Open framework solids

According to the experience of Guth et al. [20,21] in Mulhouse and ours in Versailles [12], one can define for F four main effects in the synthesis of open framework solids ... 

Following the successful introduction of transition metals into the zeolitic AlPOs and GaPOs and the parallel discovery of open framework solids with polyhedral coordinations larger than four, it was natural that workers in this field should attempt to synthesize open-framework transition metal phosphates. The presentation will follow a chronological sequence. 

A distinction should also be drawn between framework molecular sieves and the wealth of crystalline solids prepared in the presence of an organic species that becomes incorporated in voids within the structure but cannot be removed, thermally or otherwise, without structural collapse. These are better described as open framework solids. In practice the distinction is blurred and, although only materials that are thermally and hydrothermally robust are likely to be commercially exploited in traditional technologies, open framework solids containing organic species can possess properties that may make them suitable for more specialised use. 

Modelling the external surface structure of open framework solids is an area of much current interest. The surface structure is highly relevant in processes of crystal growth and in adsorption and catalysis. In the first process, the surface represents the site of attachment of species from solution, whereas in catalysis there is evidence that appreciable catalysis can take place at the external pore... 

These considerations are general to the synthesis of open framework solids. Details specific to particular chemical compositions are given below. By far the largest amount of synthetic work has been devoted to the aluminosilicates and other metallosilicates and silicas, which are synthesised hydrothermally at alkaline pHs (or pH 7 for fluoride syntheses). Phosphate-based solids have also received much attention and there is much current interest in inorganic-organic hybrid solids, such as carboxylates and phosphonates, which tend to have higher solubilities than silicates, and crystallise at more acidic pHs. 

Open-Framework Solids of the Vanadium Oxide Phosphate System 139... 

OPEN-FRAMEWORK SOLIDS OF THE VANADIUM OXIDE-PHOSPHATE SYSTEM... 

Chapter 4, by G. K. H. Shimizu et al., discusses work using metal-containing sulfonates and phosphonates as building blocks (linkers) to supramolecular networks. They describe the disruption of layered solids to form open-framework solids and examine the structure and dynamic behavior of these porous materials. 

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