Heterogeneous catalyst characterizationThe multi-step grafting method used to immobilize the unsymmetrical chiral complexonto silica was assessed by IR (Figs. 3, 4). Compared to pure silica, theaminopropylsilyl-functionalized silica (Fig. 3, curve b) gives a newband at 1,570 cm-1which can be attributed to the deformation vibration of N–H band of the amine groupwith three C–H stretchings at 2960, 2930 and 2855 cm-1 due to the alkyl groups(aminopropyl group). The reaction of 2,6-diformyl-4-tert-butylphenol with 3-aminopropylsilyl-functionalized silica (Fig. 3, curve c) shows the disappearance ofthe band at 1,570 cm-1 indicating the condensation of the amino group with onealdehyde group in 2,6-diformyl-4-tert-butylphenol to give a new band at 1,640 cm
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