Thermodynamics of Quasi-Epitaxial Assembly of Fmn Around Various (n,m)-SWNTs

The helical assembly of self-organized flavin mononucleotide (FMN) around single-walled carbon nanotubes (SWNTs) presents among the highest organization order in nanotube surfactants.  In this contribution, we quantitatively analyze and model for the first time the cooperative hydrogen bonding of adjacent flavin moieties as well as the concentric π–π interactions between the isoalloxazine moieties and the underlying graphene lattice as a function of (n,m)-SWNT chirality.  For this we use dissociation thermodynamics of FMN-wrapped (n,m)-SWNTs dispersed in both H₂O and D₂O as a function of FMN concentration.  The binding strength of these FMN assemblies has been assessed in terms of ΔH, ΔS and ΔG.  Atomistic molecular simulations were used to modeled these data and link their dependence in terms of nanotube diameter (d_t) the chiral angle (j).  The findings of this study provide the first quantitative proof of the quasi-epitaxial assembly of FMN around various (n,m)-SWNTs.^[1]  This study demonstrates the architectural fidelity of FMN-wrapped SWNTs that closely emulates the dissociation mechanics of double-stranded DNA in its aqueous solutions.

^[1] Sharifi, R.; Samaraweera, M.; Gascón, J. A.; Papadimitrakopoulos, F.; J. Am. Chem. Soc., 2014, 136(20), 7452–7463.