A pair of novel Zn(ii) enantiomeric coordination polymers based on a chiral multicarboxylate ligand: synthesis, crystal structures and molecular recognition properties

Abstract

A pair of Zn(II) enantiomeric coordination polymers, 1-R and 1-S, namely, [Zn₄((R)-H₃L)₂(OH)₂(H₂O)₂]·3H₂O {H₃L= (R)- or (S)-5-(1-carboxyethoxymethyl)-isophthalic acid}, were synthesized via solvothermal reactions. Their structures were determined by single-crystal X-ray diffraction analysis and further characterized by IR spectra, elemental analyses, thermogravimetric analysis (TGA), solid-state circular dichroism (CD) and powder X-ray diffraction (PXRD). The pair of enantiomers crystallized in the same chiral space group, featuring a 3,6-c net and kgd topological type structure with a point symbol of (4³)₂(4⁶·6⁶·8³). Their CD spectra exhibit obvious positive or negative Cotton effects, indicating their homochirality. 1-R and 1-S also proved to be second-harmonic generation (SHG) active. Moreover, their fluorescent selective recognition towards nitro aromatic compounds and metal cations were also investigated.