Inorganic materials synthesis in ionic liquids

Chapter 25 - Frontier of Inorganic Synthesis and Preparative Chemistry (II)-Designed Synthesis—Inorganic Crystalline Porous Materials

Recent progress in the synthesis of inorganic particulate materials using microfluidics

Conventional synthesis of inorganic materials relies heavily on water and organic solvents. Alternatively, the synthesis of inorganic materials using, or in the presence of, ionic liquids represents a burgeoning direction in materials chemistry. Use of ionic liquids in solvent extraction and organic catalysis has been extensively studied, but their use in inorganic synthesis has just begun. Ionic liquids are a family of non-conventional molten salts that can act as templates and precursors to inorganic materials, as well as solvents. They offer many advantages, such as negligible vapor pressures, wide liquidus ranges, good thermal stability, tunable solubility for both organic and inorganic molecules, and much synthetic flexibility. In this Review, the use of ionic liquids in the preparation of several categories of inorganic and hybrid materials (i.e., metal structures, non-metal elements, silicas, organosilicas, metal oxides, metal chalcogenides, metal salts, open-framework structures, ionic liquid-functionalized materials, and supported ionic liquids) is summarized. The status quo of the research field is assessed, and some future perspectives are furnished.

Metal organic frameworks (MOFs) are a class of porous polymeric material composed of metal ions or clusters linked together by organic bridging ligands. Their large surface areas accompanied by uniform pores, open metal sites, and diverse available post-synthesis functionalization routes make MOFs promising candidate materials for gas storage, separation, and heterogeneous catalysis. MOFs are typically synthesized by solvothermal reactions in organic solvents or in water, but have also been prepared in ionic liquids (ILs) recently; examples of the latter include Cu-BTC (BTC: 1,3,5-benzenetricarboxylate), Ln-BTC, Cd-BTC, Zn-BTC, and others. ILs have been attracting increasing attention as a solvent of choice for chemical synthesis, because of their unique integration of various properties such as essentially zero vapor pressure, excellent solvating properties, easy recyclability, and high thermal stability. The majority of the reports dealing with MOF synthesis have focused on ILs derived from 1-alkyl-3-methylimidazolium. However, deep eutectic solvents (DESs), mixtures of two or more compounds that have melting points lower than that of either of their constituents, are known to exhibit solvent properties very similar to those of ILs and have been employed for MOF synthesis. They have advantages over other types of ILs such as ease of preparation as pure phases from easily available components, low prices, and relative unreactivity towards atmospheric moisture. DES can act as both a solvent and a ligand during the MOF synthesis. MOFs can be synthesized by sonochemical method which has exhibited rapid synthesis kinetics, uniform particle morphology, and excellent phase purity in inorganic materials synthesis. The sonochemical method promotes homogeneous nucleation and reduces crystallization time considerably via the creation, growth, and collapse of an acoustic cavity, generating extremely high temperature (5000-25000 K)/pressure as well as fast heating and cooling rates. In the sonochemical synthesis route, in connection with this reaction mechanism, DESs are thought to create cavitation easily at relatively high temperatures due to their low vapor pressures, and thus have good potential as a reaction medium in the sonochemical synthesis of nanomaterials. In this work, we have chosen the widely investigated Cu3(BTC)2 as a representative MOF material for sonochemical synthesis using choline chloride/dimethylurea DES as a solvent (designated as S-CuBTC). To the best of our knowledge, this is the first report of sonochemical synthesis of a MOF structure in a DES. Effects of various synthesis parameters on the crystallization process of Cu3(BTC)2 were examined, and the properties of the sample were compared to those of Cu3(BTC)2 prepared via a conventional ionothermal synthesis route in an oven (designated as C-CuBTC). In order to use MOFs for adsorption, rigorous guest removal from the pores has to be performed so as to achieve the highest possible surface area (and pore volume). This is typically accomplished by solvent washing and vacuum treatment. Since the mixture of choline chloride and 1,3dimethylurea in a molar ratio of 1:2 used in this work has a eutectic temperature of around 70 C, removal of the solvent guest before it solidifies inside the pores is challenging. Thus, an effective activation procedure for Cu3(BTC)2 samples obtained under ionothermal synthesis conditions was briefly examined by conducting repeated sample washing with de-ionized water and ethanol in the manner described in entries I to V in Table 1. No apparent PXRD patterns or morphology changes were observed after washing step II (see Figure S1 and S2). The corresponding SEM images after different washing steps did not reveal any noticeable differences either, except that the DES coated at the external surface in the Cu3(BTC)2 sample was removed. However, repeated washing (200 mL × 2) by de-ionized water and ethanol was necessary to obtain the BET surface area of a high quality Cu3(BTC)2, as shown in Table 1. Elemental analysis of the C-CuBTC sample after washing treatment IV confirmed the virtual elimination of DES; The

