Document Type




Format of Original

4 p.

Publication Date



American Chemical Society

Source Publication

Journal of Physical Chemistry Letters

Source ISSN


Original Item ID

DOI: 10.1021/acs.jpclett.6b01201; PubMed Central PMID: 27447947


Exciton formation and charge separation and transport are key dynamical events in a variety of functional polymeric materials and biological systems, including DNA. Beyond the necessary cofacial approach of a pair of aromatic molecules at van der Waals contact, the extent of overlap and necessary geometrical reorganization for optimal stabilization of an excimer vs dimer cation radical remain unresolved. Here, we compare experimentally the dynamics of excimer formation (via emission) and charge stabilization (via threshold ionization) of a novel covalently linked, cofacially stacked fluorene dimer (F2) with the unlinked van der Waals dimer of fluorene, that is, (F)2. Although the measured ionization potentials are identical, the excimeric state is stabilized by up to ∼30 kJ/mol in covalently linked F2. Supported by theory, this work demonstrates for the first time experimentally that optimal stabilization of an excimer requires a perfect sandwich-like geometry with maximal overlap, whereas hole stabilization in π-stacked aggregates is less geometrically restrictive.


Accepted version. Journal of Physical Chemistry Letters, Vol. 7, No. 15 (August 4, 2016): 3042-3045. DOI. © 2016 American Chemical Society. Used with permission.

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