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Near‐Infrared Quadrupolar Chromophores Combining Three‐Coordinate Boron‐Based Superdonor and Superacceptor Units
Author(s) -
Stennett Tom E.,
Bissinger Philipp,
Griesbeck Stefanie,
Ullrich Stefan,
Krummenacher Ivo,
Auth Michael,
Sperlich Andreas,
Stolte Matthias,
Radacki Krzysztof,
Yao ChangJiang,
Würthner Frank,
Steffen Andreas,
Marder Todd B.,
Braunschweig Holger
Publication year - 2019
Publication title -
angewandte chemie international edition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.831
H-Index - 550
eISSN - 1521-3773
pISSN - 1433-7851
DOI - 10.1002/anie.201900889
Subject(s) - chromophore , homo/lumo , acceptor , crystallography , chemistry , conjugated system , absorption (acoustics) , molecule , electron acceptor , spectroscopy , boron , cyclic voltammetry , photochemistry , pyridine , fluorescence , materials science , electrochemistry , organic chemistry , physics , optics , electrode , quantum mechanics , composite material , condensed matter physics , polymer
Abstract Herein, two new quadrupolar acceptor‐π‐donor‐π‐acceptor (A‐π‐D‐π‐A) chromophores have been prepared featuring a strongly electron‐donating diborene core and strongly electron‐accepting dimesitylboryl (BMes 2 ) and bis(2,4,6‐tris(trifluoromethyl)phenyl)boryl (B F Mes 2 ) end groups. Analysis of the compounds by NMR spectroscopy, X‐ray crystallography, cyclic voltammetry, and UV/Vis‐NIR absorption and emission spectroscopy indicated that the compounds have extended conjugated π‐systems spanning their B 4 C 8 cores. The combination of exceptionally potent π‐donor (diborene) and π‐acceptor (diarylboryl) groups, both based on trigonal boron, leads to very small HOMO–LUMO gaps, resulting in strong absorption in the near‐IR region with maxima in THF at 840 and 1092 nm and very high extinction coefficients of ca. 120 000 m −1 cm −1 . Both molecules also display weak near‐IR fluorescence with small Stokes shifts.