Open Metal−Organic Framework Containing Cuprate Chains

A three-dimensional Cu(II) metal−organic framework, copper hydroxide p-pyridinecarboxylate hydrate, [Cu(OH)(C5H4NCO2)·H2O], was synthesized by hydrothermally reacting copper nitrate with p-pyridinecarboxylic acid. The
crystals were suitable for single-crystal X-ray diffraction analysis, which showed that the Cu(II) centers adopt a
slightly distorted square pyramidal geometry. They coordinate to both the pyridyl and carboxylate functionalities of
the pyridinecarboxylate bridging ligands. Infinite copper oxide chains run through the structure and are connected
by p-pyridinecarboxylate (p-PyC) ligands. Crystal data:  monoclinic, space group P21/n, a = 3.5521(2) Å, b =
15.8665(11) Å, c = 12.9977(9) Å, β = 95.285(2)°, and Z = 4. Thermogravimetric analysis (TGA) revealed that
the guest H2O molecules in the channels may be removed, and the material is stable to ca. 245 °C. Magnetic
measurements indicated the material has one-dimensional (1D) antiferromagnetic ordering within the Cu2+ chains
with a Néel temperature of ca. 51 K. Data fitting to the Bonner−Fisher model yielded a coupling constant, J, of
−7.3 cm-1 and g factor of 2.15. The Curie tail below 20 K is due to a small amount of paramagnetic impurities,
calculated to be ∼0.2% in concentration. Further characterization of crystallinity and morphology are discussed,
including powder X-ray diffraction (PXRD), elemental analysis, and optical microscopy.