Four new transition metal coordination polymers based on mixed 4-imidazole and carboxylate–sulfonate ligands: Syntheses, structures, and properties

Four new metal-organic coordination polymers [Zn(HL)(SIP)(H2O)]·2H2O (1), [Cd2(L)(H2L)(SIP)2] (2), [Cu2(L)2(SIP)(OH)]·2H2O (3) and [Ni3(L)4(SIP)2(H2O)4]·6.5H2O (4) were obtained by reactions of the different metal(II) salts with mixed ligands including sodium 5-sulfoisophthalate (Na3SIP) and 1,4-di(1H-imidazole-4-yl)benzene (L), respectively. All compounds were characterized by FT-IR spectroscopy, elemental analysis and single-crystal X-ray diffraction. The study indicates that different natures of metal ions play crucial roles in modulating the formation of the resulting frameworks. Compound 1 is a one-dimensional (1D) chain structure, and 2 is a (3, 8)-connected tfz-d three-dimensional (3D) net with a Point (Schlafli) symbol of (43)2(46·618·84). Complex 3 has (3, 5)-connecting node two-dimensional (2D) network with a Point (Schlafli) symbol of (42·67·8)(42·6) based on the {Cd2(OH)(SO3)}n2+ binuclear Cd(II) motif, while 4 is a rare 2D ​+ ​2D → 3D polycatenated framework resulting from two different kinds of (4, 4) 2D layers. The photoluminiscent properties as well as quantum yield (QY) and luminescence lifetime are also investigated for compounds 1 and 2 in the solid state.