Employment of the organic 2-(pyridin-4-yl)quinoline-4-carboxylic acid ligand with extended coordination capabilities leads to the formation of the onedimensional copper(II) coordination polymer catena-poly [[diaquacopper(II)under hydrothermal conditions. The ligand, isolated as its hydrochloride salt, namely, 4-(4-carboxyquinolin-2-yl)pyridinium chloride monohydrate, C 15 H 11 N 2 O 2 + ÁCl À ÁH 2 O, reveals a pseudosymmetry element (translation a/2) in its crystal structure. The additional pyridyl N atom, in comparison with the previously reported analogues with an arene ring instead of the pyridyl ring in the present ligand molecule, promotes the formation of a onedimensional coordination polymer, rather than discrete molecules. This polymer shows photoluminescent properties with bathochromic/hypsochromic shifts of the ligand absorption bands, leading to a single band at 479 nm. The Cu II ions are involved in weak antiferromagnetic interactions within dimeric units, as evidenced by SQUID magnetometry.# 2020 International Union of Crystallography ligand, reveals its photoluminescent and antiferromagnetic properties. The structure of the hydrochloride salt, namely, 4-(4-carboxyquinolin-2-yl)pyridinium chloride monohydrate, (II) (Scheme 2), was also determined.
Experimental
Synthesis and crystallizationDouble-distilled water was used and Cu(BF 4 ) 2 ÁH 2 O and 2-(pyridin-4-yl)quinoline-4-carboxylic acid (organic ligand) were purchased from Sigma-Aldrich and used as received. The organic ligand was characterized via TGA and NMR spectroscopy (see Figs. S2-S5 in the supporting information), as well as X-ray diffraction (see x2.5). 1 H NMR (500 MHz, methanol-d 4 ): 7.83 (ddd, 1H, J 1 = 8.6, J 2 = 6.8, J 3 = 1.3 Hz), 7.94 (ddd, 1H, J 1 = 8.5, J 2 = 6.8, J 3 = 1.4 Hz), 8.32 (ddd, 1H, J 1 = 8.5, J 2 = 1.3, J 3 = 0.6 Hz), 8.82 (s, 1H), 8.90 (ddd, 1H, J 1 = 8.6, J 2 = 1.4, J 3 = 0.6 Hz), 9.01 and 9.03 (AA 0 BB 0 system, 4H, J AB = 7.0 Hz). 13 C NMR (125 MHz,