title: A Structural Model for a Self-Assembled Nanotube Provides Insight into Its Exciton Dynamics.
abstract: The design and synthesis of functional self-assembled nanostructures is frequently an empirical process fraught with critical knowledge gaps about atomic-level structure in these noncovalent systems. Here, we report a structural model for a semiconductor nanotube formed via the self-assembly of naphthalenediimide-lysine (NDI-Lys) building blocks determined using experimental13C-13C and13C-15N distance restraints from solid-state nuclear magnetic resonance supplemented by electron microscopy and X-ray powder diffraction data. The structural model reveals a two-dimensional-crystal-like architecture of stacked monolayer rings each containing ∼50 NDI-Lys molecules, with significant π-stacking interactions occurring both within the confines of the ring and along the long axis of the tube. Excited-state delocalization and energy transfer are simulated for the nanotube based on time-dependent density functional theory and an incoherent hopping model. Remarkably, these calculations reveal efficient energy migration from the excitonic bright state, which is in agreement with the rapid energy transfer within NDI-Lys nanotubes observed previously using fluorescence spectroscopy.
authors.affiliation: Department of Chemistry and Biochemistry, The Ohio State University , Columbus, Ohio 43210, United States.
authors.forename: Min
authors.initials: M
authors.lastname: Gao
authors.affiliation: Department of Chemistry and Biochemistry, The Ohio State University , Columbus, Ohio 43210, United States.
authors.forename: Subhradip
authors.initials: S
authors.lastname: Paul
authors.affiliation: Division of Computational Bioscience, Center for Information Technology, National Institutes of Health , Bethesda, Maryland 20892, United States.
authors.forename: Charles D
authors.initials: CD
authors.lastname: Schwieters
authors.affiliation: Department of Chemistry and Biochemistry, The Ohio State University , Columbus, Ohio 43210, United States.
authors.forename: Zhi-Qiang
authors.initials: ZQ
authors.lastname: You
authors.affiliation: Department of Chemistry and Biochemistry, The Ohio State University , Columbus, Ohio 43210, United States.
authors.forename: Hui
authors.initials: H
authors.lastname: Shao
authors.affiliation: Department of Chemistry and Biochemistry, The Ohio State University , Columbus, Ohio 43210, United States.
authors.forename: John M
authors.initials: JM
authors.lastname: Herbert
authors.affiliation: Department of Chemistry and Biochemistry, The Ohio State University , Columbus, Ohio 43210, United States.
authors.forename: Jon R
authors.initials: JR
authors.lastname: Parquette
authors.affiliation: Department of Chemistry and Biochemistry, The Ohio State University , Columbus, Ohio 43210, United States.
authors.forename: Christopher P
authors.initials: CP
authors.lastname: Jaroniec