Exciton Coupling and Conformational Changes Impacting the Excited State Properties of Metal Organic Frameworks

Andreas Windischbacher, Luca Steiner, Ritesh Haldar, Christof Wöll, Egbert Zojer*, Anne-Marie Kelterer*

*Corresponding author for this work

Research output: Contribution to journalArticle

Abstract

In recent years, the photophysical properties of crystalline metal-organic frameworks (MOFs) have become increasingly relevant for their potential application in light-emitting devices, photovoltaics, nonlinear optics and sensing. The availability of high-quality experimental data for such systems makes them ideally suited for a validation of quantum mechanical simulations, aiming at an in-depth atomistic understanding of photophysical phenomena. Here we present a computational DFT study of the absorption and emission characteristics of a Zn-based surface-anchored metal-organic framework (Zn-SURMOF-2) containing anthracenedibenzoic acid (ADB) as linker. Combining band-structure and cluster-based simulations on ADB chromophores in various conformations and aggregation states, we are able to provide a detailed explanation of the experimentally observed photophysical properties of Zn-ADB SURMOF-2: The unexpected (weak) red-shift of the absorption maxima upon incorporating ADB chromophores into SURMOF-2 can be explained by a combination of excitonic coupling effects with conformational changes of the chromophores already in their ground state. As far as the unusually large red-shift of the emission of Zn-ADB SURMOF-2 is concerned, based on our simulations, we attribute it to a modification of the exciton coupling compared to conventional H-aggregates, which results from a relative slip of the centers of neighboring chromophores upon incorporation in Zn-ADB SURMOF-2.

Original languageEnglish
Article number4230
Number of pages21
JournalMolecules
Volume25
Issue number18
DOIs
Publication statusPublished - 15 Sep 2020

Keywords

  • Absorption
  • Aggregation
  • Emission
  • Metal organic frameworks
  • SURMOF
  • Time-dependent density functional theory

ASJC Scopus subject areas

  • Drug Discovery
  • Analytical Chemistry
  • Chemistry (miscellaneous)
  • Molecular Medicine
  • Physical and Theoretical Chemistry
  • Pharmaceutical Science
  • Organic Chemistry

Fields of Expertise

  • Advanced Materials Science

Treatment code (Nähere Zuordnung)

  • Basic - Fundamental (Grundlagenforschung)

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