Publication Type Journal Article
Title Polyelectrolyte-Assisted Noncovalent Functionalization of Carbon Nanotubes with Ordered Self-Assemblies of a Water-Soluble Porphyrin
Authors Suzana M. Andrade Perumal Raja Vipin K. Saini A. Viana Philippe Serp Sílvia M. B. Costa
Groups MPPM
Journal CHEMPHYSCHEM
Year 2012
Month November
Volume 13
Number 16
Pages 3622-3631
Abstract The self-assembly and induced supramolecular chirality of meso-tetrakis(4-sulfonatophenyl)porphyrin (TSPP) on both single-wall (SWCNT) and multiwall carbon nanotubes (MWCNT) are investigated. Under mild pH conditions (pH 3), TSPP forms aggregates when CNTs are dispersed in an aqueous solution containing positively charged polyelectrolytes such as poly-L-lysine (PLL) or poly(allylamine hydrochloride) (PAH). Evidence for the geometry of the porphyrin aggregates is obtained from absorption spectra, whereby the fingerprints of J- and H-aggregates are clearly seen only in the presence of smaller-diameter nanotubes. J-aggregates are better stabilized with PLL, whereas in the presence of PAH mainly H-aggregates prevail. Excited-state interactions within these nanohybrids are studied by steady-state and time-resolved fluorescence. The porphyrin emission intensity in the nanohybrid solution is significantly quenched compared to that of TSPP alone, and this implies strong electronic interaction between CNTs and porphyrin molecules. Fluorescence lifetime imaging microscopy (FLIM) further supports that porphyrin arrays are associated with the MWCNT sidewalls wrapped in PLL. In the case of the SWCNT hybrid, spherical structures associated with longer fluorescence lifetime appeared after one week, indicative of H-aggregates of TSPP. The latter are the result of pi pi stacking of porphyrin units on neighboring nanotubes facilitated by the strong tendency of these nanotubes to interact with each other. These results highlight the importance of optimum dimensions and surface-area architectures of CNTs in the control/stability of the porphyrin aggregates with promising properties for light harvesting.
DOI http://dx.doi.org/10.1002/cphc.201200428
ISBN
Publisher
Book Title
ISSN 1439-4235
EISSN 1439-7641
Conference Name
Bibtex ID ISI:000310602600008
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