidazolium salts represent an interesting class of recyclable catalysts with excellent stability and durability [18,19]. Bis-imidazolium salts with different organic linkers (ethane, butane, octane, p-xylene) between the two imidazolium units and two types of halides as counterions (X = Br or I) were used.…”

1,3-Disulfonic acid benzimidazolium chloride as an efficient and recyclable ionic liquid catalyst for the synthesis of 3,4-dihydropyrimidine-2-(1H)-ones/thiones

“…In this regard, ionic liquids have attracted significant research interest in the context of green synthesis due to their adjustable physical and chemical properties [3]. They have been introduced as an alternative green reaction medium given their exceptional features including high thermal and chemical stability, low vapor pressure, nonflammability, non-volatile nature, large electrochemical window, potential recyclability, and the ability to dissolve many organic and inorganic materials [4][5][6]. These compounds have been used extensively in electrochemistry, spectroscopy, and extraction and separation processes [7].…”