Effect of N-Donor Ancillary Ligands on Supramolecular Architectures of a Series of Zinc(II) and Cadmium(II) Complexes with Flexible Tricarboxylate

This work presents a systematic investigation on reactions of a flexible tricarboxylic acid with Zn(II), Cd(II) in the presence of varied N -donor ancillary ligands. Seven new metal−organic frameworks [Zn 3 (bta) 2 (bpy) 2 ] ( 1 ), [Zn 3 (bta) 2 (dpe) 2 ]·2H 2 O ( 2 ), [Zn 2 (OH)(bta)(bpe)]·2H 2 O ( 3 ), [Zn 2 (OH)(bta)(bpp)] ( 4 ), [Cd 2 (bta)(bpy) 2 (H 2 O)]ClO 4 ·H 2 O ( 5 ), [Cd 3 (bta) 2 (bpy) 2 ]·2H 2 O ( 6 ), and [Cd 3 (bta) 2 (H 2 O) 2 ] ( 7 ) [bta 3− = benzene-1,3,5-triacetate, bpy = 4,4′-bipyridine, dpe = 1,2-di(4-pyridyl)ethylene, bpe = 1,2-bis(4-pyridyl)ethane, and bpp = 1,3-bis(4-pyridyl)propane] have been obtained and characterized by single-crystal X-ray diffraction, IR, thermogravimetric and elemental analyses. Complexes 1 − 3, 5, and 6 are three-dimensional (3D) architectures containing infinite two-dimensional (2D) networks pillared by N -donor ligands, whereas 4 shows 2D network structure. Complex 3 has 2-fold interpenetration of 3D frameworks with 4.8 2 networks linked by bpe ligands, and 5 features an unusual 3D cationic supramolecular architecture. Complex 7 contains the Kagomé lattice inorganic layers, which are further linked by bta 3− ligands to form a 3D supramolecular architecture. The results showed that the structure and flexibility of the N -donor ancillary ligands have great influence on the structure of the complexes. The photoluminescence properties of 1 − 7 in the solid-state at room temperature have been studied.