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In this chapter, a brief introduction is given to some of the more common coordination complexes that make up connecting nodes in the increasingly ubiquitous field of metal organic frameworks (MOFs). A specific focus is directed on those motifs which allow for the generation of open metal sites within these microporous crystalline frameworks, specifically in the case of MOFs containing carboxylate-based organic linkers. Some of the proposed and upcoming applications of open metal sites in MOFs are discussed, along with select examples where the host–guest interaction of the framework with a substrate molecule is mediated by metal-bridging ligands such as hydroxide. Particular attention is given to introducing those studies which seek to investigate the variation in guest binding as a function of changing metal ions within the frameworks. Finally, several examples of catalysis in MOFs are presented, demonstrating the utility of open metal sites within such frameworks and highlighting the potential advantages of pore control over more traditional heterogeneous catalysts.

A series of new group 2 coordination polymers, MgL ={MgL(H 2 O)(DMF) 0.75 } ∞ , CaL = {CaL(DMF) 2 } ∞ , SrL = {SrL(H 2 O) 0.5 } ∞ and BaL = {BaL(H 2 O) 0.5 } ∞ , were synthesized using a flexible benzimidazolone diacetic acid linker ( H 2 L ) in which the two carboxylic acid binding sites are connected to a planar core via {–CH 2 –} spacers that can freely rotate in solution. In a ‘curiosity-led' diversion from group 2 metals, the first row transition metal salts Mn 2+ , Cu 2+ and Zn 2+ were also reacted with L to yield crystals of MnL = {MnL(DMF)(H 2 O) 3.33 } ∞ , Cu 3 L 2 = {Cu 3 L 2 (DMF) 2 (CHO 2 ) 2 } ∞ and ZnL = {ZnL(DMF)} ∞ . Crystal structures were obtained for all seven materials. All structures form as two-dimensional sheets and contain six-coordinate centres, with the exception of ZnL, which displays tetrahedrally coordinated metal centres, and Cu 3 L 2 , which contains square planar coordinated metal centres and Cu paddle-wheels. In each structure, the linker adopts one of two distinct conformations, with the carboxylate groups either cis or trans with respect to the planar core. All materials were also characterized by powder X-ray diffraction and thermogravimetric analysis.

A synthesis of the naturally occurring xanthone toxyloxanthone B is described, in which the key step is the regioselective addition of a methyl salicylate to a substituted benzyne followed by cyclization of the intermediate aryl anion to form the xanthone, the regiochemistry of the aryne addition being confirmed by X-ray crystallography. Subsequent introduction of the pyran ring by [3,3]-rearrangement and deprotection completed the synthesis

A synthesis of the naturally occurring xanthone toxyloxanthone B is described, in which the key step is the regioselective addition of a methyl salicylate to a substituted benzyne, followed by cyclization of the intermediate aryl anion to form the xanthone, the regiochemistry of the aryne addition being confirmed by X-ray crystallography. Subsequent introduction of the pyran ring by [3,3]-rearrangement and deprotection completed the synthesis.

Two different SURMOF films have been grown on a transparent conducting surface for spectro-electrochemical characterisation of radical species., The application of metal–organic framework (MOF) materials in electrochemical and electrochromic devices remains rare. One of the main reasons for this is the inability to readily access their detailed electrochemistry. The inherent insolubility of these materials does not allow interrogation by traditional solution-based electrochemical or spectroscopic methods. In this study, we report a straightforward alternative approach to the spectroelectrochemical study of MOFs. We have used two systems as exemplars in this study, MFM-186 and MFM-180. The method involves chemical modification of a working electrode to attach MOF materials without using corrosive reagents such as inorganic acids or bases which otherwise could limit their application in device development. MFM-186 demonstrates the formation of a stable radical species [MFM-186]˙+ on electrochemical oxidation, and this has been characterised by electrochemical, spectroelectrochemical and EPR spectroscopic techniques coupled to DFT analysis.