Pillar[5]arene-based Neutral Radicals with Doublet Red Emissions and Stable Chiroptical Properties

Org Lett. 2022 Mar 18;24(10):1935-1940. doi: 10.1021/acs.orglett.2c00313. Epub 2022 Mar 4.

Abstract

Stable organic radicals with unique luminescence show great importance in photoelectromagnetic materials. We herein report two unusual radical-based systems (P5N-TTM and P5B-TTM) using the concerted effects of planar chiral pillar[5]arenes and tris(2,4,6-trichlorophenyl)methyl (TTM) radicals. The steric effect and electronic doublet-spin character of these radicals allowed the optical resolution and the first red emissions (∼650 nm) for pillar[5]arene derivatives. Notably, cross-coupling with macrocyclic pillar[5]arene, in turn, considerably enhanced the configurational stability of TTM radicals.