Elucidating aggregation pathways in the donor–acceptor type molecules p-DTS(FBTTh2)2 and p-SIDT(FBTTh2)2

Bourdick, A., Reichenberger, M., Stradomska, A., Bazan, G. C., Nguyen, T.-Q., Köhler, A. and Gekle, S. (2018) Elucidating aggregation pathways in the donor–acceptor type molecules p-DTS(FBTTh2)2 and p-SIDT(FBTTh2)2. Journal of Physical Chemistry B, 122(39), pp. 9191-9201. (doi: 10.1021/acs.jpcb.8b06283) (PMID:30204437)

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Abstract

We investigated the aggregation behavior of the donor–acceptor molecules p-DTS(FBTTh2)2 (T1) and p-SIDT(FBTTh2)2 (H1) in MTHF solutions. Using optical spectroscopy, we found that T1 forms aggregates in solution while H1 aggregates only when processed as a thin film, but not in solution. Free energy molecular dynamics (MD) simulations based on force fields derived from quantum-mechanical density functional theory fully reproduce this difference. Our simulations reveal that this difference is not due to the lengthy carbon side chains. Rather, the molecular symmetry of T1 allows for an aggregated state in which the central donor units are spatially well-separated while a similar configuration is sterically impossible for H1. As a consequence, any aggregation of H1 necessarily involves aggregation of the central donors which requires, as a first step, stripping the central donor of its protective MTHF solvation shell. This unfavorable process leads to a significant kinetic hindrance for aggregation and explains the strongly differing aggregation behavior of T1/H1 in MTHF despite their otherwise similar structures.

Item Type:Articles
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:Stradomska-Szymczak, Dr Anna
Authors: Bourdick, A., Reichenberger, M., Stradomska, A., Bazan, G. C., Nguyen, T.-Q., Köhler, A., and Gekle, S.
College/School:College of Science and Engineering > School of Chemistry
Journal Name:Journal of Physical Chemistry B
Publisher:American Chemical Society
ISSN:1520-6106
ISSN (Online):1520-5207
Published Online:11 September 2018

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