A new photoactive crystalline highly porous titanium(IV) dicarboxylate.

Titanium is a very attractive candidate for MOFs due to its low toxicity, redox activity, and photocatalytic properties. We present here MIL-125, the first example of a highly porous and crystalline titanium(IV) dicarboxylate (MIL stands for Materials of Institut Lavoisier) with a high thermal stability and photochemical properties. Its structure is built up from a pseudo cubic arrangement of octameric wheels, built up from edge- or corner-sharing titanium octahedra, and terephthalate dianions leading to a three-dimensional periodic array of two types of hybrid cages with accessible pore diameters of 6.13 and 12.55 A. X-ray thermodiffractometry and thermal analysis show that MIL-125 is stable up to 360 degrees C under air atmosphere while nitrogen sorption analysis indicates a surface area (BET) of 1550 m(2) x g(-1). Moreover, under nitrogen and alcohol adsorption, MIL-125 exhibits a photochromic behavior associated with the formation of stable mixed valence titanium-oxo compounds. The titanium oxo cluster are back oxidized in the presence of oxygen. This photochemical phenomenon is analyzed through the combined use of Electron Spin Resonance (ESR) and UV-visible absorption spectroscopies. The photogenerated electrons are trapped as Ti(III) centers, while a concomitant oxidation of the adsorbed alcohol molecules occurs. This new microporous hybrid is a very promising candidate for applications in smart photonic devices, sensors, and catalysis.

[1]  C. Serre,et al.  Large breathing effects in three-dimensional porous hybrid matter: facts, analyses, rules and consequences. , 2009, Chemical Society reviews.

[2]  U. Mueller,et al.  Metal–organic frameworks—prospective industrial applications , 2006 .

[3]  M. Che,et al.  Identification of oxygen species adsorbed on reduced titanium dioxide , 1971 .

[4]  U. Schubert Polymers Reinforced by Covalently Bonded Inorganic Clusters , 2001 .

[5]  Gérard Férey,et al.  Flexible porous metal-organic frameworks for a controlled drug delivery. , 2008, Journal of the American Chemical Society.

[6]  M. Burghammer,et al.  A microdiffraction set-up for nanoporous metal-organic-framework-type solids. , 2007, Nature Materials.

[7]  Young Kwan Park,et al.  Crystal structure and guest uptake of a mesoporous metal-organic framework containing cages of 3.9 and 4.7 nm in diameter. , 2007, Angewandte Chemie.

[8]  A. Kanaev,et al.  Laser-induced photopatterning of organic-inorganic TiO2-based hybrid materials with tunable interfacial electron transfer. , 2009, Physical chemistry chemical physics : PCCP.

[9]  P. Lightfoot,et al.  Synthesis, Structure and Properties of Related Microporous N,N‘-Piperazinebismethylenephosphonates of Aluminum and Titanium , 2006 .

[10]  D. Johnston,et al.  Polynuclear chromium(III) carboxylates. 1. Synthesis, structure, and magnetic properties of an octanuclear complex with a ring structure. , 2000, Inorganic chemistry.

[11]  José A.C. Silva,et al.  A Microporous Metal−Organic Framework for Separation of CO2/N2 and CO2/CH4 by Fixed-Bed Adsorption , 2008 .

[12]  Gérard Ferey,et al.  Rational design of porous titanophosphates. , 2003, Chemical communications.

[13]  Gérard Férey,et al.  Calculating Geometric Surface Areas as a Characterization Tool for Metal−Organic Frameworks , 2007 .

[14]  Gérard Férey,et al.  Hybrid porous solids: past, present, future. , 2008, Chemical Society reviews.

[15]  Peter Day,et al.  Mixed Valence Chemistry-A Survey and Classification , 1968 .

[16]  C. Sanchez,et al.  Titanium-Oxo Clusters, Versatile Nanobuilding Blocks for the Design of Advanced Hybrid Materials , 2006 .

[17]  M. O'Keeffe,et al.  Dense and rare four-connected nets , 1991 .

[18]  Omar M Yaghi,et al.  Exceptional H2 saturation uptake in microporous metal-organic frameworks. , 2006, Journal of the American Chemical Society.

[19]  Carlo Lamberti,et al.  A new zirconium inorganic building brick forming metal organic frameworks with exceptional stability. , 2008, Journal of the American Chemical Society.

[20]  U. Schubert Chemical modification of titanium alkoxides for sol–gel processing , 2005 .

[21]  S. Kaskel,et al.  Titanium terephthalate (TT-1) hybrid materials with high specific surface area , 2006 .

[22]  Gérard Férey,et al.  Metal-organic frameworks as efficient materials for drug delivery. , 2006, Angewandte Chemie.

[23]  C. Serre,et al.  An Explanation for the Very Large Breathing Effect of a Metal–Organic Framework during CO2 Adsorption , 2007 .

[24]  Y. Kawazoe,et al.  Highly controlled acetylene accommodation in a metal–organic microporous material , 2005, Nature.

[25]  J. Hupp,et al.  Alkali metal cation effects on hydrogen uptake and binding in metal-organic frameworks. , 2008, Inorganic chemistry.

[26]  Xian‐Ming Zhang,et al.  A twelve-connected Cu6S4 cluster-based coordination polymer. , 2005, Journal of the American Chemical Society.

[27]  B. Viana,et al.  Blue emitting hybrid organic–inorganic materials , 2001 .

[28]  T. Reineke,et al.  Assembly of metal-organic frameworks from large organic and inorganic secondary building units: new examples and simplifying principles for complex structures. , 2001, Journal of the American Chemical Society.

[29]  C. Hill,et al.  Catalytic photochemical dehydrogenation of organic substrates by polyoxometalates , 1985 .

[30]  J. Long,et al.  Hydrogen storage in the dehydrated prussian blue analogues M3[Co(CN)6]2 (M = Mn, Fe, Co, Ni, Cu, Zn). , 2005, Journal of the American Chemical Society.

[31]  T. Bein,et al.  Directing the structure of metal-organic frameworks by oriented surface growth on an organic monolayer. , 2008, Angewandte Chemie.

[32]  C. Sanchez,et al.  New photoactive hybrid organic–inorganic materials based on titanium-oxo-PHEMA nanocomposites exhibiting mixed valence properties , 2005 .

[33]  Rui Zhou,et al.  Twelve-connected net with face-centered cubic topology: a coordination polymer based on [Cu12(mu4-SCH3)6]6+ clusters and CN- linkers. , 2005, Angewandte Chemie.

[34]  Maria Cristina Burla,et al.  EXPO: a program for full powder pattern decomposition and crystal structure solution , 1999 .

[35]  Jinho Oh,et al.  A homochiral metal–organic porous material for enantioselective separation and catalysis , 2000, Nature.

[36]  C. Chuck,et al.  Air-stable titanium alkoxide based metal-organic framework as an initiator for ring-opening polymerization of cyclic esters. , 2006, Inorganic chemistry.

[37]  Susumu Kitagawa,et al.  Functional porous coordination polymers. , 2004, Angewandte Chemie.