Experimental and theoretical magneto-structural studies on the dicarboxylato-bridged nature of the dicopper(II)-based metal–organic frameworks

Two unprecedented metal–organic frameworks (MOFs) based on binuclear copper(II) second building units (SBUs), [Cu(INAIP)(dib)]·3.5H2O (1) and [Cu(INAIP)(4,4′-bpy)]·3H2O (2), [H2INAIP = 5-(isonicotinamido)isophthalic acid, dib = 1,4-di(1-imidazolyl)benzene and 4,4′-bpy = 4,4′-bipyridine] have been synthesized by mixed H2INAIP and rigid N-donor ligands with Cu(II) salt under hydrothermal conditions. Single crystal X-ray diffraction analysis revealed that the binuclear Cu(II) SBUs have similar coordination environments in complexes 1 and 2, however, 1 shows ferromagnetic interactions with J = 2.34 cm−1 while 2 exhibits antiferromagnetic interactions with J = −2.52 cm−1 within the Cu(II) dimer fitted by the spin Hamiltonian H = −JS1S2. Density functional theory (DFT) calculations were carried out using two simplified models based on their structures and the results revealed that the coupling constant with different basis sets matches well with the experimental J values of 1 and 2. This is an unusual example using theoretical calculations that evaluate the magnetic coupling interactions for the coordination polymers with binuclear subunits.

Two new Cu(II) coordination polymers with N-donor and carboxylate mixed ligands have been synthesized. And the magnetic property of the complexes containing binuclear copper(II) subunits is evaluated by experimental fitting and theoretical calculations.Figure optionsDownload as PowerPoint slideHighlights
► Coordination polymers with mixed 5-(isonicotinamido)isophthalate and rigid N-donor ligands.
► Complexes with 2D network and 3D framework structures.
► Experimental and theoretical magnetic study of the complexes.