Novel polyoxometalate hybrids consisting of copper-lanthanide heterometallic/lanthanide germanotungstate fragments

摘要

Three organic-inorganic hybrid copper-lanthanide heterometallic germanotungstates, {[Cu(en) _2(H _2O)] [Cu _3Eu(en) _3(OH) _3(H _2O) _2](α-GeW _(11)O _(39))} _2·11H _2O (1), {[Cu(en) _2(H _2O)][Cu _3Tb(en) _3(OH) _3(H _2O) _2](α-GeW _(11)O _(39))} 2·11H _2O (2) and {[Cu(en) _2(H _2O)][Cu _3Dy(en) _3(OH) _3(H _2O) _2](α-GeW _(11)O _(39))} 2·10H _2O (3) and three polyoxometalate hybrids built by lanthanide-containing germanotungstates and copper-ethylendiamine complexes, Na _2H _6[Cu(en) _2(H _2O)] _8{Cu(en) _2[La(α-GeW _(11)O _(39)) _2] _2}·18H _2O (4), K _4H _2[Cu(en) _2(H _2O) _2] _5[Cu(en) _2(H _2O)] 2[Cu(en) _2] _2{Cu(en) _2[Pr(α- GeW _(11)O _(39)) _2] _2}·16H _2O (5) and KNa _2H _7[enH _2] _3[Cu(en) _2(H _2O)] _2[Cu(en) _2] _2{Cu(en) _2[Er(α-GeW _(11)O _(39)) _2] _2}·15H _2O (6) (en = ethylenediamine) have been hydrothermally synthesized and structurally characterized by elemental analyses, inductively coupled plasma atomic emission spectrometry (ICP-AES) analyses, IR spectra, powder X-ray diffraction (PXRD), X-ray photoelectron spectroscopy (XPS) and single-crystal X-ray diffraction. 1-3 are essentially isomorphous and their main skeletons display the interesting dimeric motif {[Cu _3Ln(en) 3(OH) _3(H _2O) _2](α-GeW _(11)O _(39))} _2 ~(4-), which is constructed from two {Cu _3LnO _4} cubane anchored monovacant [α-GeW _(11)O _(39)] ~(8-) fragments through two W-O-Ln-O-W linkers. The primary backbones of 4-6 exhibit the tetrameric architecture {Cu(en) _2[Ln(α-GeW _(11)O _(39)) _2] _2} ~(24-) built by two 1:2-type [Ln(α-GeW _(11)O _(39)) _2] ~(13-) moieties and one [Cu(en) _2] ~(2+) bridge, albeit they are not isostructural. To our knowledge, 1-6 are rare polyoxometalate derivatives consisting of copper-lanthanide heterometallic/lanthanide germanotungstate fragments. 1 exhibits antiferromagnetic coupling interactions within the {Cu _3EuO _4} cubane units, while 2 and 3 display dominant ferromagnetic interactions between the Tb ~(III)/Dy ~(III) and Cu ~(II) cations. The room-temperature solid-state photoluminescence properties of 1-3 have been investigated.