【作者】 杨阳；

【导师】 高恩庆；

【作者基本信息】 华东师范大学 ， 无机化学， 2014， 硕士

【摘要】 金属有机骨架材料(metal-organic frameworks,简称MOFs)是由无机金属离子和有机配体通过配位键形成的一类新型多孔材料,其在气体吸附/分离、多相催化等方面具有广阔的应用前景。本课题主要研究具有催化性能的Zr(Ⅳ)-MOF系列,该系列材料分为两种：一种是由Zr4+和对苯二甲酸(H2BDC)通过配位键形成的稳定的UiO-66,其金属Zr4+上的配位水分子可通过高温活化去除,金属离子配位环境由原来的八配位变为七配位,形成了Lewis酸位,具有潜在的Lewis酸催化性质,为此我们选择硅腈化反应进行验证。另一种是由Zr4+和2-氨基对苯二甲酸(H2BDC-NH2)通过配位键形成的稳定的Ui0-66-NH2,该材料不仅具有Lewis酸催化性质,又因为在配体上引入了碱性氨基官能团,所以还具有Lewis碱的催化性质,为此我们选择Knoevenagel缩合反应进行验证。1.UiO-66对硅腈化反应的催化性能研究我们在该部分研究内容中主要有以下三点发现：(ⅰ).UiO-66-A不仅是一个能够被循环使用的多相催化剂而且还对反应底物表现出孔道尺寸选择性。(ⅱ).未经过高温处理的UiO-66-H也具有催化活性,通过实验发现,在合成UiO-66过程中使用的调节剂]HAc是UiO-66-H具有活性的主要原因(HAc自身不具有催化活性)。通过探针反应证明了UiO-66-A(Lewis酸)和UiO-66-H(Br(?)nsted酸)的催化活性差异是源自于酸性不同。(ⅲ).吡啶在该反应中不但不会使催化剂中毒反而还具有助催化作用(其自身无催化活性)。2.UiO-66-NH2对Knoevenagel缩合反应的催化性能研究我们在该部分研究内容中主要有以下三点发现：(ⅰ).在强极性的溶剂中,该催化剂能够有效催化芳香醛和氰基乙酸乙酯/丙二睛的缩合反应。(ⅱ).该催化剂在反应体系中是一种对反应底物具有孔道尺寸选择性的多相催化剂,并且在重复使用几次后仍能保持很好的结构完整性和催化活性。(ⅲ).该催化剂具有明显的催化活性是源于其有酸碱双功能催化的特性,我们还发现临近氨基的金属Zr(Ⅳ)能够加速形成中间产物醛亚胺,该中间产物可以活化亚甲基底物并与之反应产生目标产物。更多还原

【Abstract】 Metal-organic frameworks (MOFs) is co composed of inorganic metal ions and organic ligands by coordination bond to form a new-type porous material. MOFs have a broad application prospect in gas adsorption/separation and heterogeneous catalysis. This paper mainly studies the catalytic properties of Zr(IV)-MOFs series and it can be divided into two types:A stable three-dimensional mesoporous material was formed by Zr4+and terephthalic acid through coordination bonds. Upon calcination, the cluster becomes [Zr6(μ3-O)6(μ2-COO)12] by releasing two water molecules, and the Zr centers change from eight-to seven-coordinated, generating potential Lewis-acid sites. Therefore, we have verified the catalytic properties in the Cyanosilylation reaction; Another stable three-dimensional mesoporous material is composed of Zr4+and2-amino terephthalic acid, not only can the material has the Lewis acid catalytic properties mentioned above, but also has Lewis base site due to the introduction of the basic amino functional groups. We have verified the catalytic properties in the Knoevenagel condensation reaction.1. Study on catalytic performance of UiO-66in the Cyanosilylation reactionIn this manuscript, the Zr(IV) MOF UiO-66was studied as a catalyst for aldehyde cyanosilylation. The main findings are as follows, i) The anhydrous form of the MOF (UiO-66-A) is a heterogeneous, substrate-si2e selective and recyclable catalyst, ii) Unexpectedly, the hydrous form (UiO-66-H) shows comparable catalytic properties, thus UiO-66can be used with no need of high-temperature activation. With elaborately designed control experiments, we show that acetic acid trapped in the MOF could be responsible for the activity of UiO-66-H, though acetic acid is inactive by itself The different acidity in UiO-66-H (Br(?)nsted) and UiO-66-A (Lewis) was confirmed by probe reactions. ⅲ) Another unexpected finding is that pyridine, which is inactive alone, acts as co-catalyst, rather than poison, to dramatically accelerate the catalytic reaction, owing to acid-base synergy.2. Study on catalytic performance of UiO-66-NH2in Knoevenagel condensation reactionIn this manuscript, an amino-functionalized Zr(Ⅳ)-MOF with2-aminoterephthalate, UiO-66-NH2, was studied as a solid catalyst for Knoevenagel condensation. The main contributions of this work are as follows. ⅰ) The material can efficiently catalyze the condensation reaction of aromatic aldehydes with cyanoacetate or malononitrile in high-polarity solvents under mild conditions. ⅱ) The catalyst was demonstrated to be heterogeneous and size selectivity, characteristic of a porous catalyst, and it can be recycled without losing its framework integrity and catalytic activity. ⅲ) The superior performance of UiO-66-NH2is attributed to the site-isolated acid-base bifunctional character, and in particular, it was proposed that the Zr site in close proximity to the amino group facilitates the formation of aldimine intermediates, which are the active species reacting with methylene compounds.更多还原