Syntheses, topological analyses and photoelectric properties of Ag(I)/Cu(I) metal-organic frameworks based on a tetradentate imidazolate ligand

A new tetradentate imidazolate ligand 1,1′,1″,1′′′-(2,2′,4,4′,6,6′-hexamethylbiphenyl-3,3′,5,5′-tetrayl)tetrakis(methylene)(1H-imidazole) (L) and four Ag(I)/Cu(I) coordination polymers, namely [(MCN)3L]n (1: M=Ag; 2: M=Cu), and [(MSCN)2L]n (3: M=Ag; 4: M=Cu) are described. All four new coordination polymers were fully characterized by infrared spectroscopy, elemental analysis and single-crystal X-ray diffraction. Compound 1 features a 3D supramolecular framework constructed by 1D chains through inter-chain Ag–N(CN) and inter-layer Ag–N(L) weak interactions with an uninodal 66 topology. Complex 2 presents a 3D framework characterized by a tetranodal (3,4)-connected (3·4·5·102·11)(3·4·5·6·7·9)(3·6·7)(6·102) topology. Complexes 3 and 4 are isostructural, and both have a 3D network of trinodal 4-connected (4·85)2(42·82·102)(42·84)2 topology. The luminescent properties for these compounds in the solid state as well as the possible ferroelectric behavior of 1 are discussed.