Sexithiophene Encapsulated in a Single‐Walled Carbon Nanotube: An In Situ Raman Spectroelectrochemical Study of a Peapod Structure

Abstract

The interaction of single‐walled carbon nanotubes (SWCNTs) and α‐sexithiophene (6T) was studied by Raman spectroscopy and by in situ Raman spectroelectrochemistry. The encapsulation of 6T in SWCNT and its interaction causes a bleaching of its photoluminescence, and also small shifts of its Raman bands. The Raman features of the SWCNT with embedded 6T (6T‐peapods) change in both intensity and frequency compared to those of pristine SWCNT, which is a consequence of a change of the resonant condition. Electrochemical doping demonstrated that the electrode potential applied to the SWCNT wall causes changes in the embedded 6T. The effects of electrochemical charging on the Raman features of pristine SWCNT and 6T@SWCNT were compared. It is shown that the interaction of SWCNT with 6T also changes the electronic structure of SWCNT in its charged state. This change of electronic structure is demonstrated both for semiconducting and metallic tubes.

Electronic Interactions between “Pea” and “Pod”: The Case of Oligothiophenes Encapsulated in Carbon Nanotubes

“…Moreover, charge transfer between a mole­cule and SWNTs always results in a shift of the G‐band and an RBM intensity reduction 19. Again, such effects were not observed, which evidences that charge transfer does not occur in this peapod 30. In addition, a new and symptomatic peak is detected at 1504, 1501, and 1499 cm −1 for 4T, 5T, and 6T peapods, respectively.…”

Raman resonance profile of an individual confined long linear carbon chain

“…by the choice of surfactant in aqueous solutions or bundling effects [23,24,25]. The interior of a nanotube, however, is a highly unperturbed environment which e↵ectively protects encapsulated objects like fullerenes, dye molecules or an additional inner nanotube from external influences [26,27,28,18,29]. This shielding e↵ect is even more pronounced inside double-walled carbon nanotubes, where two concentric walls protect the confined LLCCs.…”

Spectroelectrochemistry of Carbon Nanotubes

“…[50] Among nonfullerene peapods, the a-sexithiopehene peapod was recently studied, demonstrating that SWNT changes their electronic structure as a result of the interaction with the oligomer. [124] 6.3. Double-Walled Carbon Nanotubes Raman spectroelectrochemistry of DWNTs made by pyrolysis of peapods [51,52,98,114,121,125,126] or through chemical vapor deposition (CVD) [69,73] provides an easy distinction of outer/inner tubes of DWNTs in the region of the RBM bands.…”

“…[64,66] There are only a few works on other peapods. [50,124] The encapsulated endohedral fullerene, Dy 3 N@C 80 @SWNT exhibited amphoteric bleaching of fullerene-related features, similarly to C 70 @SWNT, and was also transferable to double welled carbon nanotubes by vacuum calcination (Section 6.3). [50] Among nonfullerene peapods, the a-sexithiopehene peapod was recently studied, demonstrating that SWNT changes their electronic structure as a result of the interaction with the oligomer.…”