School of Applied and Interdisciplinary Sciences, Indian Association for the Cultivation of Science, 2A and 2B Raja S. C. Mullick Road, Jadavpur, Kolkata 700032, India.
Institute of Chemical Technology Mumbai-IOC Odisha Campus Bhubaneswar, IIT Kharagpur Extension Centre, Bhubaneswar 751013, India.
J Am Chem Soc. 2023 Mar 8;145(9):5270-5284. doi: 10.1021/jacs.2c12894. Epub 2023 Feb 16.
This study unravels the intricate kinetic and thermodynamic pathways involved in the supramolecular copolymerization of the two chiral dipolar naphthalene monoimide (NMI) building blocks ( and ), differing merely by a single heteroatom (oxygen vs sulfur). exhibits distinct supramolecular polymerization features as compared to in terms of its pathway complexity, hierarchical organization, and chiroptical properties. Two distinct self-assembly pathways in occur due to the interplay between the competing dipolar interactions among the NMI chromophores and amide-amide hydrogen (H)-bonding that engenders distinct nanotapes and helical fibers, from its antiparallel and parallel stacking modes, respectively. In contrast, the propensity of to form only a stable spherical assembly is ascribed to its much stronger amide-amide H-bonding, which outperforms other competing interactions. Under the thermodynamic route, an equimolar mixture of the two monomers generates a temporally controlled chiral statistical supramolecular copolymer that autocatalytically evolves from an initially formed metastable spherical heterostructure. In contrast, the sequence-controlled addition of the two monomers leads to the kinetically driven hetero-seeded block copolymerization. The ability to trap in a metastable state allows its secondary nucleation from the surface of the thermodynamically stable spherical "seed", which leads to the core-multiarmed "star" copolymer with reversibly and temporally controllable length of the growing "arms" from the "core". Unlike the one-dimensional self-assembly of and its random co-assembly with , which are both chiral, unprecedentedly, the preferred helical bias of the nucleating fibers is completely inhibited by the absence of stereoregularity of the "seed" in the "star" topology.
本研究揭示了两种手性二极 naphthalene monoimide（NMI）构筑块（和）超分子共聚所涉及的复杂动力学和热力学途径，这两种构筑块仅差一个杂原子（氧与硫）。与相比，在其途径复杂性、层次组织和手性光学性质方面，表现出明显的超分子聚合特征。由于 NMI 发色团之间的竞争偶极相互作用和酰胺-酰胺氢键的相互作用，在中存在两种不同的自组装途径，这导致了分别来自其反平行和平行堆积模式的独特纳米带和螺旋纤维。相比之下，倾向于形成仅稳定的球形组装是由于其更强的酰胺-酰胺氢键，这超过了其他竞争相互作用。在热力学途径下，两种单体的等摩尔混合物生成了一种时间控制的手性统计超分子共聚物，该共聚物自最初形成的亚稳球形杂结构自动催化演变而来。相比之下，两种单体的序列控制添加导致了动力学驱动的杂种子嵌段共聚。将捕获在亚稳状态的能力允许其从热力学稳定的球形“种子”的表面进行二次成核，这导致了具有可逆和时间可控的增长“臂”长度的多核-多臂“星”共聚物，这些“臂”从“核”生长。与一维自组装的不同，和其具有手性的随机共聚，前所未有的是，成核纤维的螺旋偏好被“星”拓扑中“种子”的缺乏立体规整性完全抑制。
