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Updated: Jul 1, 2025

Imine Metathesis by Silica-Supported Catalysts Using the Methodology of Surface Organometallic Chemistry
Published on: October 18, 2019
The 2D-IR spectrum of hydrogen-bonded silanol groups in pyrogenic silica
1Central Laser Facility, Research Complex at Harwell, STFC Rutherford Appleton Laboratory, Harwell Science and Innovation Campus, Didcot OX11 0QX, United Kingdom.
Abstract:
Pyrogenic silica is a form of amorphous silica with a high surface area and a heterogeneous distribution of silanol hydroxyl terminations and defects. In this work, the interesting and unusual form of the hydroxyl-stretch 2D-IR spectrum of pyrogenic silica is presented and explored in the deuterated (deuteroxyl) form. Transition dipole couplings between hydrogen-bonded and non-hydrogen-bonded silanol groups give a distinct cross-peak in the 2D-IR spectrum, displaying interstate coherence oscillations during the 2D-IR experimental waiting time. The strong asymmetry about the diagonal is proposed to be the result of both the relatively small transition dipole coupling strength and the extreme differences in the width of the hydrogen-bonded and non-hydrogen-bonded silanol bands. The resulting interference of negative and positive cross-peaks has minimal intensity in the below-diagonal ω3 < ω1 region of the spectrum. An additional strong positive cross-peak is observed at a position in the 2D-IR spectrum inconsistent with transition dipole coupling. An assignment as a fifth order effect is proposed.
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