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Investigating Structural Alterations in Pyrogallol[4]arene‐Pyrene Nanotubular Frameworks
Author(s) -
Kumari Harshita,
Kline Steven R.,
Wycoff Wei G.,
Atwood Jerry L.
Publication year - 2012
Publication title -
small
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.785
H-Index - 236
eISSN - 1613-6829
pISSN - 1613-6810
DOI - 10.1002/smll.201201384
Subject(s) - pyrogallol , pyrene , acetone , chemistry , neutron scattering , diffusion , hydrogen bond , solvent , crystallography , chemical engineering , organic chemistry , molecule , scattering , thermodynamics , physics , optics , engineering
Small‐angle neutron scattering (SANS) and diffusion NMR studies are performed to investigate the stability and geometry of hydrogen‐bonded pyrene‐guest‐containing C ‐hexylpyrogallol[4]arene (PgC 6 ‐pyrene) nanotubular frameworks in solution. In the solid state, hydrogen‐bonded pyrogallol[4]arene tubes are formed; however, the scattering data for PgC 6 ‐pyrene assemblies in acetone are best modeled as dimeric spheres of PgC 6 with no pyrene guest. The result of diffusion NMR study also indicates the rearrangement of tubular entity into spherical framework in acetone. This is the first example of structural transformation of pyrogallol[4]arene nanotubes (guest‐exo) in solution. Individual hydrogen‐bonded spheres of PgC 6 exhibits a uniform radius of ca. 8.6 Å and a diffusion coefficient of 9.12 × 10 −10 m 2 s −1 in acetone. The diffusion NMR measurements further gave, for the first time, insights into how the type of solvent (acetone vs. methanol vs. acetontitrile/D 2 O) governs the structural differences in these nanoassemblies. Solution‐phase structural alteration observed for PgC 6 ‐pyrene gives evidence of enhanced stability of pyrogallol[4]arene nanocapsules over nanotubes.