Microcrystallization of Benzene-d6 in Mesoporous Silica Revealed by 2H Solid-State Nuclear Magnetic Resonance

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Benzene-d6 confined in a mesoscopically organized, controlled, porous-glass mesocellular foam (MCF), with a pore diameter of 30 nm, is studied by low-temperature solid-state 2H nuclear magnetic resonance (2H NMR) spectroscopy in the temperature range of 90−180 K. The resulting spectra are compared to bulk benzene-d6 and benzene confined in a mesoporous silica (SBA-15). The comparison shows that the spectra in the MCF are the superposition of an amorphous surface phase and a crystalline inner bulk phase. For the inner crystalline phase, the activation energies coincide with that of bulk benzene. The pore volume and the filling factor indicate that approximately three molecular layers of benzene are present on the inner surfaces.