晶态及螺旋结构手性金属有机膦酸化合物的构筑与性能研究

Chirality is a widespread phenomenon in nature. Biological chirality is not only limited to molecular chirality caused by chiral central atom but also includes structural chirality in the topological geometric space. For example, condensation of L-amino acids leads to the formation of chiral peptides, which further assemble into helical proteins through weak intermolecular interactions. It remains a challenging task, however, to achieve chirality transcription and amplification from molecular level to helical structure in synthetic systems such as metal-organic coordination polymers. Such studies will contribute not only to our understanding about the origin of the chirality, but also to the applications of such materials in chiral recognition and separation, asymmetric catalysis, and chiral functional materials. In this project, we shall synthesize homochiral metal phosphonates based on enantiopure aminomethylphosphonic acids with crystalline form. Through modification of the organic ligands, introduction of the second metal ions and careful adjustion of the reaction conditions, we expect that the weak interactions between the chiral molecules can be manipulated. Finally chiral amplification from molecule to helical structure can be achieved. The formation.mechanism of the helices and the regulation of the chiral properties (pitch and diameter) will be studied. The chiral recognition and separation properties as well as the optical and magnetic properties of both the crystals and rhelices will be investigated in detail.

手性是自然界普遍存在的现象。生物手性不仅局限于由手性中心原子引起的分子手性，而且还包括拓扑几何空间的手性螺旋结构。比如由L构型天然氨基酸分子组成手性多肽、进而通过弱相互作用构成手性螺旋蛋白质大分子。如何在人工合成体系中实现手性从分子层次到螺旋结构的传递和放大，是一个极具挑战的课题。相关研究不仅有助于进一步认识手性的起源，而且对手性物质在手性识别和分离、不对称催化、手性功能材料等方面的应用具有十分重要的意义。本项目将选择单一手性的有机胺基膦酸作为配体，组装出单一手性的金属有机膦酸化合物晶态材料，进一步通过修饰有机基团、引入第二金属离子、改变实验条件等手段调控手性分子之间的弱相互作用，使手性得以从分子层次传递到更高层次，获得单一手性螺旋结构材料，揭示螺旋结构的形成机制及调控规律，深入研究手性金属有机膦酸化合物形貌对手性识别和分离作用及光磁性质的影响。

手性是自然界普遍存在的现象。生物体的手性不仅局限于由手性中心原子引起的分子手性，而且还包括拓扑几何空间的手性螺旋结构。如何在人工合成体系中实现手性从分子层次到螺旋结构的传递和放大，是一个极具挑战的课题。相关研究不仅有助于进一步认识手性的起源，而且对手性物质在手性识别和分离、不对称催化、手性功能材料等方面的应用具有十分重要的意义。. 本项目针对“手性传递放大的机制与规律”这一核心科学问题，合成了五对手性有机膦酸配体，与过渡金属或稀土离子组装得到20个结构明确的单一手性晶态金属有机膦酸化合物。通过修饰有机基团、改变反应体系的温度、酸度、抗衡阴离子、盐浓度和溶剂等方式，调控手性分子间的弱相互作用，系统研究各种实验条件对产物形貌的影响，得到一系列具有螺旋结构的单一手性金属有机膦酸材料，提出由环己烷构象变化导致螺旋“链扭曲生长”的新机理，通过pH和阴离子协同调控实现螺旋结构材料的旋向翻转，提出通过盐的浓度调控螺旋结构旋向的新思路，进一步研究了不同形貌对镝有机膦酸化合物磁性的影响。上述工作为探索功能配位聚合物螺旋材料的组装及应用提供了基础。