A Series of Metal–Organic Frameworks Constructed From a V‑shaped Tripodal Carboxylate Ligand: Syntheses, Structures, Photoluminescent, and Magnetic Properties

Six
novel complexes, namely, {[Zn1.5(L)­(bix)1.5(H2O)]·H2O}n (1), {[Co1.5(L)­(bix)1.5(H2O)]·H2O}n (2), {[Co3(L)2(4,4′-bpy)3]·5H2O}n (3), {[Cd3(L)2(4,4′-bpy)3]·4.5H2O}n (4), {[Cu3(L)2(4,4′-bpy)3]·3H2O}n (5), and {[Ni1.5(L)­(4,4′-bpy)1.5(H2O)3]·2H2O}n (6) have been synthesized by the hydrothermal reaction of 5-(4-carboxy-2-nitrophenoxy)­isophthalic
acid (H3L) with different transition metal ions in the
presence of ancillary ligands, 1,4-bis­(imidazol-1-ylmethyl)­benzene
(bix) and 4,4′-bipyridine (4,4′-bpy). Complexes 1 and 2 are isostructural, possessing a (3,8)-connected tfz-d type topology with the Schläfli symbol of {43}2{46·618·84}. The 3D structures of complexes 3–5 are very similar to complex 1 with only a little
difference of the H3L coordination motif in complexes 4 and 5. Meanwhile, we use 4,4′-bpy instead
of bix as the ancillary ligand in all three complexes. Complex 6 is a mixed one-dimensional chain and two-dimensional sheet
structure, which are further linked to each other in a three-dimensional
framework by H-bond interactions. All the complexes are characterized
by single crystal X-ray diffraction, IR spectroscopy, thermogravimetry
analysis, and elemental analysis. In addition, the luminescent properties
of complexes 1 and 4 are discussed, and
the magnetic properties of complexes 2 and 3 are also investigated.