On the Importance of Electronic Symmetry for Triplet State Delocalization.

Journal Article

The influence of electronic symmetry on triplet state delocalization in linear zinc porphyrin oligomers is explored by electron paramagnetic resonance techniques. Using a combination of transient continuous wave and pulse electron nuclear double resonance spectroscopies, it is demonstrated experimentally that complete triplet state delocalization requires the chemical equivalence of all porphyrin units. These results are supported by density functional theory calculations, showing uneven delocalization in a porphyrin dimer in which a terminal ethynyl group renders the two porphyrin units inequivalent. When the conjugation length of the molecule is further increased upon addition of a second terminal ethynyl group that restores the symmetry of the system, the triplet state is again found to be completely delocalized. The observations suggest that electronic symmetry is of greater importance for triplet state delocalization than other frequently invoked factors such as conformational rigidity or fundamental length-scale limitations.

Full Text

Duke Authors

Cited Authors

  • Richert, S; Bullard, G; Rawson, J; Angiolillo, PJ; Therien, MJ; Timmel, CR

Published Date

  • April 2017

Published In

Volume / Issue

  • 139 / 15

Start / End Page

  • 5301 - 5304

PubMed ID

  • 28353344

Electronic International Standard Serial Number (EISSN)

  • 1520-5126

International Standard Serial Number (ISSN)

  • 0002-7863

Digital Object Identifier (DOI)

  • 10.1021/jacs.7b01204

Language

  • eng