Title

Rapid Molecular Motion Of Pyrene And Benzene Moieties Covalently Attached To Silica Surfaces

Abstract

Remarkably large rotational diffusion rates have been determined for silica-attached 1-pyrene at the solid/air interface through time-dependent fluorescence anisotropy measurements. Diffusion rates D∥ and D⊥ were determined to be 4 × 106 and 2 × 106 s-1, respectively, by treating the motion of the attached moiety as an oblate ellipsoid of rotation. 1-13 C NMR measurements on solid, silica-attached benzene-/-1-13C, acquired using conventional solution NMR methods, gave remarkable, high-resolution spectra. A lower limit for the rate of phenyl group motion was estimated to be 1.5 × 105 s-1, consistent with the fluorescence anisotropy data measured for silica-attached 1-pyrene. Molecular mechanics models for phenyl attached to representative silanol surfaces predict rotational barriers for phenyl rotations in the 2-5 kcal/mol range.

Publication Date

5-8-2003

Publication Title

Journal of Physical Chemistry A

Volume

107

Issue

18

Number of Pages

3450-3456

Document Type

Article

Personal Identifier

scopus

DOI Link

https://doi.org/10.1021/jp022045n

Socpus ID

0037995703 (Scopus)

Source API URL

https://api.elsevier.com/content/abstract/scopus_id/0037995703

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