Data_Sheet_1_Highly Efficient Bifunctional Amide Functionalized Zn and Cd Metal Organic Frameworks for One-Pot Cascade Deacetalization–Knoevenagel Reactions.docx

A pyridine-based amide functionalized tetracarboxylic acid, 5,5′-(pyridine-2, 6-dicarbonyl)bis(azanediyl)}diisophthalic acid (H4L), was synthesized and its coordination chemistry toward zinc(II) and cadmium(II) ions was studied. The reactions of H4L with Zn(NO3)2.6H2O and Cd(NO3)2.4H2O led to its full or partial deprotonation, respectively, and the formation of the 2D coordination polymers [Zn2(L)(H2O)4]n.4n(H2O) (1) and [Cd3(HL)2(DMF)4]n.4n(DMF) (2) (DMF = N,N'-dimethylformamide), respectively. They were characterized by elemental analysis, FT-IR, photoluminescence, thermogravimetry, and single-crystal and powder X-ray diffraction. In 1, the L4− ligand is planar with every carboxylate anion binding a Zn(II) cation and giving rise to a 2D grid with the metals with tetrahedral environments. In 2, the combination of bridging HL3− and dimethylformamide to form trinuclear Cd(II) clusters engenders secondary building block units and generates a layer-type 2D network with the metals with octahedral and pentagonal bipyramid coordination geometries. The topological analyses of 1 and 2 reveal 2,4-connected and 3,6-connected binodal nets, respectively. On account of the presence of Lewis acid (Zn or Cd centers) as well as basic (uncoordinated pyridine and amide groups) sites, 1 and (to a much lower extent) 2 effectively catalyze the one-pot cascade deacetalization-Knoevenagel condensation reactions under quite mild conditions. They act as heterogeneous catalysts, being easy to recover and recycle without losing activity.

本研究合成了一种基于吡啶的酰胺功能化四羧酸——5,5′-(吡啶-2,6-二羰基)双(亚氨基)二间苯二甲酸(H4L)，并探究了其与锌(II)、镉(II)离子的配位化学行为。将H4L分别与六水合硝酸锌(Zn(NO3)2·6H2O)和四水合硝酸镉(Cd(NO3)2·4H2O)进行反应，二者可分别使H4L发生完全脱质子与部分脱质子，并分别生成二维配位聚合物[Zn2(L)(H2O)4]n·4n(H2O)(1)与[Cd3(HL)2(DMF)4]n·4n(DMF)(2)（其中DMF为N,N'-二甲基甲酰胺）。采用元素分析、傅里叶变换红外光谱（Fourier Transform Infrared Spectroscopy, FT-IR）、光致发光光谱、热重分析以及单晶与粉末X射线衍射对两种配合物进行了全面表征。在配合物1中，L4−配体呈平面构型，每个羧酸根阴离子均与一个Zn(II)阳离子配位，进而构筑出金属中心为四面体配位环境的二维网格结构。在配合物2中，桥联HL3−配体与二甲基甲酰胺共同形成三核镉(II)簇作为次级结构单元，进而构筑出层状二维网络结构，其中金属中心分别具有八面体与五角双锥配位几何构型。对配合物1和2的拓扑分析结果显示，二者分别为2,4-连接与3,6-连接的双节点网络。得益于配合物1和2均同时具备路易斯酸性位点（Zn或Cd中心）与碱性位点（未配位的吡啶基与酰胺基团），二者可在温和条件下有效催化一锅法级联脱缩醛-Knoevenagel缩合反应，其中配合物1的催化活性更为突出，而配合物2的催化活性相对较弱。二者均为非均相催化剂，易于回收且可循环使用而不丧失催化活性。