Ultrafast Dynamics of meso-Tetraphenylmetalloporphyrins: The Role of Dark States
2013 (English)In: CHEMPLUSCHEM, ISSN 2192-6506, Vol. 78, no 10, 1244-1251 p.Article in journal (Refereed) Published
Studying the relaxation pathways of porphyrins and related structures upon light absorption is crucial to understand the fundamental processes of light harvesting in biosystems and many applications. Herein, we show by means of transient absorption studies, following Q- and Soret-band excitation, and abinitio calculations on meso-tetraphenylporphyrinato magnesium(II) (MgTPP) and meso-tetraphenylporphyrinato cadmium(II) (CdTPP) that electronic relaxation following Soret-band excitation of porphyrins with a heavy central atom is mediated by a hitherto disregarded dark state. This accounts for an increased rate of internal conversion. The dark state originates from an orbital localized at the central nitrogen atoms and its energy continuously decreases along the series from magnesium to zinc to cadmium to below 2.75eV for CdTPP dissolved in tetrahydrofuran. Furthermore, we are able to directly trace fast intersystem crossing in the cadmium derivative, which takes place within (110 +/- 20)ps.
Place, publisher, year, edition, pages
2013. Vol. 78, no 10, 1244-1251 p.
dark states, density functional calculations, femtosecond spectroscopy, porphyrinoids
IdentifiersURN: urn:nbn:se:su:diva-96105DOI: 10.1002/cplu.201300143ISI: 000325548600009OAI: oai:DiVA.org:su-96105DiVA: diva2:664058
Deutsche Forschungsgemeinschaft (DFG:) State Baden-Wurttemberg Karlsruhe Institute of Technology (KIT) through the Center for Functional Nanostructures (CFN) C3.2, C3.5; Humboldt-Foundation; Wenner-Gren Foundation ; DFG Cluster of Excellence: Munich Centre for Advanced Photonics 2013-11-132013-11-112013-11-13Bibliographically approved