The development of novel functional materials has attracted widespread attention to meet the constantly growing demand for addressing the major global challenges facing humanity, among which experimental synthesis emerges as one of the crucial challenges. Understanding the synthesis processes and predicting the outcomes of synthesis experiments are essential for increasing the success rate of experiments. With the advancements in computational power and the emergence of machine learning (ML) techniques, computational guidelines and data-driven methods have significantly contributed to accelerating and optimizing material synthesis. Herein, a review of the latest progress on the computation-guided and ML-assisted inorganic material synthesis is presented. First, common synthesis methods for inorganic materials are introduced, followed by a discussion of physical models based on thermodynamics and kinetics, which are relevant to the synthesis feasibility of inorganic materials. Second, data acquisition, commonly utilized material descriptors, and ML techniques in ML-assisted inorganic material synthesis are discussed. Third, applications of ML techniques in inorganic material synthesis are presented, which are classified according to different material data sources. Finally, we highlight the crucial challenges and promising opportunities for ML-assisted inorganic materials synthesis. This review aims to provide critical scientific guidance for future advancements in ML-assisted inorganic materials synthesis.

ADVERTISEMENT RETURN TO ISSUEPREVBook and Media Revie...Book and Media ReviewNEXTBook Review of Inorganic Materials Synthesis and FabricationLes PesterfieldCite this: J. Chem. Educ. 2010, 87, 3, 274Publication Date (Web):February 9, 2010Publication History Published online9 February 2010Published inissue 1 March 2010https://pubs.acs.org/doi/10.1021/ed8001072https://doi.org/10.1021/ed8001072book-reviewACS PublicationsCopyright © 2010 The American Chemical Society and Division of Chemical Education, Inc. This publication is available under these Terms of Use. Request reuse permissions This publication is free to access through this site. Learn MoreArticle Views822Altmetric-Citations-LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail PDF (550 KB) Get e-AlertscloseSUBJECTS:Crystal structure,Crystallography,Inorganic compounds,Manufacturing,Nanomaterials Get e-Alerts

