Three-Dimensional Metal Frameworks

Over the last few years, we have made a number of novel discoveries using reactive salt fluxes in the crystal growth experiment of mixed-metal oxides. The most important outcome that these salt-inclusion solids have demonstrated is the propensity for structure- directing effects of the employed salt. These hybrid solids have revealed fascinating solid-state structures ranging from nanoclusters to three-dimensional open frameworks of current interest. Solids featuring mag-... 

N. R. Organically templated three-dimensional open-framework metal selenites with a diamondoid network. J. Mater, Chem. 2003. 13, 1635-1638. (d) Behera, J. N. Ayi, A. A.. Rao. C. N. R. The First Organically Templated Open-Framework Metal Selenate with a Three-Dimensional Architecture. Chem. Commun. 2004, 456-457. 

B) Choudhury. A, Rao, C, N, R, Understanding the Building-Up Process of Three-Dimensional Open-Framework Metal Phosphates Acid Degradation of the 3D Structures to Lower Dimensional Structures, Chem, Commun. 2003, 366-367. 

Organically templated 3d-4f mixed metal sulfates of the formula [C2N2H10][La2M(H2O)2(SO4)6] (M = Co, Ni), have been recently synthesized by Clearfield et alP The three-dimensional anionic framework is formed by the bridging of La(lli) and divalent transition metal ions by the sulfate anions. 8-Membered ring tunnels run along the c-axis, which are occupied by the protonated organic cations. 

The structure of Prussian blue, which has been used as a pigment, and other similar materials such as Cu [Fen(CN)6](aq) or Mn3[Com(CN)6]2(aq) are based on a three-dimensional cubic framework with MA and MB atoms at the corners of a cube and with MA—N—C—MB links. There can be empty metal and CN sites depending on the stoichiometry, that is, on the valence of MA and MB. Water molecules can also be bound to Fera in Prussian blue as well as being interstitial as in zeolites. Reduction of Prussian blue gives Everitt s salt K2[FenFen(CN)6],... 

It is known that non-aqueous synthesis has been effectively applied in the preparation of various metal phosphates, including amine-containing aluminum, gallium, indium, zinc and cobalt phosphates with three-dimensional open-framework structures [17-24]. Moreover, phosphates with a layered or chain structure can been crystallized from non-aqueous media [25, 26]. Since the fluoride ions mineralizer was introduced into the synthesis of zirconium phosphates, several zirconium phosphate fluorides with novel structures have also been developed. 

It is not expected to be significant because of the three-dimensional metal oxide framework (see Figure 6.32), and not a layered structure as was always the case in the three previous examples. Yet the obvious anisotropy of the crystallite shapes (see the inset in Figure 6.31) suggests that the possibility of a complex preferred orientation cannot be completely excluded. 

C. Livage, N. Guillou, J. Chaigneau, P. Rabit, M. Drillon, and G. Ferey, A Three-dimensional Metal-organic Framework with an Unprecedented Octahedral Building Unit. Angew. Chem., Int. Ed., 2005, 44, 6488-6491. 

J. Sun, L. Weng, Y. Zhou, J. Chen, Z. Chen, Z. Liu, and D. Zhao, QMOF-1 and QMOF-2 Three-dimensional Metal-organic Open Frameworks with a Quartzlike Topology. Angew. Chem., Int. Ed., 2002, 41, 4471 1473. 

The contemporary interest in metal organophosphonate coordination chemistry has received considerable impetus from the applications of such materials as sorbents, catalysts and catalyst supports. The structural chemistry of the metal organophosphonate system is extremely rich " and is represented by mononuclear coordination complexes, molecular clusters, " one-dimensional materials, and layered phases. Extensive investigations have been reported on layered phosphonates of divalent, " trivalent, tetravalent, " and recently hexavalent elements. Several examples of three dimensional metal organophosphonate frameworks have also been described since the first report by Bujoli. " ... 

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