Coordinative Interactions between Porphyrins and C60, La@C82, and La2@C80. Issue 2 (23rd November 2012)

• Record Type: Journal Article
• Authors: Tsuchiya, Takahiro; Rudolf, Marc; Wolfrum, Silke; Radhakrishnan, Shankara Gayathri; Aoyama, Ryo; Yokosawa, Yuya; Oshima, Azusa; Akasaka, Takeshi; Nagase, Shigeru; Guldi, Dirk M.
• Is Part Of: Chemistry. Volume 19:Issue 2(2013)
• Page Start: 558
• Page End: 565
• Publication Date: 2012-11-23
• Subjects: Chemistry -- Periodicals; 540
• DOI: 10.1002/chem.201202661
• Languages: English
• ISSNs: 0947-6539

Abstract

<abstract abstract-type="main" xml:lang="en"> <title>Abstract</title> <p>For the first time, a C<sub>60</sub> derivative (<bold>1</bold>) and two different lanthanum metallofullerene derivatives, La@C<sub>82</sub>Py (<bold>2</bold>) and La<sub>2</sub>@C<sub>80</sub>Py (<bold>3</bold>), that feature a pyridyl group as a coordination site for transition‐metal ions have been synthesized and integrated as electron acceptors into coordinative electron‐donor/electron‐acceptor hybrids. Zinc tetraphenylporphyrin (<bold>ZnP</bold>) served as an excited‐state electron donor in this respect. Our investigations, by means of steady‐state and time‐resolved photophysical techniques found that electron transfer governs the excited‐state deactivation in all of these systems, namely <bold>1/ZnP</bold>, <bold>2/ZnP</bold>, and <bold>3/ZnP</bold>, whereas, in the ground state, notable electronic interactions are lacking. Variation of the electron‐accepting fullerene or metallofullerene moieties provides the incentive for fine‐tuning the binding constants, the charge‐separation kinetics, and the charge‐recombination kinetics. To this end, the binding constants, which ranged from log <italic>K</italic><sub>assoc</sub>=3.94–4.38, are dominated by axial coordination, with minor contributions from the orbital overlap of the curved and planar π systems. The charge‐separation and charge‐recombination kinetics, which are in the order of 10<sup>10</sup> and 10<sup>8</sup> s<sup>−1</sup>, relate to the reduction potential of the fullerene and metallofullerenes, respectively.</p> </abstract>