On the role of excitonic interactions in carotenoid–phthalocyanine dyads and implications for photosynthetic regulation

Authors: Liao, P.-N., Pillai, S., Kloz, M., Gust, D., Moore, A. L., Moore, T. A., Kennis, J. T. M., van Grondelle, R., Walla, P. J.
Title: On the role of excitonic interactions in carotenoid–phthalocyanine dyads and implications for photosynthetic regulation
Source: Photosynthesis Research
Year: 2012
Volume: 111
Pages: 237–243

ABSTRACT:

In two recent studies, energy transfer was reported in certain phthalocyanine–carotenoid dyads between the optically forbidden first excited state of carotenoids (Car S1) and phthalocyanines (Pcs) in the direction Pc -> Car S1 (Kloz et al., J Am Chem Soc 133:7007–7015, 2011) as well as in the direction Car S1 -> Pc (Liao et al., J Phys Chem A115:4082–4091, 2011). In this article, we show that the extent of this energy transfer in both directions is closely correlated in these dyads. This correlation and the additional observation that Car S1 is instantaneously populated after Pc excitation provides evidence that in these compounds excitonic interactions can occur. Besides pure energy transfer and electron transfer, this is the third type of tetrapyrrole–carotenoid interaction that has been shown to occur in these model compounds and that has previously been proposed as a photosynthetic regulation mechanism. We discuss the implications of these models for photosynthetic regulation. The findings are also discussed in the context of a model in which both electronic states are disordered and in which the strength of the electronic coupling determines whether energy transfer, excitonic coupling, or electron transfer occurs.


Date of online publication: Fri, 2011-09-23
Center for Bio-Inspired Solar Fuel Production 
Arizona State University, Room ISTB-5 101, Box 871604, Tempe, AZ 85287-1604 
phone: (480) 965-1548 | fax: (480) 965-5927 | Contact Us