A number of papers on the metal nanoparticle synthesis method have been reported to date because metal nanoparticles are expected to be key materials for further development of science and technology.1 Of these, from a practical application standpoint, the accelerated electron beam irradiation method,2 which can be conducted at existing industrial plants for sterilizing medical kits, has been attracting attention. In this decade, several approaches to synthesize metal nanoparticles in ionic liquid (IL) have been proposed by several research groups, too.3 Some scientists point out that IL behaves as an excellent medium for formation and stabilization of the metal nanoparticles. Recently we have succeeded in the metal nanoparticle preparation by the approach with combination of the accelerated electron beam irradiation method and the IL, which is called ionic liquid-accelerated electron beam irradiation (IL-AEBI) method.4However the past ILs used for the method are not green and expensive price. The aim of this study is to design the biocompatible and cost-effective ILs suitable for metal nanoparticle, especially Pt nanoparticle, preparation by the IL-AEBI method. After supporting the resulting Pt nanoparticles onto untreated multi-walled carbon nanotubes (Pt-MWCNTs), oxygen reduction reaction (ORR) electrocatalytic activity of the Pt-MWCNTs was also examined. Biocompatible and cost-effective ILs were prepared by a neutralization method. Carboxylic acids, e.g., propionic acid, hexanoic acid, levulinic acid, were slowly added into a choline bicarbonate aqueous solution to avoid unexpected thermal decomposition of the carboxylic acids by heat of neutralization. The crude IL solutions were purified prior to use. Solutions of 5.0 mM platinum acetylacetonate (Pt(acac)2) in biocompatible ILs were encapsulated in perfluoroalkoxyethylene container in a dry Ar gas-filled glove box with O2 and H2O <1 ppm. Accelerated electron beam irradiation experiments were carried out at an existing common industrial plant for sterilizing medical kits (accelerated energy: 4.8 MeV; beam current: 10 mA; absorbed dose: 6 kGy; irradiation time: ca. 2 sec.). Pt-MWCNTs were prepared by reference to our previous paper.5The resulting Pt nanoparticles supported on MWCNT was rinsed by acetonitrile. Characterization of all the samples prepared in this study was conducted by TEM, EDX, ICP, electrochemical measurements, etc. Solvated electrons and radicals are readily produced in various solvents by quantum beam irradiation including gamma-ray and electron beam. The generated reactive species are directly related to preparation of metal nanoparticles.2 However, as is often the case with ILs, it is hard to produce metal nanoparticles since usual ILs show a better radiation stability than conventional aqueous and organic solvents. Many years ago we revealed that only 1,3-dialkylimidazolium cation-based ILs yield a sufficient number of metal nanoparticles by the IL-AEBI because such ILs can release a limited amount of reactive species.4 It is important to know the radiation stability of biocompatible ILs in light of the application to the IL-AEBI method. NMR measurements for the neat ILs after the accelerated electron beam irradiation suggested the production of the reactive species during the irradiation. In fact, after the accelerated electron beam irradiation to the solutions of 5.0 mM Pt(acac)2 in the biocompatible ILs, existence of monodispersed Pt nanoparticles in the ILs was identified by TEM observation. Mean particle size of the Pt nanoparticle was ca. 2 ~ 3 nm. Possibility of the Pt nanoparticles as the electrocatalysts was investigated after preparing the Pt-MWCNTs.4 Surprisingly the mean particle size remained even after the preparation process at 473 K and the Pt nanoparticles were immobilized onto a basal plane of the MWCNTs. Electrocatalytic activity was examined by typical electrochemical analyses using the Pt-MWCNTs coated on a glassy carbon rotating disk electrode.5 As given in Table I, the characteristics are strongly dependent on the ionic liquid species. Given the variation in the mass activity, it is possible that the d-band center of Pt nanoparticles is influenced by the carboxylate anions. In conclusion, our designed biocompatible and cost-effective ILs are suitable reaction media for metal nanoparticle preparation by the IL-AEBI method. Acknowledgement Part of this research was supported by the Grant-in-Aid for Scientific Research, Grant Numbers 15H03591, 15K13287, and 15H2202 from the Japanese Ministry of Education, Culture, Sports, Science and Technology. References Nanoparticles: From Theory to Application, G. Schmid, ed., Wiley-VCH, Weinheim, 2004. J. Belloni, Cat. Today, 113, 141 (2006). J. Dupont and J. D. Scholten, Chem. Soc. Rev., 39, 1780 (2010). T. Tsuda, S. Seino, and S. Kuwabata, Chem. Commun.,6792 (2009); ibid, 48, 1925 (2012). K. Yoshii, T. Tsuda, T. Arimura, A. Imanishi, T. Torimoto, and S. Kuwabata, RSC Adv., 2, 8262 (2012). Figure 1

