Coordination polymers porosity

Daiguebonne, C. Kerbellec, N. Bernot, K. Gerault, Y. Deluzet, A. Guillou, O. Synthesis, Crystal Structure, and Porosity Estimation of Hydrated Erbium Terephthalate Coordination Polymers. Inorg Chem. 2006, 45, 5399-5406. 

Transition metal complexes are interesting as bio-inorganic model systems [155-157] and also because of their material properties (conductivity, magnetism, porosity) and as potential hosts for a variety of guests [156-161]. Whereas salt-like 2D-Cun-coordination polymers are well documented [158-162], far less is known about their neutral counterparts. 

The first study of catalysis by a nanoporous coordination polymer used a simple lamellar coordination polymer of Cd and 4,4 -bipyridine in which several aldehydes were tested for cyanosilation with cyanotrimethylsilane.86 Good yields were found for smaller molecules, with progressively poorer yields for larger ones, while control experiments using Cd(N03)2 and 4,4 -bipyridine as catalysts resulted in no reaction, confirming the role of the coordination polymer s porosity in catalyzing the reaction. 

Several drawbacks limit the utility of the hybrid metal oxides prepared to date. Firstly, it has proven extremely difficult to create materials with porosity as high as is in coordination polymers. This is especially true in the case of materials with two- and three-dimensional M-O-M frameworks. Secondly, while some examples of these materials have relatively high magnetic ordering temperatures, there are still no examples that order at or above room temperature. However, there do not appear to be any fundamental reasons why these difficulties cannot be overcome. 

Keywords Carbon dioxide storage Coordination polymer Fuel gas storage Gas separations Hydrogen storage Metal-organic framework Methane storage Porosity... 

Tetra- and trinuclear SBUs have also been reported as constituents of porous and magnetic coordination polymers. Coordination polymers constructed around Co [144] and cubane-like Ln [145] assemblies have been reported, and these systems present contrasting porosity and robustness, but show only weak and predominant antiferromagnetic interactions at low temperature. Very recently, Yang and co-workers described a series of 3-D lanthanide-transition MOFs constructed around two distinct tetranuclear units of Ln cubanes and chair-like Cu clusters [146]. 

An important idea suggested by the chemistry of coordination polymers is higher-order assembly of squares and other structures into large void-volume, high-porosity... 

The observation that some of the new MOF compounds, such as MIL-53 (Chapter 7) and other coordination polymers,are highly flexible, and that for some adsorbates the porosity becomes accessible only at elevated adsorbate pressure (Figure 7.12), suggests that these materials could be used as sensors and actuators in response to increases in pressures. It may also be possible to use breathing solids in separations that are dominated by the effects of the fit of molecules within the flexible host. 

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