Novel enantiomorphic Pb-coordination polymers dictated by the corresponding chiral ligands, [Pb((R,R)-TBA)(H2O)]·1.7H2O and [Pb((S,S)-TBA)(H2O)]·1.7H2O [TBA = 1,3,5-triazin-2(1H)-one-4,6-bis(alanyl)]

Abstract

New enantiomorphic Pb-based metal–organic coordination polymers, i.e., [Pb((R,R)-TBA)(H₂O)]·1.7H₂O (R1) and [Pb((S,S)-TBA)(H₂O)]·1.7H₂O (S1) (TBA = 1,3,5-triazin-2(1H)-one-4,6-bis(alanyl)), have been successfully synthesized through solvothermal reactions with the aid of carefully designed corresponding chiral ligands. Compounds R1 and S1 crystallizing in the chiral space group, P2₁2₁2₁, reveal infinite unidimensional (1D) chain structures consisting of highly distortive PbO₇ polyhedra with lone pairs. Owing to the multiple hydrogen bonding interactions with adjacent TBA ligands, the overall structures of R1 and S1 reveal three-dimensional frameworks containing 1D channels along the a-axis. The title compounds exhibit high water and chemical stabilities in a wide pH range. The reported complexes not only reveal second-harmonic generation signals originating from the macroscopic noncentrosymmetric structures, but also show a selective adsorption of anionic organic dyes via a host–guest hydrogen bonding interaction. A detailed adsorption study of the chiral Pb complexes towards a complete removal of organic dyes and the effect of pH and particle size on the adsorption are discussed.