A new mixed-valence Cu I /Cu II three-dimensional coordination polymer constructed with an N,O-donor ligand generated via solvothermal synthesis: structural features and magnetic properties.

A new mixed-valence Cu I /Cu II three-dimensional coordination polymer, poly[[diaquabis[μ 4 -2-(pyrazin-2-yl)quinoline-4-carboxylato]dicopper(I)copper(II)] bis(tetrafluoridoborate)], {[Cu 3 (C 14 H 8 N 3 O 2 ) 2 (H 2 O) 2 ](BF 4 ) 2 } n , was synthesized and characterized, with 2-(pyrazin-2-yl)quinoline-4-carboxylic acid being employed as a linker ligand. The ligand was isolated as its hydrochloride salt, 4-carboxy-2-(pyrazin-2-yl)quinolin-1-ium chloride dihydrate, C 14 H 10 N 3 O 2 + ·Cl - ·2H 2 O. The compounds show luminescence at 550 nm for the ligand and at 565 nm for the polymer at 297 K. The ligand structure was rationalized by means of quantum-chemical calculations, which led to a similar conformation to that determined from X-ray diffraction studies.