Distinguishing the Silanol Groups in the Mesoporous Molecular Sieve MCM‐41

At least four types of silanol groups are present in MCM-41, a novel silicate with uniform mesopores, according to IR spectroscopy. Isolated silanol groups (type 1 in the picture on the right) and those involved in hydrogen bonds were distinguished by partial silylation with chlorotrimethylsilane (CTMS) and chlorotriphenylsilane (CTPS). Isolated silanol groups are accessible for both CTMS and the bulkier CTPS.