A phase transformable ultrastable titanium-carboxylate framework for photoconduction

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A phase transformable ultrastable titanium-carboxylate framework for photoconduction, Nature Communications9, 1660 (2018)

 

We report herein a porous 3D mdip-based Ti-MOF, namely MIL-177-LT (MIL stands for Materials from Institut Lavoisier, LT for low temperature form and mdip for 3,3′,5,5′-tetracarboxydiphenylmethane), also denoted MIP-177-LT (MIP stands for Materials from Institute of Porous Materials of Paris). MIL-177-LT, with the formula Ti12O15(mdip)3(formate)6, was prepared under mild, scalable reaction conditions by simply refluxing a mixture of Ti(iPrO)4, H4mdip and formic acid. Its honeycomb crystal structure, which features nano-sized pores, is composed of a Ti12O15 cluster secondary building unit (SBU) with a high condensation degree of 1.25, surpassing that of all previously reported Ti-MOFs. Furthermore, MIL-177-LT can survive under extremely acidic conditions, including aqua regia and concentrated H3PO4. One can also introduce, through a direct synthesis, significant amounts of iron(III) into this structure with adjustable ratios and homogeneous distributions, in order to tune the electrical conductive behavior of the solid. It is worth noting that a thermally induced phase transformation of MIL-177-LT to its high-temperature (HT) form, MIL-177-HT, leads to the formation of a one-dimensional (1D) infinite Ti–O subunit (Ti6O9)n with an even higher condensation degree of 1.5, while maintaining its highly crystalline porous architecture. This high-temperature form displays a strongly enhanced photoresponsive ability, as compared to MIL-177-LT, and far exceeds the performance of other discrete SBU-based Ti-MOFs, such as MIL-12516. In addition, the introduction of conductive polythiophene into its pores gives rise to an enhanced charge separation lifetime upon irradiation. To the best of our knowledge, this serves as the first example in porous materials, MOFs or otherwise, that demonstrates the alteration of the dimensionality of the inorganic buildin.

 

 

Pour plus d'informations, consultez le commniqué de presse associé à cet article : À la recherche d’un oxyde de titane poreux !

 

Nature Communications9, 1660 (2018)

 

Porous titanium oxide materials are attractive for energy-related applications. However, many suffer from poor stability and crystallinity. Here we present a robust nanoporous metal–organic framework (MOF), comprising a Ti12O15 oxocluster and a tetracarboxylate ligand, achieved through a scalable synthesis. This material undergoes an unusual irreversible thermally induced phase transformation that generates a highly crystalline porous product with an infinite inorganic moiety of a very high condensation degree. Preliminary photophysical experiments indicate that the product after phase transformation exhibits photoconductive behavior, highlighting the impact of inorganic unit dimensionality on the alteration of physical properties. Introduction of a conductive polymer into its pores leads to a significant increase of the charge separation lifetime under irradiation. Additionally, the inorganic unit of this Ti-MOF can be easily modified via doping with other metal elements. The combined advantages of this compound make it a promising functional scaffold for practical applications.

 

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A phase transformable ultrastable titanium-carboxylate framework for photoconduction

 

Sujing Wang, Takashi Kitao, Nathalie Guillou, Mohammad Wahiduzzaman, Charlotte Martineau-Corcos, Farid Nouar, Antoine Tissot, Laurent Binet, Naseem Ramsahye, Sabine Devautour-Vinot, Susumu Kitagawa, Shu Seki, Yusuke Tsutsui, Valérie Briois, Nathalie Steunou, Guillaume Maurin, Takashi Uemura and Christian Serre

 

Nature Communications9, 1660 (2018)

 

DOI: 10.1038/s41467-018-04034-w