A new mono-thulium sandwiched arsenotungstate rare earth derivative K_8H_3[Tm(H_2O)_2(As_2W_(19)O_(67))(H_2O)]·15H_2O(1)has been synthesized by reaction of lacunary polyoxotungstrate precusor K_(14)[As_2W_(19)O_(67)(H_2O)]and TmCl3·7H2O in the presence of 2,6-pyridinedicarboxylic acid in water,which was characterized by IR spectrum,variable-temperature IR spectra,UV spectrum,TG analysis and X-ray diffraction.X-ray diffraction indicates that this compound crystallizes in the triclinic P-1space group with the...