Abstract: We have studied diastereomeric chiral interactions within sols, gels and xerogels of silicas and derivatized silicas (20% phenylated and 10% octadecylated silicas) doped with the chiral surfactant (–)-N-dodecyl-N-methylephedrinium bromide (DMB). Two spectral methods – new in the context of chiral sol–gel materials – have been used for that purpose. In the first method, we were able to detect the diastereomeric interactions between DMB and each of the pure enantiomers of co-doped 1,1-binaphthyl-2,2-diyl hydrogenphosphate using 31P-NMR spectroscopy. In the second method, we were able to obtain an induced circular dichroism (ICD) signal from the achiral dye Congo Red co-doped with DMB. NMR and ICD are complementary in understanding the way in which the chiral surfactant creates chiral environments inside the sol–gel materials. In particular, we provide ICD evidence that the silica network itself becomes chiral due to the entrapment of the chiral surfactant.
Template and target information: 1,1-binaphthyl-2,2-diyl hydrogenphosphate, Congo red