基于大环金属配体的金属-有机笼状化合物的可控构筑及其核苷/核苷酸传感应用

In this project, a series of bis- or multi-tacn (tacn = 1,4,7-triazacyclononane) scaffolds bearing planar aromatic cores as well as a combination of separate coordinating groups and non-covalent binding sites in their pendant arms will be prepared for the construction of the rigid metalloligands with transition metals. Then the suitable reaction conditions should be established to achieve the controllable fabrication of homo- or heteronuclear metal-organic cages with different cavity sizes and shapes from such metalloligands, which act as the building blocks, and transition or rare-earth metals through the coordination-driven self-assembly. We will investigate the recognition capability of the metal-organic cages towards various nucleosides/nucleotides in detail, and some factors which influence the confined detection of nucleosides/nucleotides, such as the cavity size of the host cages, the complementary recognition sites and the non-covalent interactions between the host and guest compounds, will be discussed. As a result, much deeper insights on the dominant factors which are responsible for the selectivity of the cage sensors for the recognition of specific nucleoside/nucleotide substrates and the design principles of the metal-organic cages with the specific recognition properties of the studied substrates will be gained. According to this, the recognition and sensing moieties of some selected supramolecular hosts will be tuned so that they may show highly selective and sensitive sensing for the specific nucleoside/nucleotide substrates. In latter project stages, novel metal-organic cages with multiple recognition sites and fluorescent sensing units will be designed and constructed in order to realize the simultaneous detection of distinct nucleoside/nucleotide substrates in a complex system.

本课题拟以一系列含平面芳香核且悬臂上具有分离配位基及非共价作用位点的双/多三氮大环脚手架结合过渡金属形成刚性的金属配体，以其作为结构砌块与过渡或稀土金属经配位驱动自组装获得空腔尺寸与形状各异的同/异金属-有机笼状化合物，探索实现金属-有机笼状化合物可控构筑的适宜条件。研究金属-有机笼状化合物对于各类核苷/核苷酸小分子的识别性能，分析金属-有机笼状化合物主体的空腔尺寸、主客体识别位点的互补性以及非共价相互作用在核苷/核苷酸分子的限域识别中发挥的作用，明确影响主体对特定核苷/核苷酸底物的识别选择性的决定性因素，阐明具有特异性识别与传感性能的笼状化合物主体的设计原则。据此对金属-有机笼状化合物的识别传感单元进行优化，获得数个高选择性与高灵敏度地识别与传感特定核苷/核苷酸底物的超分子主体。设计构建具有多识别位点与多荧光响应单元的金属-有机笼状化合物，实现复杂体系中多核苷/核苷酸底物的同步检测。

金属-有机笼状化合物是一类具有明确外形与特定笼腔的分立型配位组装体，通过在笼腔内预置客体识别元素，可实现其在催化、气体分离、分子识别与传感以及反应中间体捕获等领域的广泛应用。本项目以羧酸功能化单/多氮杂大环脚手架构建的大环金属配体作为结构基元，通过调控组装反应参数、外界刺激以原合成或结构转换等方式可控构筑了一系列同/异金属-有机笼以及多维配位聚合物，阐明了部分金属-有机笼的分步组装机理，揭示了芳香间隔基、侧臂芳基官能团、稀土金属中心等因素对于大环配合物发光性能的影响并以具有不同传感单元的氮杂大环配合物作为单发射/比率型荧光化学探针实现了硝基芳烃污染物的高选择性传感。提出了电化学离子诱导原位剥离以及主-客体作用与超声作用协同剥离制备氮杂大环羧酸或芳香二羧酸二维金属-有机框架超薄纳米片的新策略，纳米化的框架材料具备优异的析氧反应电催化活性并可进行原/分子水平上的性能调控。此外，通过一锅法合成、结构转换以及后合成修饰获得了一系列基于芳香二羧酸的混配型二维稀土金属-有机框架以及二维锌基金属-有机框架，利用上述金属-有机框架作为多功能荧光探针实现了无机离子、有机污染物、生物小分子以及有机溶剂内痕量水分的特异性检测。相关研究对基于大环金属配体策略导向构筑新颖的分立型配位结构具有一定的理论指导意义，拓展了多氮大环及芳香羧酸配合物在荧光传感及电催化领域的应用。项目研究成果已在ACS Sustainable Chem. Eng.，Nanoscale，Dalton Trans.等国际知名SCI期刊上发表7篇学术论文，获得授权国家发明专利1项。