Flavin-derived Self-organization and Chirality Separation of Single-walled Carbon Nanotubes
ProQuest, 2008 - 150 pages
Chapter 4 revisits the surfactant amine-assisted semiconducting ( sem-) SWNTs separation in THF media. For this, we synthesized an asymmetric diacetylenic surfactant amine(57ECA), in which adequate chemical anisotropy was generated along its tail to probe the molecular dynamics in the presence and absence of nanotubes via NMR. This surfactant can simulate the similar sem-SWNTs separation, like ODA. This study suggests that the surfactant amine head is firmly immobilized onto the nanotube surface together with acidic water, while the aliphatic tail progressively gains larger mobility as it gets farther from the SWNT. The spectroscopic results indicate that the sem-enriched sample is populated mainly from small nanotube bundles containing three SWNTs. Molecular simulations in conjunction with previously determined HNO3/H2SO4 oxidation depths for met- and sem-SWNTs indicate that the strong pinning of the amine surfactants on the sem-enriched SWNTs bundles is a result of a well-ordered arrangement of amine salts separated with a monomolecular layer of H2O molecules. Such continuous 2D arrangement of hydrated amine salts can be attained from a specific type and diameter nanotubes, which provides the necessary surfactant stability for effective THF dispersion and subsequent enrichment.
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SYNTHESIS AND REDOX BEHAVIOR OF FLAVIN
CHIRALITY SELECTION THROUGH HELICAL SELF
ENRICHMENT MECHANISM OF SEMICONDUCTING
13C NMR a-SWNTs acid addition aqueous Calcd carbon nanotubes carboxylic Chem chemical shifts chiral chiral angle cofactor Compound 9 covalent attachment diacetylenic diameter dt dispersed dithionite Dresselhaus electron enrichment ethanol excitonic Figure flavin derivatives flavin moiety flavin mononucleotide flavin mononucleotide FMN FMN-dispersed function FWHM graphene H NMR helical HHCar HiPco HiPco sample HiPco SWNTs HRTEM illustrates indicate inset interactions isoalloxazine moieties isoalloxazine ring mef-SWNTs mixture mmol moiety molecular Nano Lett neat 57ECA NMR spectra NMR tube oxidation Papadimitrakopoulos peak phosphate photoluminescence Phys physisorbed PL intensity PLE map presence of SWNTs proton pyridine redox redshift respectively room temperature Scheme SDBS SDBS concentration sem-SWNTs semiconducting sidewalls SINGLE-WALLED CARBON NANOTUBES Smalley sodium dodecyl sodium dodecyl sulfate solution sonication spectroscopy Strano supernatant surfactant surfactant amine suspension SWNT forests SWNTs THF-ds transitions UV-Vis absorption UV-Vis-NIR wavelength was 350