Lanthanide(III)−Cobalt(II) Heterometallic Coordination Polymers with Radical Adsorption Properties

Two new coordination polymers {[Ln2(PDA)6Co3(H2O)6]·xH2O}n [Ln
= Nd, x = 7 (1); Ln = Gd, x = 3.25 (2); H2PDA = pyridine-2,6-dicarboxylic acid] have been prepared under hydrothermal
conditions with Ln(NO3)3·6H2O, CoO, and H2PDA in a molar ratio
of 2:3:6. X-ray crystallographic analyses reveal that they crystallize
in the hexagonal group P6/mcc and exhibit a nanotubular 3D
framework. The adsorption experiment shows that 1 and 2 can
adsorb radicals, which is proven by electron paramagnetic
resonance spectra with the characteristic bands of the radicals at
g = 2.006 and 2.005, respectively.