Chapter 23 - The Frontier of Inorganic Synthesis and Preparative Chemistry (I)—Biomimetic Synthesis

In recent years ionic liquids have emerged as an important class of compounds for the synthesis of metal nanoparticles. The significant advantage of using ionic liquids is their dual role of reaction solvent and nanoparticle stabilizer. The variability of ionic liquids enables their chemical properties to be tuned by the rational introduction of functional moieties. Metal nanoparticles and ionic liquids appear to be ideal complementary components for the construction of multifunctional catalytic systems. The development of multifunctional systems based on the combination of catalytically active nanoparticles and functionalized ionic liquids allows the integration of complex multi-step catalytic reactions in a one-pot process. The design of efficient metal nanoparticle ? functionalized ionic liquid catalysts is currently attracting much attention. The thesis is centered on the design, synthesis, characterisation and the catalytic applications of novel metal nanoparticle ? ionic liquid based catalytic systems. In the first chapter a general introduction to the field of metal nanoparticles immobilized in ionic liquids is presented, and the recent evolution of metal nanoparticle ? acidic ionic liquid multifunctional catalysts is reviewed. The second chapter covers the studies on chlorometallate ionic liquids. Lewis acidity of various chlorometallate systems was evaluated with respect to the speciation present in these systems. The speciation in chlorozincate ionic liquids was determined by different techniques. The obtained scale of Lewis acidity of the chlorometallate ionic liquids and the understanding of the speciation in these systems allowed accurate selection of the appropriate system for catalytic applications. The third and the fourth chapters describe the studies concerning the ability of the chlorometallate ionic liquids to function in a cooperative manner with rhodium nanoparticles in hydrogenation reactions. A novel bifunctional catalyst, consisting of rhodium nanoparticles dispersed in a Lewis acidic ionic liquid medium, was developed. In the third chapter the rhodium nanoparticle component of the catalyst is characterized. Subsequently, the combined bifunctional catalytic system was used to catalyse the hydrogenation of aromatic compounds and was found to exhibit excellent activity under mild conditions. In the fourth chapter, the high activity of the rhodium nanoparticle ? Lewis acidic ionic liquid catalyst the direct hydrogenation of challenging heteroarene substrates is demonstrated. Chlorozincate(II), chloroaluminate(III) and chlorogallate(III) ionic liquids were found to be effective as a second active component of the catalytic system. The chemoselective reduction of different quinolines, pyridines, benzofurans was performed at mild conditions ? 30 bar and 80-120°C and the corresponding heterocycles were obtained in high yields. The high selectivity of the catalyst and its tolerance to different functional groups was demonstrated on a broad range of substrates. The recyclability of the rhodium nanoparticle ? Lewis acidic ionic liquid catalyst was evaluated. The final chapter presents two reduced graphene oxide supported rhodium nanoparticle catalysts obtained in ionic liquid media via microwave-assisted and conventional thermal heating methods. The rhodium nanoparticle-reduced graphene oxide composites were characterized by different techniques. The catalytic performance of the rhodium nanoparticle-reduced graphene oxide composites was evaluated in the hydrogenation of quinoline compounds under mild conditions, i.e. 10 bar and 80°C. The advantages of the microwave-assisted ionic liquid synthesis for the production of highly efficient catalysts were demonstrated. The long-term stability of the catalyst obtained by microwave-assisted method was studied and the catalyst could be recycled several times without significant loss in activity and selectivity.

Ionic liquids (ILs) can add value to many chemical processes. The electrochemistry and the (physical) organic chemistry communities in particular have extensively studied the structure, properties, and reactivities of various ILs and reactions therein. Inorganic and materials chemists are the newest addition to the IL community: over a number of years, various approaches to the fabrication of inorganic solids with unprecedented and sometimes unique structures and properties have been reported. This article summarizes the state of this particular sub-field of IL research and highlights a few promising approaches that not only reproduce conventional synthesis in ILs, but that provide pathways towards new, possibly unknown, inorganics with advantageous properties that cannot (or only with great difficulty) be made via conventional processes.

