Controlled Synthesis of Supramolecular Architectures of Homo- and Heterometallic Complexes by Programmable Self-Assembly

The reaction of ligand (H2L) named 3-(3,5-dimethyl-1H-pyrazol-4-yl)pentane-2,4-dione and Cu(NO3)(2) produces two types of supramolecular homometallic complexes well-controlled by stepwise deprotonation. With lower NaHCO3 concentrations as the base, the product [Cu(HL)(2)](4) (1) exhibits a two-dimensional (2D) rhombus with Cu/(HL) = 1:2. When NaHCO3 is further employed on complex 1, however, the product [Cu(HL)(L)](n) (2) with Cu/(HL)/(L) = 1:1:1 displays a zigzag one-dimensional (1D) chain. The ditopic ligand is used also for the programmable self-assembly of a zero-dimensional (0D) mononuclear complex [Fe(HL)(3)] (3) and one-dimensional (1D) heterometallic multinuclear complex [AgFe(HL)(3)(NO3)(n) (4). Complex 3 readily forms upon reaction of H2L with Fe(NO3)(3) and NaHCO3 as the base. The reaction of 3 with the second metal salt yielded the complex 4 with a porous ladder structure. Complexes 1, 2, 3, and 4 were investigated by a combination of X-ray crystallography, powder X-ray diffraction, elemental analysis, thermogravimetric analysis, and infrared spectroscopy. Magnetic susceptibilities of these complexes 1 and 2 have been also measured by SQUID techniques.