The Synthesis Of Chiral Schiff Base Rare Earth Complexes In Catalysis

All experimental operations were carried out under the conditions of moisture and oxygen-free in nitrogen stream (99.99%). We prepared a kind of chiral C2-symmetric Schiff base H2L2- H2L6, and a Schiff base H2L1: N. N'-Bis(salicylidene)-1, 2-cyclohexanediamine which reacted with Ln(NO3)3 hydrate (Ln= La, Ce, Pr, Sm, Gd, Dy) to prepared six novel lanthanide(III) Schiff base complexes. The complexes have been characterized by Fourier -transform infrared(IR), Ultraviolet-visible(UV-vis), Elemental analyses, Thermal gravimetric analyses, Fluoresence measurements. The composition accorded with Ln(H2L1)(NO3)3 (MeOH)2 (Ln=La, Ce, Pr, Sm, Gd, Dy). The fluorescence spectra analysis showed that La3+ and Dy3+ enhanced the fluorescence intensity of the Schiff base compound, and La(III) and Dy(III) could be used as fluorescence probe for the Schiff base compounds.Asymmetric transfer hydrogenation of acetophenone was firstly conducted by using salt-free lanthanoid complexes of H2L2-H2L6, and the combination of SmCl3-(THF)4 and H2L3 was found to be the best catalyst system for asymmetric transfer hydrogenation of acetophenone. The composition of catalysis system is H2L3/SmCl3(THF)4/KOH, best ratio of Sub./Cat./KOH is 100:2:32, the appropriate temperature is 80 ℃ and reaction time is 12 hours. The best enantiosectivity (e.e. value) is 90%, and the best conversion is 87%.