Hybrid Coordination Networks Constructed from ɛ‐Keggin‐Type Polyoxometalates and Rigid Imidazole‐Based Bridging Ligands as New Carriers for Noble‐Metal Catalysts |
| |
Authors: | Xiao‐Jian Yang Dr Meng Sun Prof Hong‐Ying Zang Dr Yuan‐Yuan Ma Dr Xiao‐Jia Feng Dr Hua‐Qiao Tan Dr Yong‐Hui Wang Prof Yang‐Guang Li |
| |
Institution: | 1. Key Laboratory of Polyoxometalate Science of Ministry of Education, Faculty of Chemistry, Northeast Normal University, Changchun, P.?R. China;2. College of Science, Shenyang Agricultural University, Shenyang, P.?R. China |
| |
Abstract: | Three hybrid coordination networks that were constructed from ?‐Keggin polyoxometalate building units and imidazole‐based bridging ligands were prepared under hydrothermal conditions, that is, H(Hbimb)2(bimb){Zn4PMoV8MoVI4O40}] ? 6 H2O ( 1 ), Zn(Hbimbp)(bimbp)3{Zn4PMoV8MoVI4O40}] ? DMF ? 3.5 H2O ( 2 ), and HZn2(timb)2(bimba)2Cl2{Zn4PMoV8MoVI4O40}] ? 7 H2O ( 3 ) (bimb=1,4‐bis(1‐imidazolyl)benzene, bimbp=4,4′‐bis(imidazolyl)biphenyl, timb=1,3,5‐tris(1‐imidazolyl)benzene, bimba=3,5‐bis(1‐imidazolyl)benzenamine). All three compounds were characterized by elemental analysis, IR spectroscopy, thermogravimetric analysis, and single‐crystal X‐ray diffraction. The mixed valence of the Mo centers was analyzed by XPS spectroscopy and bond‐valence sum calculations. In all three compounds, the ?‐Keggin polyoxometalate (POM) units acted as nodes that were connected by rigid imidazole‐based bridging ligands to form hybrid coordination networks. In compound 1 , 1D zigzag chains extended to form a 3D supramolecular architecture through intermolecular hydrogen‐bonding interactions. Compound 2 consisted of 2D curved sheets, whilst compound 3 contained chiral 2D networks. Because of the intrinsic reducing properties of ?‐Keggin POM species, noble‐metal nanoparticles were loaded onto these POM‐based coordination networks. Thus, compounds 1 – 3 were successfully loaded with Ag nanoparticles, and the corresponding composite materials exhibited high catalytic activities for the reduction of 4‐nitrophenol. |
| |
Keywords: | composite materials nanoparticles noble metals polyoxometalates reduction |
|
|