1,3,5-三(苯咪唑-1-基甲基)-2,4,6-三甲基苯配子與過渡性金屬離子自組裝合成、結構與性質探討

Abstract

本論文主旨為研究1,3,5-tris(benzimidazoyl-1-ylmethyl)-2,4,6 -trimethylbenzene (TBzIm)含羧酸根有機配子與過渡性金屬離子(CoII, ZnII, MnII, NiII)進行水熱自組裝反應，製備金屬-有機配位聚合物(metal–organic coordination polymers)。 本論文共合成八種配位聚合物，分別為4(H3O)+[Zn8(TBzIm)2(btc)4Cl8]•4H2O (1)、[Zn12(TBzIm)2(bdc)4Cl16]•3H2O (2)、[Co4(TBzIm)4(Hbtc)4] (3)、[Co2(TBzIm)2(bdc)2]•3H2O (4)、[Mn5Cl10(TBzIm)4]•1acetone (5)、[Co2(Fum)2(TBzIm)2]n (6) 、[Ni2(Fum)2(TBzIm)2]n (7)和[Co12(TBzIm)4(D-Cam)12] (8)。論文分成三部分探討，第一部分 (化合物1-4) 為經由柔性TBzIm搭配二價鋅金屬離子(ZnII) 或二價鈷金屬離子(CoII)，並混合剛性均苯三甲酸(trimesic acid, H3Btc)、對苯二甲酸(terephthalic acid, H2Bdc)之含羧酸根有機配子進行水熱自組裝反應，形成二維或三維的金屬-有機配位聚合物；第二部分(化合物5)為經由TBzIm與二價錳金屬離子(MnII)進行水熱自組裝反應，形成三維金屬-有機配位子結構，該化合物顯現特殊之磁性行為；第三部分 (化合物6-8) 為經由TBzIm搭配二價鈷金屬離子(CoII)或二價鎳金屬離子(NiII)，混合天冬胺酸(aspartic acid, Asp)、酒石酸(tartaric acid, Tar)、樟腦酸(camphanic acid, D-cam)等天然含羧酸根有機配子進行水熱自組裝反應，形成掌性金屬-有機配位聚合物。 第一部分的研究中，化合物1-3為二維層狀結構、化合物4為三維網狀結構，TBzIm與剛性含羧酸根有機配位子之立體阻障在結構的自組裝形成過程中，扮演相當重要的角色。第二部分之化合物5為三維網狀結構，由五個二價錳金屬離子(MnII)所形成的金屬中心展現出有趣地反鐵磁性(antiferromagnetic)行為，基態等於S = 15/2，甚為少見。第三部分的研究中，化合物6與7為等結構(isostructure)，具掌性之螺旋型超分子結構，在水熱法的過程中天冬胺酸經由原位反應(in-situ reaction)轉換為反丁烯二酸(fumaric acid)。有趣的是若與直接使用反丁烯二酸進行化合物6與7的合成，則產率顯著降低；化合物8則為含有槳舵形(paddle wheel)進構單元(SBU)的掌性超分子結構。在本論文中，由TBzIm所合成的八種配位聚合物皆展現出良好的熱穩定性，其中以化合物3與8最為穩定，耐熱溫度可達480°C。In this thesis, metal–organic coordination frameworks were prepared by reacting a ligand, 1,3,5-tris(benzimidazoyl-1-ylmethyl)-2,4,6-trimethylbenzene (TBzIm), with transition metal ions (ZnII, CoII, MnII, and NiII) and different carboxylic acids under hydrothermal conditions. We report eight compounds in this study, 4(H3O)+[Zn8(TBzIm)2(btc)4Cl8]•4H2O (1), [Zn12(TBzIm)2(bdc)4Cl16]•3H2O (2), [Co4(TBzIm)4(Hbtc)4] (3), [Co2(TBzIm)2(bdc)2]•3H2O (4), [Mn5Cl10(TBzIm)4]•1acetone (5), [Co2(Fum)2(TBzIm)2]n (6), [Ni2(Fum)2(TBzIm)2]n (7), and [Co12(TBzIm)4(D-Cam)12] (8). A semi-rigid tripodal ligand, TBzIm, was first reacted with different metal ions and aromatic carboxylic acids (trimesic acid, H3Btc and terephthalic acid, H2Bdc) to afford four compounds (1-4) under hydrothermal conditions. Compound 1 was obtained from the reaction of TBzIm, ZnCl2•4H2O, and H3Btc (H3Btc = 1,3,5-benzenetricarboxylic acid). Compound 2 was produced from the self-assembly of TBzIm, ZnCl2•4H2O, and H2Bdc (H2Bdc = 1,4-benzenedicarboxylic acid). Compound 3 was prepared from TBzIm, Co(SO)4•7H2O, and H3Btc. Compound 4 was obtained by reacting TBzIm, Co(SO)4•7H2O, and H2Bdc. In a second series of experiments, TBzIm was reacted with MnCl2•4H2O to produce compound 5, which exhibits a high spin ground state S = 15/2 and shows antiferromagnetic behavior. In a third series, TBzIm was reacted with different metal salts and several chiral carboxylic acids to produce three chiral compounds (6-8). Compound 6 was obtained when TBzIm, CoCl2•6H2O, and aspartic acid were used. Compound 7 was prepared from TBzIm, NiCl2•6H2O, and aspartic acid. Compound 8 was obtained by reacting TBzIm, CoCl2•6H2O, and D-camphoric acid. In the first part, compounds 1-3 adopt 2D layered structures and compound 4 has a 3D framework structure. The steric hindrance of TBzIm and aromatic carboxylic acids play important roles in the architectural engineering of the crystals. In the second part, the [Mn5Cl10] coordination core of compound 5 was found to exhibit interesting magnetic behavior and the TBzIm ligand shows a rarely observed conformation. In the third part, the chiral structures of compounds 6 and 7 were generated into helical arrays via an in-situ process. The chiral structure of compound 8 is constructed from three crystallographically independent binuclear carboxylate complexes {Co2(COO)4}, known as “paddle-wheel” types of secondary building units (SBU).