Synthesis, structure and magnetic properties of four chiral Cu(II) complexes based on N-benzoyl-l-glutamic acid and different N-donor ancillary ligands

Abstract

Four new chiral Cu(II) complexes, namely [Cu2(bzgluO)2(2,2′-bipy)2]·7H2O (1), {[Cu(bzgluO)(2,4′-bipy)2(H2O)]·2H2O}n (2), [Cu2(bzgluO)2(4,4′-bipy)2]n (3), {[Cu2(bzgluO)2(bpe)2]·7H2O}n (4), have been synthesized in the presence of N-donor ancillary ligands [H2bzgluO=N-benzoyl-l-glutamic acid, 2,2′-bipy=2,2′-bipyridine, 2,4′-bipy=2,4′-bipyridine, 4,4′-bipy=4,4′-bipyridine, bpe=1,2-bis(4-pyridyl)ethane]. Their structures have been determined by single-crystal X-ray diffraction analyses and further characterized by elemental analyses, IR spectra, powder X-ray diffraction (PXRD), and thermogravimetric analyses (TGA). Complex 1 exhibits a 0D discrete unit, which is extended by the π…π stacking interactions to generate 2D supramolecular layers, a 1D infinite right-handed water chain exists in the 2D layers. Complexes 2–4 are coordination polymeric networks. Complex 2 displays a 1D chain structure and is extended by the hydrogen-bonding to generate 2D supramolecular layers. Complex 3 is a 3D pillared layered framework by linking a 2D [Cu(bzgluO)]∞ layer with 4,4′-bipy molecules. Complex 4 comprises 3D networks containing small voids occupied by water molecules. The structural difference indicates that the effect of N-donor ancillary ligand is critical in construction of polymeric arrangement. This work will provide a favorable idea for us to construct the higher dimensionality available metal–organic framework. In addition, the solid-state circular dichroism (CD) and the magnetic properties of the complexes were investigated.