Ti8O8(OOCR)16, a New Family of Titanium-Oxo Clusters: Potential NBUs for Reticular Chemistry

• Published in: European Journal of Inorganic Chemistry Vol. 2010; no. 36; pp. 5650 - 5659
• Main Authors: Frot, Théo, Cochet, Sébastien, Laurent, Guillaume, Sassoye, Capucine, Popall, Michael, Sanchez, Clément, Rozes, Laurence
• Format: Book Review Journal Article
• Language: English
• Published: Weinheim WILEY-VCH Verlag 01.12.2010; WILEY‐VCH Verlag; Wiley-VCH Verlag
• Subjects: Chemical Sciences; Cluster compounds; Material chemistry; Metal-organic frameworks; Nanostructures; Titanates; Titanates; Nanostructures; Metal–organic frameworks; Cluster compounds
• ISSN: 1434-1948; 1099-0682
• DOI: 10.1002/ejic.201000807

The reactions of titanium alkoxides with a large excess of different carboxylic acids under nonhydrolytic conditions leads to the reproducible formation of well‐defined nano‐building units (NBUs) with the formula [Ti8O8(OOCR)16] [R = C6H5, C(CH3)3, CH3]. The structures of these titanium–oxo–carboxylate clusters have been determined by crossingdifferent characterization techniques and methodologies (single‐crystal X‐ray diffraction, 13C and 1H NMR spectroscopy, and FTIR spectroscopy). These NBUs are obtained in high yields and, since all the alkoxo ligands have been removed by using solvothermal‐synthesis conditions, they present better stability upon hydrolysis than the often reported alkoxo–carboxylate–titanium–oxo clusters [TinO2n–x/2–y/2(OR′)x(OOCR)y] (n ≥ 2; x ≥ 1; y ≥ 1). In addition, the solubility and transferability of these clusters in common solvents can be tuned by selecting the nature of the organic ligand. Moreover, we also report for the first time, a robust post‐modification of the carboxylate ligands by transesterification reactions on the titanium–oxo clusters. These reactions keep the integrity of the octameric titanium–oxo core intact, while completely exchanging the organic shell of the cluster. This family of [Ti8O8(OOCR)16] clusters, which present 16 points of extension, a symmetric shape, and the ability to be post‐modified with conservation of the core structure, can therefore be considered as interesting NBUs to form new metal–organic frameworks. New titanium–oxo clusters have been synthesized. The clusters [Ti8O8(OOCR)16], consisting of an octameric oxo core surrounded by 16 carboxylate ligands, are obtained under solvothermal conditions inhigh yields. For the first time, the ability of these nanoobjects to be post‐modified by other organic acids with the preservation of the octameric oxo core is demonstrated.