Modular Synthesis of Organoboron Helically Chiral Compounds: Cutouts from Extended Helices.
Angew Chem Int Ed Engl
; 60(8): 4350-4357, 2021 Feb 19.
Article
em En
| MEDLINE
| ID: mdl-33244880
ABSTRACT
Two types of helically chiral compounds bearing one and two boron atoms were synthesized by a modular approach. Formation of the helical scaffolds was executed by the introduction of boron to flexible biaryl and triaryl derived from small achiral building blocks. All-ortho-fused azabora[7]helicenes feature exceptional configurational stability, blue or green fluorescence with quantum yields (Φfl ) of 18-24 % in solution, green or yellow solid-state emission (Φfl up to 23 %), and strong chiroptical response with large dissymmetry factors of up to 1.12×10-2 . Azabora[9]helicenes consisting of angularly and linearly fused rings are blue emitters exhibiting Φfl of up to 47 % in CH2 Cl2 and 25 % in the solid state. As revealed by the DFT calculations, their P-M interconversion pathway is more complex than that of H1. Single-crystal X-ray analysis shows clear differences in the packing arrangement of methyl and phenyl derivatives. These molecules are proposed as primary structures of extended helices.
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01-internacional
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MEDLINE
Idioma:
En
Ano de publicação:
2021
Tipo de documento:
Article