title: Thermodynamics of the quasi-epitaxial flavin assembly around various-chirality carbon nanotubes.
abstract: Establishing methods to accurately assess and model the binding strength of surfactants around a given-chirality single-walled carbon nanotube (SWNT) are crucial for selective enrichment, targeted functionalization, and spectrally sharp nanodevices. Unlike surfactant exchange, which is subject to interferences from the second surfactant, we herein introduce a thermal dissociation method based on reversible H(+)/O2 doping to determine SWNT/surfactant thermodynamic stability values with greater fidelity. Thermodynamic values were reproduced using molecular mechanics augmented by ab initio calculations in order to better assess π-π interactions. This afforded detailed quantification of the flavin binding strength in terms of π-π stacking (55-58%), with the remaining portion roughly split 3:1 between electrostatic plus van der Waals flavin mononucleotide (FMN) interdigitation and H-bonding interactions, respectively. Quasi-epitaxial π-π alignment between the near-armchair FMN helix and the underlying nanotube lattice plays a crucial role in stabilizing these assemblies. The close resemblance of the thermal dissociation method to helix-coil and ligand-binding transitions of DNA opens up a unique insight into the molecular engineering of self-organizing surfactants around various-chirality nanotubes.
authors.affiliation: Nanomaterials Optoelectronics Laboratory (NOEL), Polymer Program, Institute of Materials Science and ‡Department of Chemistry, University of Connecticut , Storrs, Connecticut 06269-3136, United States.
authors.forename: Roholah
authors.initials: R
authors.lastname: Sharifi
authors.forename: Milinda
authors.initials: M
authors.lastname: Samaraweera
authors.forename: José A
authors.initials: JA
authors.lastname: Gascón
authors.forename: Fotios
authors.initials: F
authors.lastname: Papadimitrakopoulos
mesh_terms: D004138:Dinitrocresols / Q000737:chemistry*; D008968:Molecular Conformation; D056004:Molecular Dynamics Simulation; D037742:Nanotubes, Carbon / Q000737:chemistry*; D011789:Quantum Theory; D055672:Static Electricity; D013816:Thermodynamics
chemical_list: D004138:Dinitrocresols; D037742:Nanotubes, Carbon; C024132:4,6-dinitro-o-cresol