Crystal and Functional Engineering for Unique Microporous Materials

Department of Synthetic Chemistry and Biological Chemistry, Kyoto University
○Susumu Kitagawa

The recent advent of porous coordination polymers (PCPs) or metal-organic frameworks (MOFs), as new functional microporous adsorbents, has attracted the attention of chemists due to scientific interest in the creation of unprecedented regular nano-sized spaces and in the finding of novel phenomena, as well as commercial interest in their application for storage, for separation and in heterogeneous catalysis.1-4 One of the advantages of PCPs, as compared with other microporous materials such as activated carbons, is designability, which provides a variety of surface properties based on organic ligands with functional groups, affording the potential to make the pore surfaces hydrophobic, hydrophilic, chiral and so on. This prominent feature leads us to expect that PCPs will show a high adsorption capability for specific molecules. However, few useful concepts and strategies for specific adsorption of smaller molecules have been established to date. Here, we have found superb sorption of C2H2 molecules on the functionalized surface of an PCP and show an enhanced “confinement effect”, which can be achieved by precisely and regularly arranged functionalities in the nano-sized pore wall, applicable to a highly stable, selective adsorption system.5 We have succeeded in obtaining interesting array structures of benzene6 and O2 7 molecules and observed their unusual properties in the nanochannel. Recently, we have utilized the regular and tunable nanochannels of PCPs for fields of polymerization, which allows controlled living radical polymerization aswell as stereoregulated polymerization of substituted acetylenes,8 opening up a new dimensions in the field of porous materials

Reviews 1) S. Kitagawa et.al., Bull. Chem. Soc. Jpn, (Accounts), 1998, 71, 1739. 2) S. Kitagawa, et.al., Angew. Chem. Int. Ed,, 2004, 43, 2334. 3) S. Kitagawa et.al., Chem. Soc. Rev. 2005, 34, 109. 4) S. Kitagawa et.al., Chem. Commun. Feature Article,2006,701.
Original Papers 5) R. Matsuda, et.al., Nature, 2005, 436, 238. 6) R. Matsuda, et.al., J. Am. Chem. Soc. 2004, 43, 14063. 7) R. Kitaura, et.al., Science, 2002, 298, 2358. 8)) T. Uemura, et.al., Chem. Commun. 2005, 5968.