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.
Dan-Hardi
Meenakshi
M
Institut Lavoisier, UMR CNRS 8180, Université de Versailles St-Quentin-en-Yvelines, 45 Avenue des Etats-Unis, 78035 Versailles Cedex, France.
Serre
Christian
C
Frot
Théo
T
Rozes
Laurence
L
Maurin
Guillaume
G
Sanchez
Clément
C
Férey
Gérard
G
D000327:Adsorption; D000438:Alcohols; D003460:Crystallization; D003998:Dicarboxylic Acids / Q000737:chemistry*; D004583:Electrons; D009584:Nitrogen; D055668:Photochemical Processes; D016062:Porosity; D014025:Titanium / Q000737:chemistry*
D000438:Alcohols; D003998:Dicarboxylic Acids; D014025:Titanium; D009584:Nitrogen