螺旋聚异腈端功能化与超支化聚异腈的精密合成及其手性分离性能

Inspired by the helical structures and the related functions of biomacromolecules, artificial helical polymers have attracted considerable research attentions in recent years. Polyisocyanide is a class of famous helical polymer owing to its stable helical conformation and a range of appealing applications. In our previous works, we have developed a family of alkyne-Pd(II) catalysts, which can initiate living polymerizations of various isocyanide monomers. However, the Pd(II) complex was located at the end-terminus of the generated helical polyisocyanide, which was too stable to be removed and the end-functionalization is difficult. In this proposal, we attempt to introduce various ligands to the end-Pd(II) unit of the helical polyisocyanides to enhance its reactivity. Thus a variety of functional groups can be installed onto polyisocyanide chain end through appropriate Pd(II)-mediated coupling reactions and simultaneously remove the residue Pd(II) catalyst. Based on the same mechanism, we try to copolymerize functional aryl monomers with the Pd(II)-terminated polyisocyanide to incorporate a conjugated polymer onto helical polyisocyanide chain end, which will lead to the formation of well-defined block copolymers containing helical polyisocyanide and functional conjugated polymers. We will study the controllability and the monomer scope of the block copolymerization. Taking advantage of the end-functionalization method, we will introduce reactive groups onto the two ends of helical polyisocyanide. Through the reactions of the head- and end-groups, we attempt to synthesize hyperbranched helical polyisocyanides, and explore their chiral resolution ability. Through these studies, we want to establish a method for facile synthesis of end-functionalized helical polyisocyanides and hyperbranched polyisocyanides, and develop new functional materials for chiral resolution.

受生物大分子螺旋结构和功能的启发，人们对螺旋高分子产生了极大的研究兴趣。聚异腈是一种典型的螺旋高分子、具有良好的稳定性和广泛的应用前景。前期工作中，我们发展的炔钯配合物可以引发多种异腈单体活性聚合生成立构规整螺旋聚异腈。但是聚合后钯片段停留在聚异腈的末端上，性质稳定，难以转化和脱除。本项目中，我们拟在聚异腈末端钯上引入新的配体提高其反应活性，再通过钯催化的偶联反应将功能基团引入到聚异腈端基上，实现聚异腈端功能化和催化剂脱除；基于类似的原理，我们拟利用聚异腈与芳基单体共聚，将共轭高分子引入到聚异腈上，合成端功能化螺旋聚异腈，并研究共聚反应的可控性和单体普适性；利用聚异腈端功能化的方法，我们拟在聚异腈的首、尾两端引入反应性基团，通过端基间的反应制备超支化螺旋聚异腈，并探索其手性分离性能。本项目的研究工作将为端功能化螺旋聚异腈与超支化聚异腈的合成提供新的方法，为手性分离领域提供新的手性分离材料。

受自然界螺旋结构和功能的启发，人们对螺旋高分子产生了浓厚的研究兴趣。在已报道的螺旋高分子中，聚异腈具有良好的螺旋稳定性和广泛的应用前景。前期工作中，我们发展的炔钯催化剂可以引发异腈活性聚合生成等规立构的螺旋聚异腈。但是聚合后钯片段停留在聚异腈的末端上，性质稳定，难以转化和脱除。本项目中，我们在炔钯催化剂上引入手性的双齿磷配体，利用刚性配体提高炔钯催化剂的活性和定向能力，利用配体的手性控制聚合反应的螺旋选择性和聚异腈的螺旋方向。此外，含有双齿配体的钯配合物易于发生还原消除反应，有利于螺旋聚异腈的端基功能化和催化剂的脱除。通过理性的配体筛选，我们发现在炔钯催化剂上引入手性的双齿BINAP或者Wei-Phos配体得到的手性钯催化剂具有很高的聚合活性，能够引发多种异腈单体活性聚合，生成的螺旋聚异腈的分子量可控制、分子量分布窄。而且刚性配体能够控制单体的插入方向，实现定向聚合，得到等规立构的螺旋聚异腈。配体的手性控制聚合反应的螺旋选择性，得到单手性的P-螺旋或M-螺旋聚异腈。单手性的螺旋聚异腈表现出有趣的螺旋和链长驱动的自分类和有序自组装性质。双齿配体提高了螺旋聚异腈末端钯的活性，能够与多种炔类化合物发生Sonogashira交叉偶联反应，将功能基团或大分子引入的螺旋聚异腈的末端上，实现螺旋聚异腈的端基功能化，同时将末端的钯配合物脱除。我们还设计合成了多臂的炔钯催化剂，并引发异腈活性聚合制备了多臂的螺旋聚异腈，利用活性端基与双异腈发生交联反应，实现了交联螺旋聚异腈的可控合成。交联的螺旋聚异腈还表现出优异的手性分离和吸附性能。本项目的研究工作为手性功能高分子的可控合成提供新的方法，为分离领域发展出了新的手性分离材料。基于这些研究工作我们在Acc. Chem. Res., Angew. Chem. Int. Ed., Nat. Commun., Chem. Sci., Macromolecules/ACS Macro Lett.等国际知名期刊上发表基金标注论文28篇，申请专利4件。通过本项目的研究工作培养硕士研究生12名，博士研究生4名，博士后1名。