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BN-Substitution in Dithienylpyrenes Prevents Excimer Formation in Solution and in the Solid State.

Published version
Peer-reviewed

Type

Article

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Authors

Gliese, Philipp J 
Segler, Stephan AW 
Rusch, Pascal 
Zhang, Jiangbin 

Abstract

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.

Description

Keywords

3402 Inorganic Chemistry, 34 Chemical Sciences

Journal Title

J Phys Chem C Nanomater Interfaces

Conference Name

Journal ISSN

1932-7447
1932-7455

Volume Title

Publisher

American Chemical Society (ACS)
Sponsorship
European Research Council (714429)