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Synthesis and Chiroptical Properties of Hexa‐, Octa‐, and Deca‐azaborahelicenes: Influence of Helicene Size and of the Number of Boron Atoms
Author(s) -
Shen Chengshuo,
SrebroHooper Monika,
Jean Marion,
Vanthuyne Nicolas,
Toupet Loïc,
Williams J. A. Gareth,
Torres Alexis R.,
Riives Adrian J.,
Muller Gilles,
Autschbach Jochen,
Crassous Jeanne
Publication year - 2017
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201604398
Subject(s) - helicene , hexa , circular dichroism , boron , enantiopure drug , chemistry , phosphorescence , crystallography , luminescence , photochemistry , fluorescence , materials science , physics , optoelectronics , optics , molecule , enantioselective synthesis , organic chemistry , catalysis
Four members of a new class of cycloborylated hexa‐, octa‐, and deca‐helicenes ( 1 a – d ) have been prepared in enantiopure form, along with two cycloplatinated deca‐helicenes ( 1 d′ , 1 d 1 ), further extending the family of cycloplatinated hexa‐ and octa‐helicenes reported previously. The azabora[ n ]helicenes display intense electronic circular dichroism and large optical rotations; the dependence of the optical activity on the size of the helix ( n= 6, 8, 10) and the number of boron atoms (1 or 2) has been examined in detail both experimentally and theoretically. The photophysical properties (nonpolarized and circularly polarized luminescence) of these new fluorescent organic helicenes have been measured and compared with the corresponding organometallic phosphorescent cycloplatinated derivatives ( 1 a 1 – d 1 ).