A Titanium-Organic Framework as an Exemplar of Combining the Chemistry of Metal- and Covalent-Organic Frameworks.

A crystalline material with a two-dimensional structure, termed metal-organic framework-901 (MOF-901), was prepared using a strategy that combines the chemistry of MOFs and covalent-organic frameworks (COFs). This strategy involves in situ generation of an amine-functionalized titanium oxo cluster, Ti6O6(OCH3)6(AB)6 (AB = 4-aminobenzoate), which was linked with benzene-1,4-dialdehyde using imine condensation reactions, typical of COFs. The crystal structure of MOF-901 is composed of hexagonal porous layers that are likely stacked in staggered conformation (hxl topology). This MOF represents the first example of combining metal cluster chemistry with dynamic organic covalent bond formation to give a new crystalline, extended framework of titanium metal, which is rarely used in MOFs. The incorporation of Ti(IV) units made MOF-901 useful in the photocatalyzed polymerization of methyl methacrylate (MMA). The resulting polyMMA product was obtained with a high-number-average molar mass (26 850 g mol(-1)) and low polydispersity index (1.6), which in many respects are better than those achieved by the commercially available photocatalyst (P-25 TiO2). Additionally, the catalyst can be isolated, reused, and recycled with no loss in performance.

[1]  Qiang Zhang,et al.  A single crystalline porphyrinic titanium metal–organic framework† †Electronic supplementary information (ESI) available. CCDC [1036868]. For ESI and crystallographic data in CIF or other electronic format. See DOI: 10.1039/c5sc00916b Click here for additional data file. Click here for additional da , 2015, Chemical science.

[2]  Amy J. Cairns,et al.  Quest for highly connected metal-organic framework platforms: rare-earth polynuclear clusters versatility meets net topology needs. , 2015, Journal of the American Chemical Society.

[3]  C. Su,et al.  Highly porous aerogels based on imine chemistry: syntheses and sorption properties , 2015 .

[4]  Michael O'Keeffe,et al.  Reticular synthesis and the design of new materials , 2003, Nature.

[5]  Krista S. Walton,et al.  Strategies for Characterization of Large-Pore Metal-Organic Frameworks by Combined Experimental and Computational Methods , 2009 .

[6]  C. Hawker,et al.  Control of a living radical polymerization of methacrylates by light. , 2012, Angewandte Chemie.

[7]  M. Dincǎ,et al.  Synthesis and Electrical Properties of Covalent Organic Frameworks with Heavy Chalcogens , 2015 .

[8]  M. Fujita,et al.  Shedding light on hidden reaction pathways in radical polymerization by a porous coordination network. , 2011, Chemical communications.

[9]  Aron Walsh,et al.  Engineering the optical response of the titanium-MIL-125 metal-organic framework through ligand functionalization. , 2013, Journal of the American Chemical Society.

[10]  Yinghua Jin,et al.  Desymmetrized Vertex Design for the Synthesis of Covalent Organic Frameworks with Periodically Heterogeneous Pore Structures. , 2015, Journal of the American Chemical Society.

[11]  R. Krishna,et al.  Tailor-Made Pore Surface Engineering in Covalent Organic Frameworks: Systematic Functionalization for Performance Screening. , 2015, Journal of the American Chemical Society.

[12]  S. Xu,et al.  One-step construction of two different kinds of pores in a 2D covalent organic framework. , 2014, Journal of the American Chemical Society.

[13]  H. Chun,et al.  Robust molecular crystals of titanium(IV)-oxo-carboxylate clusters showing water stability and CO2 sorption capability. , 2014, Inorganic chemistry.

[14]  L. Hubert-Pfalzgraf,et al.  Synthesis and characterization of new titanium hexanuclear oxo carboxylato alkoxides. Molecular structure of [Ti6(µ3-O)6(µ-O2CC6H4OPh)6(OEt)6] , 1998 .

[15]  Mohamed Eddaoudi,et al.  Assembly of metal-organic frameworks (MOFs) based on indium-trimer building blocks: a porous MOF with soc topology and high hydrogen storage. , 2007, Angewandte Chemie.

