Synthesis, crystal structures and luminescent properties of Cd(II)-arenesulfonate complexes containing N-heterocyclic auxiliaries

The reaction of 2-hydroxy-5-chlorobenzenesulfonic acid (H2L1), 2-hydroxy-5-chloro-1,3-benzenedisulfonic acid (H3L2), N-heterocyclic auxiliaries and CdX2 (X = NO3− and Ac−) salts leads to the formation of five new Cd(II) complexes, namely [Cd2(L1)2(phen)2] (1), [Cd2(L1)2(2,2′-bipy)2] (2), [Cd(HL1)2(2,2′-bipy)2] (3), [Cd1.5(L2)2(phen)2(H2O)]n·2nH2O (4) and [Cd(HL2)(2,2′-bipy)2]n·3nH2O (5), which have been characterized by elemental analysis, IR, TG, PL (photoluminescence), powder and single-crystal X-ray diffraction. Adjacent dinuclear units in complexes 1 and 2 are extended by extensive π⋯π and anion⋯π interactions to generate layer and chain motifs. Mononuclear units in complex 3 are interconnected by anion⋯π and hydrogen bonding interactions to form a 3-D supramolecular network which contains 1-D guest-free hydrophobic channels. In contrast, the Cd(II) cations in complexes 4 and 5 are joined by tri- and dianions to form chain structures, which are further extended by π⋯π interactions to give rise to 3-D supramolecular frameworks and chain structures. The different mono-, di- and trianions in the five complexes present diverse monodentate, μ2 (κ1O: κ1O′: κ2O″), μ3 (κ1O1: κ2O6: κ2O7) and μ2 (κ1O2: κ1O3) modes, respectively. Moreover, solid-state luminescent properties of the five complexes were also investigated at room temperature.

Five chelating N-heterocyclic-aided Cd(II) complexes based on two arenesulfonate ligands have been synthesized and characterized. The large conjugate system of the N-heterocyclic molecules is beneficial to the formation of extensive π⋯π and anion⋯π interactions, which extend the covalent structures into novel supramolecular networks.Figure optionsDownload as PowerPoint slide