Preparation and photochemistry of single wall carbon nanotubes having covalently anchored viologen units

Mercedes Alvaro, Carmela Aprile, Pedro Atienzar, Hermenegildo Garcia

Research output: Contribution to journalArticlepeer-review

Abstract

An asymmetrically substituted viologen (V) has been covalently anchored to single wall carbon nanotube (SWNT) through an ester linkage by reacting chlorinated purified SWNT with N-methyl-N-(6-hydroxyhexyl)4,4′-bipyridine. Spectroscopic evidence for the covalent bond of viologen in V-SWNT comes from the chemical shift of the -CH2-O-CO-methylene group in 1H NMR and from the variations of the 1590 and 1380 cm-1 bands in the Raman spectrum of the V-SWNT with respect to SWNT. The fact that the estimated quenching constant of the SWNT emission by viologen is about 2 orders of magnitude higher than the diffusion coefficient indicates the occurrence of a static quenching arising from the formation of a nonemissive viologen-SWNT complex. Laser flash photolysis shows the formation of viologen radical cation upon direct excitation of V-SWNT. The viologen moiety of V-SWNT is able to form a charge-transfer complex with 2,6-dimethoxynaphthalene (DMN) as evidenced by optical spectroscopy and, upon selective photoexcitation in the charge-transfer band, this V-DMN complex anchored to SWNT gives rise to the corresponding charge separated state decaying in the submillisecond time scales.

Original languageEnglish
Pages (from-to)7692-7697
Number of pages6
JournalJournal of physical chemistry B
Volume109
Issue number16
DOIs
Publication statusPublished - 28 Apr 2005

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