Stereoselective gridization and polygridization with centrosymmetric molecular packing.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 32273512.
- Also identified by DOI 10.1038/s41467-020-15401-x and PMC identifier 7145858.
- Licence recorded as CC BY.
- The licence permits redistribution, so the abstract is shown in full and the full text is available from the publisher.
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<sub>m</sub>B<sub>n</sub>) with crescent shapes into Drawing Hands grids (DHGs). The meso-selectivity reaches 75.6% diastereomeric excess (de) during the gridization of A<sub>1</sub>B<sub>1</sub>-type substrates and maintains ~80% de during the polygridization of A<sub>2</sub>B<sub>2</sub>-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<sub>h</sub> ∼ M<sup>1.13</sup>. 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.