1-D, 2-D, and 3-D Organic–Inorganic Hybrids Assembled from Keggin-type Polyoxometalates and 3d-4f Heterometals

A series of organic–inorganic hybrid polyoxometalate derivatives {[Cu(en) 2 ] 1.5 [Cu(en)(2,2′-bipy)(H 2 O) n ]Ce[(α-PW 11 O 39 ) 2 ]} 6– [(Ln, n ) = (Ce III, 0) for 1, (Pr III, 1) for 2 )], {[Cu(en) 2 ] 2 (H 2 O)[Cu(en)(2,2′-bipy)]Ln[(α-HPW 11 O 39 ) 2 ]} 4– [Ln = Gd III for 3, Tb III for 4, Er III for 5 ] and {[Cu(en) 2 ] 1.5 [Cu(en)(2,2′-bipy)]Nd[(α-H 5 PW 11 O 39 ) 2 ]} 3– for 6 (2,2′-bipy =2,2′-bipyridine and en = ethylenediamine) have been successfully synthesized under hydrothermal conditions and further characterized by elemental analyses, inductively coupled plasma (ICP) analyses, X-ray powder diffraction (XRPD), IR spectra, UV spectra, electron paramagnetic resonance (EPR) spectra, thermogravimetric (TG) analyses, and single-crystal X-ray diffraction. The common features of 1 – 6 are that they all consist of sandwich-type [Ln(α-PW 11 O 39 ) 2 ] 11– polyoxoanions as the fundamental building blocks and copper coordination cations as bridges. 1 and 2 show the 1-D zigzag chains, and 3 – 5 exhibit the unprecedented 2-D structures built by [Ln(α-PW 11 O 39 ) 2 ] 11– polyoxoanions and [Cu(en) 2 ] 2+ and [Cu(en)(2,2′-bpy)] 2+ cations, whereas 6 displays the scarce 3-D framework with a (4 6 ·6 4 ) topology. As expected, 1 – 6 contain two types of organic ligands. Furthermore, the photocatalysis properties of rhodamine-B (RhB) upon a 500 W Hg lamp irradiation in the presence of 1, 2, 3, 4, 5, or 6 have been examined. The photoluminescence property of 4 has been investigated.