Chapter 24 - Frontier of Inorganic Synthesis and Preparative Chemistry (I) Biomimetic Synthesis

Review: 82 refs.

Aiming to develop environmentally compatible chemical syntheses, the replacement of traditional organic solvents with ionic liquids (ILs) has attracted considerable attention. ILs are special molten salts with melting points below 100 degrees C that are typically constituted of organic cations (imidazolium, pyridinium, sulfonium, phosphonium, etc.) and inorganic anions. Due to their ionic nature, they are endowed with high chemical and thermal stability, good solvent properties, and non-measurable vapor pressure. Although the recovery of unaltered ILs and recycling partly compensate their rather high cost, it is important to develop new synthetic approaches to less expensive and environmentally sustainable ILs based on renewable raw materials. In fact, most of these alternative solvents are still prepared starting from fossil feedstocks. Until now, only a limited number of ILs have been prepared from renewable sources. Surprisingly, the most available and inexpensive raw material, i.e., carbohydrates, has been hardly exploited in the synthesis of ILs. In 2003 imidazolium-based ILs were prepared from o-fructose and used as solvents in Mizoroki-Heck and Diels-Alder reactions. Later on, the first chiral ILs derived from sugars were prepared from methyl D-glucopyranoside. In the same year, a family of new chiral ILs, obtained from commercial isosorbide (dianhydro-D-glucitol), was described. A closely related approach was followed by other researchers to synthesize mono- and bis-ammonium ILs from isomannide (dianhydro-D-mannitol). Finally, a few ILs bearing a pentofuranose unit as the chiral moiety were prepared using sugar phosphates as glycosyl donors and 1-methylimidazole as the acceptor.

The development of sustainable advanced materials is increasingly driven by the need for sustainable, faster, scalable, and more efficient research workflows. Advancements in computational screening, high‐throughput experimentation, and artificial intelligence (AI) are accelerating progress in materials discovery. To fully leverage the benefits of these complementary approaches, the implementation of materials acceleration platforms (MAPs) and self‐driving laboratories (SDL) has emerged as a promising strategy. Here, we present the development of a semi‐automated station for the lab‐scale high‐throughput synthesis (HTS) of inorganic materials, as part of the Materials Acceleration and Innovation plaTform for ENergy Applications (MAITENA). The system integrates two in‐house‐designed liquid‐handling modules capable of performing sol‐gel, Pechini, solid‐state, and hydro/solvothermal syntheses. Each module enables the preparation of several dozen gram‐scale samples per week with high reproducibility and minimal manual intervention. The system's capabilities are demonstrated through three case studies involving Li‐ion battery materials. Results highlight the module's utilization for efficient screening of compositions and synthesis conditions to vary materials’ properties. This accessible and modular infrastructure offers a practical route to implementing high‐throughput strategies in inorganic materials research.

Titanium dioxide (TiO2) has received significant attention because of the global climate change and the consumption of fossil fuel resources. Specifically, using TiO2 in photocatalytic applications, such as the removal of organic pollutants and a hydrogen production has become an important issue. Thus, many researchers have attempted to prepare highly active TiO2 materials using various synthetic approaches. Modifications of the conventional sol-gel method, such as the addition of surfactants, have been employed in synthetic procedures. Moreover, hydrothermal, solvothermal, sonochemical and microwave methods have also been used as alternative approaches. Recently, the use of ionic liquids represents a burgeoning direction in inorganic material synthesis. Ionic liquids are exceptional solvents consisting of ions possessing low vapor pressure and tunable solvent properties. This article reviews the preparation of TiO2 materials using ionic liquids with various synthetic approaches. Also, sustainable energy and environmental cleanup applications of TiO2 materials, including the treatment of hazardous organic substances and hydrogen energy derived from electrochemical methods, are discussed.