Synthesis, Structures, Electrochemical Analysis, and Luminescence Properties of Four Supramolecular Complexes Based on Quinoline-2-carboxylic Acid

Four new coordination complexes with quinoline-2-carboxylate ion (quin-2-c),[Mn(quin-2-c)(H2O)(3)Cl]center dot H2O(1), Cd(quin-2-c)(2)(H2O)(2)(2), Co(quin-2-c)(2)(H2O)(2) (3), Ni(quin-2-c)(2)(H2O)(2) (4)(quin-2-c = quinoline-2-carboxylic acid ion), have been synthesized and characterized by IR and single crystal X-ray diffraction. Complex 1 and 3 forms 3-D structure vis hydrogen bonds and pi-pi contacts, and Complex 2 forms 2-D layers vis hydrogen bonds and pi-pi contacts. Complex 4 takes a 2-D hydrogen-bonding net structure. Complex 3 and 4 with the same coordination structure display different hydrogen bonds, which may suggest some connection between the radii of the metal ions and hydrogen bonds. Furthermore, the luminescence properties and electrochemical properties of 1 to 4 were studied. All this work may offer guidance for design of biological labels based on quinoline-2-carboxylic acid.