Multilple host-guest interactions in heterogeneous vanadium catalysts: Inorganic nanosheets modified alpha-amino acids as ligands

作者：Liu, Hui; Zhao, Liwei; Wang, Jiuzhao; He, Jing^*

来源：Journal of Catalysis, 2013, 298: 70-76.

DOI：10.1016/j.jcat.2012.11.022

• Host-guest interaction
• Inorganic nanosheet
• alpha-Amino acid
• Supramolecular catalysts

The catalysts using layered double hydroxide (LDH) nanosheet-modified alpha-amino acid anions as ligands has been proved to be easily recycled in vanadium-catalyzed asymmetric epoxidation of cinnamyl alcohol with the enantioselectivity well preserved and the yield only slightly reduced. The alpha-amino acids employed here include L-glutamate, L-alanine, and L-serine, which are anchored to LDH layers through monodentate electrostatic interactions in the ascending intensity while coordinated with vanadium center in the coordinating intensity of L-glutamate > L-serine > L-alanine. The stronger coordination with alpha-amino acid anion caused the vanadium center to be leached independently in less percentage, while the leaching of alpha-amino acid anion depends on the dual host-guest interactions. In nanosheet-modified L-glutamate system, all of the vanadium centers leached together with L-glutamate, but in nanosheet-modified L-alanine system, all of the vanadium centers leached independently. The electrostatic interaction of brucite-like layer with L-serine is stronger than with L-alanine, yet the stronger coordination of L-serine to vanadium caused more L-serine to be leached. The weakest electrostatic interactions between intercalated L-glutamate and LDH layer result in the visible loss of L-glutamate in the vanadium/LDH nanosheet-modified L-glutamate system, but the V-glutamate species leached into the solution was catalytically active in the epoxidation, compensating for the activity loss in the recycling experiments in spite of the higher L-glutamate leaching.

• 出版日期2013-2
• 单位北京化工大学; 化工资源有效利用国家重点实验室