Photoinduced formation and characterization of electron-hole pairs in Azaxanthylium derivatized short Single Wall Carbon Nanotubes (CNT).

ROBERTO MARTIN; LILIANA B. JIMENEZ; MERCEDES ALVARO; J. C. SCAIANO; HERMENEGILDO GARCIA

CHEMISTRY-A EUROPEAN JOURNAL

Wiley-VCH Verlag GmbH & Co.

Año: 2009

0947-6539

2-Azaxanthone, a nitrogenated derivative of the well studied organic chromophore xanthone, has been covalently bound through 2-(ethylthio)ethylamido linkers to thecarboxylic acid groups of short, soluble single-walled carbon nanotubes (CNTs) of 500 nm average length, and the resulting azaxanthylium-functionalised CNT (AZX-CNT) (8.5 wt % AZX content) characterised by solution 1H NMR, Raman and IR spectroscopy andthermogravimetric analysis. Comparison of the quenching of the triplet excited state of AZX (steadystate and time-resolved) and of the transient optical spectra of CNTs andAZX-CNT shows that the covalent linkage boosts the interaction between the azaxanthylium moiety and the shortened CNT units. The triplet excited state of the azaxanthylium derivative is quenched by CNT with and without covalent bonding, butwhen it is covalently bonded, the singular transient spectrum is compatible with the photogeneration of electron holes through electron transfer from CNT to excited azaxanthylium units.