%0 Generic
%A Ishibashi, Jacob
S. A.
%A Marshall, Jonathan
L.
%A Mazière, Audrey
%A Lovinger, Gabriel J.
%A Li, Bo
%A Zakharov, Lev N.
%A Dargelos, Alain
%A Graciaa, Alain
%A Chrostowska, Anna
%A Liu, Shih-Yuan
%D 2014
%T Two BN
Isosteres of Anthracene: Synthesis and Characterization
%U https://acs.figshare.com/articles/dataset/Two_BN_Isosteres_of_Anthracene_Synthesis_and_Characterization/2240896
%R 10.1021/ja508813v.s002
%2 https://acs.figshare.com/ndownloader/files/3876838
%K reactivity behavior
%K HOMO energy levels
%K emission λ max values
%K 26. BN anthracenes 1
%K BN anthracenes
%K UV
%K HOMO energy trend
%K BN anthracene 1
%X The synthesis of two parental BN
anthracenes, 1 and 2, was developed, and
their electronic structure and reactivity
behavior were characterized in direct comparison with all-carbon anthracene.
Gas-phase UV-photoelecton spectroscopy studies revealed the following
HOMO energy trend: anthracene, −7.4 eV; BN anthracene 1, −7.7 eV; bis-BN anthracene 2, −8.0
eV. The λmax of the lower energy band in the UV–vis
absorption spectrum is as follows: anthracene, 356 nm; BN anthracene 1, 359 nm; bis-BN anthracene 2, 357 nm. Thus,
although the HOMO is stabilized with increasing BN incorporation,
the HOMO–LUMO band gap remains unchanged across the anthracene
series. The emission λmax values for the three investigated
anthracene compounds are at 403 nm. The pKa values of the N-H proton for BN anthracene 1 and bis-BN anthracene 2 were determined to
be approximately 26. BN anthracenes 1 and 2 do not undergo heat- or light-induced cycloaddition reactions or
Friedel–Crafts acylations. Electrophilic bromination of BN
anthracene 1 with Br2, however, occurs regioselectively
at the 9-position. The reactivity behavior and regioselectivity of
bromination of BN anthracenes are consistent with the electronic structure
of these compounds; i.e., (1) the lower HOMO energy levels for BN
anthracenes stabilize the molecules against cycloaddition and Friedel–Crafts
reactions, and (2) the HOMO orbital coefficients are consistent with
the observed bromination regioselectivity. Overall, this work demonstrates
that BN/CC isosterism can be used as a molecular design strategy to
stabilize the HOMO of acene-type structures while the optical band
gap is maintained.
%I ACS Publications