Syntheses, structures and properties of four organic–inorganic hybrid nicotinate-bridging rare-earth-containing phosphotungstates

摘要

Four novel organic–inorganic hybrid nicotinate-bridging dimeric rare-earth (RE)-containing phosphotungstates [H2N(CH3)2]8[RE(H2O)(NA)(α-HPW11O39)]2·24H2O (RE?=?HoIIIfor1, ErIIIfor2,TbIIIfor3, DyIIIfor4; HNA?=?nicotinic acid) have been synthesized from the reaction of trivacant Keggin precursor Na9[α-PW9O34]?16H2O, RE(NO3)3·6H2O, HNA by employing dimethylamine hydrochloride as organic solubilizing agent in the conventional aqueous solution system, which have been further characterized by elemental analyses, IR spectra, thermogravimetric analyses and single-crystal X-ray diffraction. Structural analysis indicates that the hybrid dimeric {[RE(H2O)(NA)(α-HPW11O39)]2}8?polyoxoanion in1–4can be considered as two head-to-head mono-RE-containing Keggin [RE(H2O)(NA)(α-HPW11O39)]4?subunits bridged by two (η2,μ-1,1)-nicotinate linkers, which stands for the first organic–inorganic hybrid RE-containing phosphotungstates functionalized by nicotinate ligands. What's more, the solid-state photoluminescence properties and lifetime decay behaviors of1–4have been measured at room temperature and their photoluminescence spectra display the characteristic emission bands of corresponding trivalent RE cations.