Second harmonic generation of a periodic mesoporous silica containing a triphenylpyrylium moiety

A periodic mesoporous SBA-15 silica containing 4,4-(N,N′-diallylaminophenyl)-2,6-diphenylpyrylium ion (BET surface area of 578 m2 g−1, pore size 5.2 nm) exhibits upon excitation at 1064 nm activity for second harmonic generation that is the double than that of an analogous MCM-41 material synthesized under basic conditions using cetyltrimethylammonium bromide. This fact has been explained as arising from the instability of pyrylium to basic pHs.