摘要/Abstract
金属有机笼（Metal-Organic Cages，MOCs）作为一种新型的分子容器，因其具有特殊的空腔结构及其在分子识别/分离、药物传输和催化等方面具有诱人的应用前景而受到****广泛地关注.但是，在过去几十年里，化学家们主要致力于构筑各种具有特定功能的MOCs，而进一步将MOCs组装成先进的超分子材料，在这方面研究较少.在前期工作中，本课题组构筑了一例可溶于水、超稳定且具有配位组装功能的钛-有机四面体笼（Ti4L6，L=帕莫酸），并利用Ti4L6笼作为原料，通过两步反应实现了与不同金属离子的配位组装.在本项工作中，在不同溶剂热的条件下，利用Ti4L6笼分别与Mn2+、Nd3+、Ba2+和Ca2+离子反应，得到了系列Ti4L6-笼基配合物，分别为：（Me2NH2）9（Me4N）[Mn3（Ti4L6）2-（H2O）9（DMF）6]·Guests（PTC-241，DMF=N，N-二甲基甲酰胺）；（Me2NH2）5[Nd（Ti4L6）（H2O）2（DMF）5]·Guests（PTC-242）；（Me2NH2）2[Ba4（Ti4L6）（OH）2（H2O）8（TEA）5]·Guests（PTC-243，TEA=三乙醇胺）；（Me2NH2）2[Ca3（Ti4L6）（H2O）8（DEA）2]·Guests（PTC-244，DEA=二乙醇胺）；（Me2NH2）2[Ca3（Ti4L6）（H2O）15]·Guests（PTC-245），并采用X射线单晶衍射、红外（IR）光谱分析、热分析仪（TGA）和X射线粉末衍射（PXRD）等方法对这些化合物进行了结构表征.X射线单晶衍射结果表明，PTC-241是由ΔΔΔΔ-[Ti4L6]和ΔΔΔΔ-[Ti4L6]-Mn3笼通过弱作用力（氢键和π-π堆积）交错堆积形成的超分子手性化合物；PTC-242是由Ti4L6-Nd笼通过氢键作用堆积形成的超分子化合物；PTC-243是一条直线形的Ti4L6-Ba4链；而PTC-244和PTC-245则是两个具有峰窝状结构的二维Ti4L6-Ca3层.另外，我们还研究了PTC-244和PTC-245的荧光性质.
关键词: 钛有机笼, 多步组装, 合成, 晶体结构
Metal-organic cages (MOCs) as a new type of molecular containers have attracted great interest because of their special cavities and wide applications in molecule recognition and separation, drug delivery and catalysis, etc. However, in the past decades, most researchers just devote to constructing discrete MOCs with special functions. Since many cage compounds are not soluble and stable in the solvent, the further assembly of cages into advanced materials is relatively less developed. In our previous study, we reported a water-soluble and ultrastable Ti4L6 (L=embonate) tetrahedron with coordination assembly function, which has been applied as the starting material to realize coordination assembly with different metal ions through two-step reaction. In this work, by employing the Ti4L6 cages to assemble with Mn2+, Nd3+, Ba2+ and Ca2+ ions, respectively, a series of Ti4L6-based complexes have been synthesized under different solvothermal reaction conditions, namely, (Me2NH2)9(Me4N)[Mn3(Ti4L6)2(H2O)9(DMF)6]·Guests (PTC-241, DMF=N,N-dimethylformamide); (Me2NH2)5- [Nd(Ti4L6)(H2O)2(DMF)5]·Guests (PTC-242); (Me2NH2)2[Ba4(Ti4L6)(OH)2(H2O)8(TEA)5]·Guests (PTC-243, TEA=Triethanolamine); (Me2NH2)2[Ca3(Ti4L6)(H2O)8(DEA)2]·Guests (PTC-244, DEA=Diethanolamine); (Me2NH2)2[Ca3(Ti4L6)- (H2O)15]·Guests (PTC-245). Their structures were characterized by X-ray single crystal diffraction, thermo gravimetric analyzer (TGA), infrared spectroscopy (IR) and powder X-ray diffraction (PXRD). Single-crystal analysis reveals that PTC-241 is a supramolecular homochiral architecture formed by the staggered accumulation of ΔΔΔΔ-[Ti4L6] and ΔΔΔΔ-[Ti4L6]-Mn3 cages by weak interactions (such as hydrogen bonding and π-π stacking). PTC-242 is also a supramolecular structure, in which the Ti4L6-Nd cages are linked by (Me2NH2)+ cations and ethanediamine (en) molecules via the weak N-H…O hydrogen bonding force, giving rise to a 3D H-bonding framework with a honeycomb lattice of hexagonal channels along the b axis. PTC-243 is a linear Ti4L6-Ba4 chain structure. Both PTC-244 and PTC-245 are two-dimensional (2D) Ti4L6-Ca3 layers with honeycomb-like structures. In addition, we also investigated the fluorescent properties of PTC-244 and PTC-245 in the solid state, and the results show that both of them display strong emitting bands in the visible region.
Key words: titanium-organic cage, stepwise assembly, synthesis, crystal structure
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