Enantioselective Recognition and Separation by a Homochiral Porous Lamellar Solid Based on Unsymmetrical Schiff Base Metal Complexes

Abstract

Our Schiff has come in: A homochiral porous lamellar solid based on chiral unsymmetrical Schiff base metal complexes was assembled by using coordination and hydrogen bonds (see picture). The host features a flexible helical framework and chiral amphiphilic channel surfaces capable of multiple interactions with guest species.A homochiral lamellar supramolecular host system has been developed by treating 3-[(E)-{[(1R,2R)-2-aminocyclohexyl]imino}methyl]-4-hydroxybenzoic acid (H(2)L) with copper nitrate and characterized by a variety of techniques including microanalysis, IR spectroscopy, thermogravimetric analysis (TGA), circular dichroism (CD) spectroscopy, and powder and single-crystal X-ray diffraction. Tridentate Schiff base L ligands link adjacent metal centers to form 1D coordination polymeric chains using tridentate N(2)O donors and carboxylate groups, while interchain metal-oxygen and hydrogen-bonding interactions further link 1D polymeric chains to a porous lamellar solid. The host features a flexible helical framework for guest inclusions and chiral amphiphilic channel surfaces lined with amine hydrogen atoms and aliphatic groups capable of multiple interactions with guest species. It allows for the development of an efficient approach for highly enantioselective separation of racemic secondary alcohols by inclusion crystallization followed by distillation (>99.5 % ee). In addition, the host including different alcohols exhibits guest-responsive ferroelectric behavior.