Syntheses, structures and properties of a series of inorganic–organic hybrid copper–lanthanide heterometal comprising germanotungstates with mixed ligands

A series of inorganic–organic hybrid copper–lanthanide heterometal comprising germanotungstates were synthesized. Photoluminescence properties of the Eu-containing species were intensively investigated. [Display omitted] •Polyoxometalate-based copper–lanthanide heterometallic derivatives.•Inorganic–organic hybrid copper–lanthanide heterometal comprising germanotungstates.•The photoluminescence properties of the Eu3+ ions. The hydrothermal reaction of K8Na2[A-α-GeW9O34]·25H2O, Cu(CH3COO)2·H2O, Ln(NO3)·6H2O and ethylenediamine (en) has led to a series of inorganic–organic hybrid copper–lanthanide heterometal comprising germanotungstates (GTs) [Cu(en)2(H2O)]6[Ln(H2O)(CH3COO)(α-GeW11O39)]2·8H2O [Ln=Nd3+ (1), Sm3+ (2), Eu3+ (3), Gd3+ (4), Dy3+ (5), Ho3+ (6)], which have been characterized by elemental analyses, IR spectra, thermogravimetric (TG) analyses and single-crystal X-ray diffraction. Their common feature of 1–6 is that they all comprise a CH3COO-bridging mono-Ln substituted dimeric GT fragment [Ln(H2O)(CH3COO)(α-GeW11O39)]212− with six supporting [Cu(en)2(H2O)]2+ complex cations. To the best of our knowledge, such monovacant Keggin-type GTs containing both Cu–Ln heterometal centers and mixed en and acetate ligands are very rare. The luminescence properties and the lifetime decay behavior of the solid sample of 3 have been intensively investigated at room temperature.