C-H-activated Csp2-Csp3 diastereoselective gridization enables ultraviolet-emitting stereo-molecular nanohydrocarbons with mulitple H•••H interactions

Abstract

Gridization is an emerging molecular integration technology that enables the creation of cross-scale materials by facilitating the generation and their networks of molecular nanohydrocarbon through precise and stepwise linkages. Despite the fact that Friedel-Crafts gridization of fluorenols is powerful, direct linkage among fluorene molecules is challenging owing to the limitation of the Csp2-Csp3 coupling reactions. Herein, we reported an achiral Pd-PPh3-cataylized diastereoselective (> 99:1 d.r.) gridization based on the C-H-activation at the fluorene the 9-position to give dimeric and trimeric windmill-type nanogrids (DWGs and TWGs). The cis-cis-TWGs exhibit unique intramolecular and multiple H•••H interactions with a low field shift to 8.51 ppm, which is rare for hydrocarbon aromatics. Furthermore, these non-conjugated nanogrids show ultraviolet emission behaviors with emission peaks at 361-393 nm in film and 356-373 nm in crystal state, representing the first report of ultraviolet-emitting macrocycles. These nanogrids offer potential nanoscafflolds for ultraviolet organic light-emitting diodes and lasing applications.