萘基柔性内修饰分子笼的合成、识别与手性传感

SYNTHESIS, RECOGNITION AND CHIRALITY SENSING OF NAPHTHALENE-BASED FLEXIBLE ENDO-FUNCTIONALIZED MOLECULAR CAGES

卢崧博

11749048

硕士

化学

蒋伟

2019-05-20

2019-07-10

哈尔滨工业大学

深圳

超分子化学是化学研究领域的重要分支。大环主体化合物是超分子化学的主要研究工具。相对于大环主体分子，具有三维空腔结构的笼状主体分子通常具有独特的物理、化学性质以及更为优异的主客体键合性能。而用共价键连接的有机分子笼，相比于配位组装分子笼与动态共价分子笼，往往具有更好的动力学稳定性。现在已经报道出来的共价分子笼中，既有柔性的又有刚性的。刚性结构具有更好的预组织性，在主客体键合的过程中可以减少构象的变化，从而降低熵减等不利因素。然而，太过刚性的空腔要求客体的尺寸、形状等方面必须完美匹配，否则键合强度就会大大降低。而赋予主体空腔一定程度的柔性，有利于主体分子根据目标客体的结构进行诱导适合，形成更加匹配的主客体键合，能够实现多种弱相互作用的协同。柔性空腔由构象调整而造成的熵不利因素，可以通过增加主客体作用的位点，由焓来弥补。在此理念的指导下，一类具有一定柔性且有多个富电子芳环的共价分子笼被设计了出来。采用醚氧键将 2 个苯环与 3 个芳香侧壁连接起来形成目标分子笼。柔性的醚键不但能赋予分子笼一定的构象自由度，其氧原子也有可能朝向空腔内部（“内修饰”的理念），而与键合的客体形成额外的相互作用。多作用位点的协同效应弥补了柔性空腔带来的熵不利影响。在本项目中，合成了一种符合上述设计理念的分子笼——基于2,3-二羟基萘的分子笼（命名为“2,3-naphthocage”，简称为“2,3-NC”）。详细研究了分子笼2,3-NC的结构特征和其对有机阳离子的识别行为，并探索了其在多种有机阳离子的高灵敏度检测和手性传感上的应用。

Supramolecular chemistry is an important branch of chemistry research. Macrocyclic host compounds are important tools for studying supramolecular chemistry. Compared to macrocyclic hosts, molecular cages with three-dimensional cavities usually have unique physical and chemical properties and better host-guest binding performance. Particularly, organic covalent molecular cages constructed by covalent bonds tend to have better dynamic stability than those cages that are constructed through metal coordination or dynamic covalent bonds. Covalent molecular cages reported in literature, usually have either flexible or rigid structure. Rigid structure is pre-organized, and undergo small or no conformational changes in the process of host-guest binding, reducing unfavorable entropic cost. However, too rigid structure requires guest molecules must perfectly fit the cavities of the cages in terms of size, shape and electrostatics. Otherwise, the binding will be seriously weakened. Certain degree of flexibility would permit the cavity to induced-fit according to the structure of guests. This would be good for a tight and strong host-guest binding. Entropic penalty due to conformational change would be compensated by enthalpic gain through better host-guest interactions with more binding sites. Under the guidance of this concept, we designed a new flexible molecular cages with multiple electron-rich aromatic sidewalls. The ether bonds were used to connect two benzene rings with three aromatic sidewalls to form the target molecular cages. Flexible ether bonds can give the molecular cage a certain degree of freedom to adjust its conformation, and the oxygen atoms on the ether bonds are possible to direct toward the cavity (“endo-functionalized” concept). So that additional interactions with the guests may form. Herein, we reported the molecular cage in line with the above design concept -- a 2,3-naphthol-based cage (so-called “2,3-naphthocage”, or “2,3-NC” for short). Structural characterizations of 2,3-NC and its recognition behavior to organic cations were studied in detail, and the applications of 2,3-NC in high sensitivity detection of various organic cations and chiral sensing were explored as well.

超分子化学 主客体作用 有机合成 分子笼 分子识别

supramolecular chemistry host-guest interaction molecular recognition organic synthesis molecular cage

中文

联合培养

南方科技大学

卢崧博. 萘基柔性内修饰分子笼的合成、识别与手性传感[D]. 深圳. 哈尔滨工业大学,2019.