Yanzhou Li

Recent progress in metal-functionalized germanotungstates: from structures to properties

As an important ramification of polyoxometalates, germanotungstate (GT) chemistry has gradually developed as a new research focus and a challenging area, and has made great progress in the past decade due to a wide range of potential applications in various areas such as catalysis, magnetism, photochemistry and materials science. In this review, we mainly focus on three categories of metal-functionalized GTs: transition metal (TM)-substituted GTs (TMSGTs), rare earth (RE)-substituted GTs (RESGTs) and GT-based TM–RE heterometallic derivatives (GTTRHDs). We discuss their synthetic strategies, structural features and some properties involving magnetism, electrochemistry and catalysis. Finally, some perspectives on this field are also provided and some possible directions for future work are outlined.

Hydrothermal Synthesis and Structural Characterization of a 1-D Inorganic-Organic Composite Tetra-Nickel Substituted Sandwich-Type Phosphotungstate

A 1-D inorganic-organic composite tetra-nickel substituted sandwich-type phosphotungstate [Ni(H2O)(en)2]2[Ni(en)2]3 [Ni4(H2O)2(α-B-HPW9O34)2]·12H2O (1) (en = ethylenediamine) has been hydrothermally synthesized and structurally characterized. X-ray diffraction indicates that the molecular fragment of 1 consists of a classical tetra-NiII sandwiched polyoxoanion [Ni4(H2O)2(α-B-HPW9O34)2]10− and two [Ni(H2O)(en)2]2+ cations, three [Ni(en)2]2+ cations, and 12 lattice water molecules. The most remarkable feature is that each molecular fragment is connected with each other by [Ni(en)2]2+ bridges constructing the 1-D chain structure. The thermogravimetric curve of 1 shows three steps of weight loss. Magnetic susceptibility measurements demonstrate that 1 indicates the ferromagnetic couplings within nickel centers.

Hydrothermal synthesis and structural characterization of an organic–inorganic hybrid sandwich-type tungstoantimonate [Cu(en){sub 2}(H{sub 2}O)]{sub 4}[Cu(en){sub 2}(H{sub 2}O){sub 2}][Cu{sub 2}Na{sub 4}(α-SbW{sub 9}O{sub 33}){sub 2}]·6H{sub 2}O

Abstract An organic–inorganic hybrid sandwich-type tungstoantimonate [Cu(en) 2 (H 2 O)] 4 [Cu(en) 2 (H 2 O) 2 ][Cu 2 Na 4 ( α -SbW 9 O 33 ) 2 ]·6H 2 O ( 1 ) has been synthesized by reaction of Sb 2 O 3 , Na 2 WO 4 ·2H 2 O, CuCl 2 ·2H 2 O with en (en=ethanediamine) under hydrothermal conditions and structurally characterized by elemental analysis, inductively coupled plasma atomic emission spectrometry, IR spectrum and single-crystal X-ray diffraction. 1 displays a centric dimeric structure formed by two equivalent trivacant Keggin [ α -SbW 9 O 33 ] 9− subunits sandwiching a hexagonal {Cu 2 Na 4 } cluster. Moreover, those related hexagonal hexa-metal cluster sandwiched tungstoantimonates have been also summarized and compared. The variable-temperature magnetic measurements of 1 exhibit the weak ferromagnetic exchange interactions within the hexagonal {Cu 2 Na 4 } cluster mediated by the oxygen bridges.

2-D and 3-D phosphotungstate-based TM-Ln heterometallic derivatives constructed from dimeric [Ln({alpha}-PW{sub 11}O{sub 39}){sub 2}]{sup 11-} fragments and copper-organic complex linkers

Three organic-inorganic hybrid TM-Ln heterometallic phosphotungstates [Cu(dap){sub 2}(H{sub 2}O)][Cu(dap){sub 2}]{sub 3.5}[La({alpha}-HPW{sub 11}O{sub 39}){sub 2}]{center_dot}6H{sub 2}O (1) [Cu(dap){sub 2}(H{sub 2}O)]{sub 0.5}[Cu(dap){sub 2}]{sub 4}[Nd({alpha}-HPW{sub 11}O{sub 39}){sub 2}]{center_dot}4H{sub 2}O (2) and [Cu(dap){sub 2}(H{sub 2}O)]{sub 2}[Cu(dap){sub 2}]{sub 3.5}[Eu({alpha}-PW{sub 11}O{sub 39}){sub 2}]{center_dot}6H{sub 2}O (3) (dap=1,2-diaminopropane) have been hydrothermally synthesized and structurally characterized by elemental analyses, IR spectra, optical diffuse reflectance spectra, powder X-ray diffraction (PXRD), thermogravimetric (TG) analyses and single-crystal X-ray diffraction. Their common features are that 1-3 all consist of asymmetric sandwich-type subunits [Ln({alpha}-PW{sub 11}O{sub 39}){sub 2}]{sup 11-} and [Cu(dap){sub 2}]{sup 2+} bridges. Both 1 and 2 display the 2-D (4,4)-topological sheets whereas 3 exhibits the 3-D 5-connected (4{sup 6}{center_dot}6{sup 4}) topological framework. The magnetic properties of 2 and 3 and the luminescence performance of 3 have been measured. - Graphical Abstract: Three TM-Ln heterometallic phosphotungstates 1-3 have been synthesized and characterized by elemental analyses, IR spectra, optical diffuse reflectance spectra, X-ray diffraction, thermogravimetric analyses magnetic susceptibility and luminescent properties. Highlights: Black-Right-Pointing-Pointer Cu{sup II}-Ln{sup III} heterometallic polyoxometalates. Black-Right-Pointing-Pointer 2-D and 3-D organic-inorganic hybrid phosphotungstates. Black-Right-Pointing-Pointer 2-D and 3-D structures consisting of Cu{sup II}-Ln{sup III} heterometals.