Pillared layer structures

Diphosphonates of types (5.375b-d) lead to somewhat tighter-bound ionic layer structures since the inter-layer van der Waals bonding, which is present in (5.375a), is absent [109-114], 

Another type of pillared structure is represented by (5.375c) where one end of the pillar is -POf and the other is -COO. This occurs in Zn3(03PCH2CH2COO)2. 

Dehydration of Si(HP04)2 -H20 produces a form of Si2P207 with a layer structure related to that of Zr(HP04)2 H2O. This structure contains inter-layer P-O-P pillars as shown below. 

The lamellar sheet-like structure of amine-intercalated Zr(HP04)2 can be delaminated to give thin films of pellicular hydrated zirconium phosphate. These will adhere to flat surfaces and are stable to solvents and temperatures up to 300-400°C. Pellicular forms are good proton conductors and have potential applications in ion exchange and chromatography. 

FIGURE 5.52 Layer structures of Zr(03P CgH QH ). (a) Unmodified and (b) modified by ZrfOjPOHij showing cavity formed. 

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Mitchell IV (1990) Pillared layered structures current trends and applications. Elsevier Applied Science, London... 

According to the results in Table 1, SCD creates larger surface area at the expense of substantial loss in the surface area and volume of micropores. Sample SCD has a quite low apparent density, compared with the sample dried in air. Evidently, SCD treatment results in a significant change in the framework of the sample. The pillared layered structure which is... 

E. Gutierrez and E. Ruiz-Hitzkv. Pillared Layered Structures Current Trends and Applications. I.V. Mitchell (Ed.), Elsevier Appl. Sci., London (1990), 199-208. 

Amino-carboxylic and phosphonic acids are known to form open frameworks (i.e. porous materials), particularly with first-row transition metal ions. Lanthanide diphosphonates with 3D pillared-layer structure are also known and several classes of ligands such as sim-... 

On the macroscopic scale, pillared layer structures are frequently found in ancient buildings, such as the Parthenon in Athens. Even on the microscopic scale, the pillared layer motif is very useful for the construction of various porous frameworks, because simple modification of a pillar module can be used to control porous structures and properties. The Cu11 coordination polymers, [Cu2(pzdc)2(L)] (L = pillar ligand), known as coordination pillared layers (CPLs), have pillared layer structures and are a suitable system for the design of porous functionalities.78 107 108 Two-dimensional... 

Two other major types of M41S materials are MCM-48 (with 3-D pores) and MCM-50 (with a pillared layer structure). 

Adsorption by Clays, Pillared Layer Structures and Zeolites... 

The metal phosphonate compounds usually adopt layered or pillared layered structures with the organic moieties filling in the inter-layer spaces [1-4]. The layered nature makes them interesting candidates to host intercalation reactions. Furthermore, the potential for the organic moieties to be modified by functional groups allows for the preparation of a number of new materials that have possible applications in areas such as catalysis, ion exchange, sensing and ion conduction [1,4-7]. 

Shiga, T., Okawa, H., Kitagawa, S., and Ohba, M. (2006) Stepwise synthesis and magnetic control of trimetal-lic magnets [Co2Ln(L)2(H20)4][Cr(CN)6] nH20 (Ln = La, Gd H2L = 2,6-di(acetoacetyl)pyridine) with 3-D pillared-layer structure. Journal of the American Chemical Society, 128, 16426-16427. 

Pillared Layered Structures (PLS) From Microporous to Nano-phase Materials... 

I. V. Mitchell (ed.). Pillared Layered Structures, Elsevier, New York, (1990)... 

Figure 11. Catalytic activity as a function of the nature of the pillaring element for some pillared montmorillonites in the acylation of mesitylene with acetyl chloride (reaction temperature = 473 K reaetion time = 15 min AZA and FAZA supported by Concerted European Action-Pillared Layered Structures (CEA-PLS) EXM-534 and EXM-551 provided by Slid Chemie) [62].

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