Stereoselective gridization and polygridization with centrosymmetric molecular packing
Dongqing Lin, Ying Wei, Aizhong Peng, He Zhang, Chunxiao Zhong, Dan Lu, Hao Zhang, Xiangping Zheng, Lei Yang, Quanyou Feng, Linghai Xie, Wei Huang
Abstract
Abstract The gridarenes, with well-defined edges and vertices, represent versatile nanoscale building blocks for the installation of frameworks and architectures but suffer from difficulty in stereoselective control during their synthesis. Here we report a diastereoselective gridization of superelectrophilic diazafluorene-containing substrates (A m B n ) with crescent shapes into Drawing Hands grids (DHGs). The meso -selectivity reaches 75.6% diastereomeric excess ( de ) during the gridization of A 1 B 1 -type substrates and maintains ~80% de during the polygridization of A 2 B 2 -type monomers. Such stereocontrol originates from the centrosymmetric molecular packing of two charge-delocalized superelectrophiles with synergistically π – π stacking attractions and coulombic repulsions. As meso -stereoregular structures show 20∼30 nm in length, the rigid ring/chain-alternating polygrids have a Mark–Houwink exponent of 1.651 and a molecular weight ( M ) dependence of the hydrodynamic radius R h ∼ M 1.13 . Via the simulation of chain collapse, meso -configured polygridarenes still adopt rod-like conformations that facilitate the high rigidity of organic nanopolymers, distinguished from toroid backbones of rac -type polygrids.