Khazeber Ravichandran, Pathak Sourav, Sureshan Kana M
School of Chemistry, Indian Institute of Science Education and Research, Thiruvananthapuram, Kerala, India.
Nat Commun. 2024 Aug 5;15(1):6639. doi: 10.1038/s41467-024-50948-z.
Circumventing the issues of conventional stereocomplexation of preformed polymers, herein, we synthesize two enantiopure polymers of opposite chirality simultaneously and in situ as their 1:1 stereocomplex via topochemical polymerization. We design and synthesize an inositol-based achiral monomer for topochemical ene-azide cycloaddition (TEAC) polymerization. In the crystal, the monomer exhibits conformational enantiomerism, and its conformational enantiomers are self-sorted in an arrangement for TEAC polymerization to yield two enantiopure polymers of opposite chirality. Upon heating the monomer crystals, each self-sorted set of conformational enantiomers undergoes regio- and stereospecific polymerization in a single-crystal-to-single-crystal fashion, generating two 1, 4-triazolinyl-linked polymers of opposite chirality simultaneously. The new chiral carbons in all the triazoline rings of a particular polymer chain have the same absolute configuration. These homochiral polymer strands align parallelly, forming a layer, and such enantiopure layers of opposite chirality stack alternately, forming a perfect 1:1 stereocomplex, which we confirmed using single-crystal XRD analysis.
本文通过拓扑化学聚合同时原位合成了两种具有相反手性的对映体纯聚合物，形成它们1:1的立体复合物，从而规避了预制聚合物传统立体复合的问题。我们设计并合成了一种基于肌醇的非手性单体用于拓扑化学烯-叠氮环加成（TEAC）聚合。在晶体中，该单体表现出构象对映异构，其构象对映体以一种用于TEAC聚合的排列方式进行自分类，以产生两种具有相反手性的对映体纯聚合物。加热单体晶体时，每组自分类的构象对映体以单晶到单晶的方式进行区域和立体特异性聚合，同时生成两种具有相反手性的1,4-三唑啉基连接的聚合物。特定聚合物链的所有三唑啉环中的新手性碳具有相同的绝对构型。这些同手性聚合物链平行排列形成一层，并且这种具有相反手性的对映体纯层交替堆叠，形成完美的1:1立体复合物，我们通过单晶XRD分析证实了这一点。
