Synthesis and Crystal Structure of New Lacunary Wells–Dawson with an Unprecedented Eu-Substituted Sandwiched Cluster

Abstract

A new red emitting sandwich-type phosphotungstate built on the lacunary Wells–Dawson polyanion [W17(PO4)1.75O52]10− and trivalent rare earth ion, $${\text{K}}_{ 8} \left[ {{\text{W}}_{ 3 5} {\text{Eu}}_{0. 5} \left( {{\text{PO}}_{ 4} } \right)_{ 1. 7 5} {\text{O}}_{ 10 5} } \right]_{2}$$ ·15·5H2O (1) has been synthesized and characterized by SEM-EDX, single crystal X-ray diffraction, and PL spectroscopy. It crystallizes in the monoclinic space group C2/c with unit cell dimensions a = 43.523(4) A, b = 12.3522(6) A, c = 29.4592(12) A, β = 100.933(6)°, Z = 2 and 15,549.8(16) A3. The crystal structure has been determined and refined to R1 and wR2 were 0.0682 and 0.1652 respectively. In this polyanion, two symmetrical EuIII cations sandwiched between C 2 symmetry related lacunary Wells–Dawson-like anions.