Anion effect on surface density of silanolate groups in As-synthesized mesoporous silicas

Anions present in the synthesis gel (X = F-, Cl-, Br-, NO3-, and SO42-) partly remain in the channels of mesoporous templated silicas prepared in basic media. Their lyotropic character and their concentration control the silanolate group (=SiO-) density at the surfactant-inorganic interface through the electrical charge neutrality, implicating the positive charges of the templating self-assembled surfactants, Si. Accordingly, the well-accepted {S+ I-} generic pathway should be better referred as to {S+, mX(-), (1 - m)I-}.