Abstract
We explored the sensitivity of the 14N quadrupolar interaction toward the characterization of surfactant oxide interfaces. For the first time, experimental 14N NMR spectra are recorded, modeled, and compared for three different mesostructured silica (hexagonal p6mm, cubic Ia3d, and lamellar) templated by hexadecyltrimethylammonium cations (CTA+). Broad distributions in quadrupolar coupling constant CQ are obtained showing differences between phases. In parallel, quantum chemical calculations using the Born Oppenheimer molecular dynamics in combination with DFT have been successfully undertaken in a time scale of 25 32 ps to better understand the experimental results. From the two simulated models (CTA+ alone vs CTA+ in interaction with a D4R silicate oligomer), we evidenced the relative effect of fast conformational variations and of intermolecular interactions on the time-averaged 14N quadrupolar parameters. 14N relaxation and 13C CSA NMR data are also briefly presented and discussed. Our approach opens new directions for studying a wide range of mesostructured materials.