Open-framework materials synthesis

Feng, P. Bu, X. Stucky, G. D, Designed assemblies in open-framework materials synthesis An interrupted sodalite and an expanded sodalite. Angew. Chem., Int. Ed. Engl. 199S, 34, 1745. 

Fig. 11. Synthesis of an open-framework material, 6 (structure of 6-Gd given in Figs. 12 and 13). Condensation of a bis(triester)hexavanadate unit with the pendant triester groups terminating in carboxylic acids, 5, with lanthanide ions form the open-framework catalytic materials.

The literature on inorganic open-framework materials abounds in the synthesis and characterization of metal silicates, phosphates and carboxylates. Most of these materials have an organic amine as the template. In the last few years, it has been shown that anions such as sulfate, selenite and selenate can also be employed to obtain organically templated open-framework materials. This tutorial review provides an up-to-date survey of organically templated metal sulfates, selenites and selenates, prepared under hydrothermal conditions. The discussion includes one-, two-, and three-dimensional structures of these materials, many of which possess open architectures, The article should be useful to practitioners of inorganic and materials chemistry, besides students and teachers. The article serves to demonstrate how most oxy-anions can be used to build complex structures with metal-oxygen polyhedra. 

Although isostructurality of components is often considered to be a very important factor in the synthesis of solid solutions, their formation via conventional solution-based methods is often hindered by the difference in solubility of individual components which leads to the preferential crystallization of separate components. The potential advantage of mechanochemistry for the construction of solid solutions of isostructural coordination polymers has been demonstrated by James and coworkers who constructed close-packed and open-framework materials by LAG reactions of rare earth metal carbonates and trimesic acid. In particular, LAG of each individual metal carbonate in the presence of water quantitatively yielded isostructural close-packed materials consisting of 1-D coordination polymers. In contrast, LAG with DMF resulted in the formation of isostructural lanthanide... 

The paradigm of how molecular-based Zintl compounds can be used to make porous materials has been demonstrated. The potential of Zintl phases to act as starting materials for the synthesis of a wide variety of open frameworks is enormous because of the broad diversity of such phases. Not only Zintl anions such as Eg and E4 (E = Ge, Si, Sn, Pb), Asy, E 14, Sby, and Inn composed of single elements but also binary and ternary ones, such as SnxE9 x" (E = Ge, Pb),... 

The discussion in the previous sections should suffice to indicate the importance of the transformations of molecular compounds to materials. Studies of such transformations are only making a beginning, and there appears to be a great future for such investigations, Thus, the recent synthesis of a sodalite-related structure from a molecular zinc phosphate is noteworthy, besides the transformation of the centrosymmetric, tetrameric, molecular alumino-phosphate to open-framework structures. Preliminary investigations53 have shown that interesting transformations also occur in metal carboxylates. Thus, molecular zinc oxalate monomers and dimers are found to transform to chain or three-dimensional structures on heating with piperazine in an aqueous medium, The chain structure transforms to a layer structure, We believe that it would... 

Lanthanide materials with potential applications as ion exchanger, moisture sensor, fluorescence material, and ion conductor, have attracted considerable research attentions [1-2]. Synthesis of open-framework lanthanide materials is of great interest because the interspaces of three-dimensional channels would be capable of enhancing some properties of this class of compounds, such as ion conductivity and ion exchange, and widening the application area as well [3, 4]. 

In this work, we focus on hydrothermal synthesis of open-framework cerium materials. By using fluoride ions mineralizer, two novel open-framework cerium materials, cerium phosphate fluoride (NH4)[Ce T2(P04)] (I), cerium oxyfluoride H25.5(NH4)io.5Ce9027Fi8 (II), have been prepared in presence of F ion. Both of them exhibited unique structural features, which is so different from traditionally porous materials, including zeolites and some metal phosphates. 

Mesoporous molecular sieves materials5-8 designated M41S (which include the MCM-41 class of materials) have made a further major impact on the area of synthesis of porous materials. A variety of open framework structures that are mesoporous have recently been reviewed by Thomas.9 Activated charcoal, MCM-41, mesoporous tungsten oxide, and substituted MCM-41 materials are mentioned. This article primarily emphasizes potential applications of such materials and possible mechanisms of reaction. The mesoporous sysems are compared briefly to microporous materials such as zeolites, ALPOs, MeALPOs and SAPOs. 

Whereas the development of crystalline, open-frameworks based upon silicates, phosphates and related materials has progressed at an ever increasing pace, the synthesis of simple binary oxides with periodic open stmctures has been less sue-... 

One remarkable aspect of many of these materials, as well as the hybrid metal oxide materials discussed in the next section, is that templates are rarely used in their synthesis. Instead, the open architectures are a consequence of interactions between the organic and inorganic groups. One notable exception is an open-framework zinc oxalate where the organic template, guanadinium, occupies a system of channels in the structure [134]. 

---