Photoluminescence Properties of Two Closely Related Isostructural Series Based on Anderson-Evans Cluster Coordinated With Lanthanides [Ln(HO){X(OH)MoO}]•yHO, X = Al, Cr.

The paper describes synthesis and structural characterization of the whole series of two closely related lanthanide coordinated chromium or aluminum hexamolybdates (Anderson-Evans cluster) including twelve new members hitherto unreported: [Ln(HO){X(OH)MoO}]·4HO and [Ln(HO){X(OH)MoO}Ln(HO)]{X(OH)MoO}·16HO where X = Al or Cr and Ln = La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, and Y. Crystal structures of all the solids were established by powder and single crystal X-ray diffraction techniques. The two series are dictated by a different aggregation of the same set of molecular species: Lighter lanthanides favor coordination interaction between lanthanide ions and molybdate cluster forming 1D chains (Series I) while the heavier lanthanides result in the stacking of a cation, a pair of lanthanide hydrates coordinating to the cluster, and an anion, the discrete cluster is further stabilized through a large number of water molecules (Series II).