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

authored by

Yannik Appiarius, Philipp J. Gliese, Stephan A.W. Segler, Pascal Rusch, Jiangbin Zhang, Paul J. Gates, Rumpa Pal, Lorraine A. Malaspina, Kunihisa Sugimoto, Tim Neudecker, Nadja C. Bigall, Simon Grabowsky, Artem A. Bakulin, Anne Staubitz

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.

Organisation(s)

Institute of Physical Chemistry and Electrochemistry
PhoenixD: Photonics, Optics, and Engineering - Innovation Across Disciplines
Section Catalysis and Membranes

External Organisation(s)

University of Bremen
University of Cambridge
National University of Defense Technology
University of Bristol
University of Bern
Japan Synchrotron Radiation Research Institute
Imperial College London

Type

Article

Journal

Journal of Physical Chemistry C

Volume

126

Pages

4563-4576

No. of pages

14

ISSN

1932-7447

Publication date

10.03.2022

Publication status

Published

Peer reviewed

Yes

ASJC Scopus subject areas

Electronic, Optical and Magnetic Materials, Energy(all), Physical and Theoretical Chemistry, Surfaces, Coatings and Films

Electronic version(s)

https://doi.org/10.1021/acs.jpcc.1c08812 (Access: Open)