Ionothermal Syntheses And Characterizations Of Open-Framework Compounds

Open-framework compounds, typically known as zeolite materials, possessregular porosity, rich chemical composition and abundant structural diversity. Thesematerials have shown unique physical and chemical properties in optics, electronicsand magnetism due to various metal ions in the frameworks, and exhibited greatpotential applications in the fields of adsorption, separation, catalysis, ion exchangeand host-guest assembly. Therefore, the syntheses of open-framework compoundswith rich structures and interesting properties are of important in the field of materialscience.Ionic liquids are a family of non-conventional molten salts comprised variousanions and cations. It can act not only as new kind of solvents for the syntheses ofinorganic open-framework compounds syntheses but also as structure-directingagents （SDA） and/or template precursors. In contrast to the traditional solvents ofwater and alcohols used in the syntheses of inorganic open-framework compounds,ionic liquid is an ideal “designable” solvent because of its unique characters such aslow melting point, low vapor pressure, reusability and rich categories, etc.This thesis focuses on the systematical study of metal-phosphite andgermanosilicate inorganic open-framework compounds prepared by theaforementioned ionothermal method where ionic liquid plays crucial role as solventand/or template in the reaction. Main achievements include the followings:1. Chiral zeotype compound of germanosilicate SU-32（denoted JIS-SU-32） hasbeen prepared using the co-templating ionothermal method. Organic amine of1,5-diamino-2-methylpentane （MPMD） was added in the ionothermal reaction.Characterizations demonstrate that both protonated MPMD ions and cations ofionic liquid （1-ethyl-3-methylimidazolium） co-exist in the compound as structure directing agents. To the best of our knowledge, this is the first chiralgermanosilicate material have prepared in ionic liquids. By high-throughputsynthetic method, we systematically studied the influence of various factors onthe synthesis, such as Si/Ge ratio, temperature, reaction time, type and amount ofionic liquid. Among them, the ratio of Si/Ge and the type of ionic liquid play keyrole of phase selection in the reaction, whereas reaction temperature dominatesthe particle size in crystallization. Hydrofluroic acid is necessary for thepreparation of high thermal stable JIS-SU-32with Si/Ge ratio of3:1. Otherwise,the denser framework of pharmacosiderite with Si/Ge ratio of1/1is obtained.2. A new open-framework manganese phosphite compound （NH₄）₄[Mn₄（HPO₃）₆]（JIS-10） has been prepared using the ionothermal method. JIS-10is the firstcompound with new Mn/P ratio of2/3in the family of manganese phosphites.The Mn-O-Mn dimmers are connected by anions of [HPO₃]^-groups parallel to abplane forming a two dimensional layered framework. The interlayer ammoniumcations connect the layers into three dimensional supramolecular the structurethrough hydrogen bonds. The structure displays antiferromagnetic interaction.Theroretical calculations with the Heisenberg model demonstrate that themagnetic interaction originates from the antiferromagnetic Mn-O-Mn spin-dimer.3. An open-framework iron phosphite Fe₂^ⅡFe^Ⅲ（NH₄）（HPO₃）₄（JIS-11） has beenprepared using ionic liquid as solvent. The ammonium ions in the structureresulted from decomposition of ionic liquid play a role of template and chargebalance. It is rare that there are mixed Fe^Ⅱand Fe^Ⅲions co-existed in the structure.The compound possesses high thermal stability as indicated by powder X-raydiffraction. Magnetic characterizations show that the compound isantiferromagnetic.4. An open-framework iron phosphite Fe₂（HPO₃）₃（JIS-12） has been prepared usingionic liquid as the solvent. There are12-ring channels along the [001] direction inthe structure of Fe₂（HPO₃）₃,and the Fe³⁺ions are in the form of dimmers. Theas-prepared iron phosphite is isostructure of a hydrothermally prepared knowncompound.