AbstractThe synthesis of a series of triangular‐shaped tricarboxamides endowed with three picoline or nicotine units (compounds 2 and 3, respectively) or just one nicotine unit (compound 4) is reported, and their self‐assembling features investigated. The pyridine rings make compounds 2–4 electronically complementary with our previously reported oligo(phenylene ethynylene)tricarboxamides (OPE‐TA) 1 to form supramolecular copolymers. C3‐symmetric tricarboxamide 2 forms highly stable intramolecular five‐membered pseudocycles that impede its supramolecular polymerization into poly‐2 and the co‐assembly with 1 to yield copolymer poly‐1‐co‐2. On the other hand, C3‐symmetric tricarboxamide 3 readily forms poly‐3 with great stability but unable to form helical supramolecular polymers despite the presence of the peripheral chiral side chains. The copolymer poly‐1‐co‐3 can only be obtained by a previous complete disassembly of the constitutive homopolymers in CHCl3. Helical poly‐1‐co‐3 arises in a process involving the transfer of the helicity from racemic poly‐1 to poly‐3, and the amplification of asymmetry from chiral poly‐3 to poly‐1. Importantly, C2v‐symmetric 4, endowed with only one nicotinamide moiety and three chiral side chains, self‐assembles into a P‐type helical supramolecular polymer (poly‐4) in a thermodynamically controlled cooperative process. The combination of poly‐1 and poly‐4 generates chiral supramolecular copolymer poly‐1‐co‐4, whose blocky microstructure has been investigated by applying the previously reported supramolecular copolymerization model.
摘要 报告合成了一系列具有三个吡啶或烟碱单元(分别为化合物 2 和 3)或只有一个烟碱单元(化合物 4)的三角形三羧酰胺,并研究了它们的自组装特征。吡啶环使化合物 2-4 与我们之前报道的低聚(苯乙炔基)三羧酰胺(OPE-TA)1 具有电子互补性,可形成超分子共聚物。C3 对称三甲酰胺 2 形成高度稳定的分子内五元假环,阻碍其超分子聚合成聚合物-2,并与 1 共同组装生成共聚物聚合物-1-co-2。另一方面,C3-对称三甲酰胺 3 很容易形成聚-3,而且非常稳定,但尽管存在外周手性侧链,却无法形成螺旋超分子聚合物。只有在 CHCl3 中完全分解构成均聚物,才能得到共聚物 poly-1-co-3。外消旋多聚物-1 的螺旋性转移到多聚物-3,手性多聚物-3 的不对称性放大到多聚物-1,螺旋多聚物-1-co-3 就这样产生了。重要的是,只有一个烟酰胺分子和三个手性侧链的 C2v 对称 4 在热力学控制的合作过程中自组装成 P 型螺旋超分子聚合物(poly-4)。聚-1 和聚-4 的结合生成了手性超分子共聚物聚-1-co-4,通过应用之前报道的超分子共聚模型对其块状微观结构进行了研究。