We present the synthesis of a B-N analogue of polystyrene, poly(N-methyl-B-vinylazaborine) in high molecular weight (M = 24.9 kDa). Furthermore, it was possible to prepare a copolymer with the C-C analogue. A thorough comparison between the polymers by NMR spectroscopy, TGA, DSC and GPC showed significant differences between these polymers.
Boron–nitrogen
substitutions in polycyclic aromatic hydrocarbons
(PAHs) have a strong impact on the optical properties of the molecules
due to a significantly more heterogeneous electron distribution. However,
besides these single-molecule properties, the observed optical properties
of PAHs critically depend on the degree of intermolecular interactions
such as π–π-stacking, dipolar interactions, or
the formation of dimers in the excited state. Pyrene is the most prominent
example showing the latter as it exhibits a broadened and strongly
bathochromically shifted emission band at high concentrations in solution
compared to the respective monomers. In the solid state, the impact
of intermolecular interactions is even higher as it determines the
crystal packing crucially. In this work, a thiophene-flanked BN-pyrene
(
BNP
) was synthesized and compared with its all-carbon
analogue (
CCP
) in solution and in the solid state by
means of crystallography, NMR spectroscopy, UV–vis spectroscopy,
and photoluminescence (PL) spectroscopy. In solution, PL spectroscopy
revealed the solvent-dependent presence of excimers of
CCP
at high concentrations. In contrast, no excimers were found in
BNP
. Clear differences were also observed in the single-crystal
packing motifs. While
CCP
revealed overlapped pyrene
planes with centroid distances in the range of classical π-stacking
interactions, the
BNP
scaffolds were displaced and significantly
more spatially separated.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.