[16]  Amy J. Cairns,et al.  Versatile rare earth hexanuclear clusters for the design and synthesis of highly-connected ftw-MOFs , 2015, Chemical science.

[17]  M. O'keeffe,et al.  The Reticular Chemistry Structure Resource (RCSR) database of, and symbols for, crystal nets. , 2008, Accounts of chemical research.

[18]  Laurence Rozes,et al.  Titanium oxo-clusters: precursors for a Lego-like construction of nanostructured hybrid materials. , 2011, Chemical Society reviews.

[19]  T. Uemura,et al.  Radical Copolymerization Mediated by Unsaturated Metal Sites in Coordination Nanochannels. , 2015, ACS macro letters.

[20]  Omar M Yaghi,et al.  Design, synthesis, structure, and gas (N2, Ar, CO2, CH4, and H2) sorption properties of porous metal-organic tetrahedral and heterocuboidal polyhedra. , 2005, Journal of the American Chemical Society.

[21]  Yushan Yan,et al.  3D microporous base-functionalized covalent organic frameworks for size-selective catalysis. , 2014, Angewandte Chemie.

[22]  Michael O’Keeffe,et al.  The Chemistry and Applications of Metal-Organic Frameworks , 2013, Science.

[23]  Michael O’Keeffe,et al.  A crystalline imine-linked 3-D porous covalent organic framework. , 2009, Journal of the American Chemical Society.

[24]  T. Devic,et al.  Lanthanide Metal‐Organic Frameworks as Ziegler–Natta Catalysts for the Selective Polymerization of Isoprene , 2009 .

[25]  Rob Ameloot,et al.  A Flexible Photoactive Titanium Metal-Organic Framework Based on a [Ti(IV)3(μ3-O)(O)2(COO)6] Cluster. , 2015, Angewandte Chemie.

[26]  K. E. Cordova,et al.  Tailoring the Optical Absorption of Water-Stable Zr(IV)- and Hf(IV)-Based Metal-Organic Framework Photocatalysts. , 2015, Chemistry, an Asian journal.

[27]  T. Uemura,et al.  Radical Polymerization of Vinyl Monomers in Porous Coordination Polymers: Nanochannel Size Effects on Reactivity, Molecular Weight, and Stereostructure , 2008 .

[28]  Gérard Férey,et al.  A zirconium methacrylate oxocluster as precursor for the low-temperature synthesis of porous zirconium(IV) dicarboxylates. , 2010, Chemical communications.

[29]  T. Uemura,et al.  Radical polymerisation of styrene in porous coordination polymers. , 2005, Chemical communications.

[30]  Cory M. Simon,et al.  Kinetically tuned dimensional augmentation as a versatile synthetic route towards robust metal–organic frameworks , 2014, Nature Communications.

[31]  Jie Su,et al.  A series of highly stable mesoporous metalloporphyrin Fe-MOFs. , 2014, Journal of the American Chemical Society.

[32]  H. García,et al.  Evidence of photoinduced charge separation in the metal-organic framework MIL-125(Ti)-NH2. , 2012, Chemphyschem : a European journal of chemical physics and physical chemistry.

[33]  M. Antonietti,et al.  Mesoporous Graphitic Carbon Nitride as a Heterogeneous Visible Light Photoinitiator for Radical Polymerization. , 2012, ACS macro letters.

[34]  K. Landfester,et al.  Hierarchically porous pi-conjugated polyHIPE as a heterogeneous photoinitiator for free radical polymerization under visible light , 2014 .

[35]  Yangen Zhou,et al.  Amine-functionalized zirconium metal-organic framework as efficient visible-light photocatalyst for aerobic organic transformations. , 2012, Chemical communications.

[36]  Freek Kapteijn,et al.  Enhancing optical absorption of metal-organic frameworks for improved visible light photocatalysis. , 2013, Chemical communications.

[37]  H. Chun,et al.  Nonporous titanium-oxo molecular clusters that reversibly and selectively adsorb carbon dioxide. , 2013, Inorganic chemistry.