A Flexible Photoactive Titanium Metal-Organic Framework Based on a [TiIV3(μ3-O)(O)2(COO)6] Cluster

• Published in: Angewandte Chemie International Edition Vol. 54; no. 47; pp. 13912 - 13917
• Main Authors: Bueken, Bart, Vermoortele, Frederik, Vanpoucke, Danny E. P., Reinsch, Helge, Tsou, Chih-Chin, Valvekens, Pieterjan, De Baerdemaeker, Trees, Ameloot, Rob, Kirschhock, Christine E. A., Van Speybroeck, Veronique, Mayer, James M., De Vos, Dirk
• Format: Journal Article
• Language: English
• Published: Weinheim WILEY-VCH Verlag 16.11.2015; WILEY‐VCH Verlag; Wiley Subscription Services, Inc
• Edition: International ed. in English
• Subjects: metal-organic frameworks; metallocenes; molecular modeling; photochemistry; titanium; molecular modeling; photochemistry; titanium; metal-organic frameworks; metallocenes
• ISSN: 1433-7851; 1521-3773
• DOI: 10.1002/anie.201505512

The synthesis of titanium–carboxylate metal–organic frameworks (MOFs) is hampered by the high reactivity of the commonly employed alkoxide precursors. Herein, we present an innovative approach to titanium‐based MOFs by the use of titanocene dichloride to synthesize COK‐69, the first breathing Ti MOF, which is built up from trans‐1,4‐cyclohexanedicarboxylate linkers and an unprecedented [TiIV3(μ3‐O)(O)2(COO)6] cluster. The photoactive properties of COK‐69 were investigated in depth by proton‐coupled electron‐transfer experiments, which revealed that up to one TiIV center per cluster can be photoreduced to TiIII while preserving the structural integrity of the framework. The electronic structure of COK‐69 was determined by molecular modeling, and a band gap of 3.77 eV was found. A breath of fresh air: Titanocene dichloride was used as the metal source in an innovative synthetic approach to titanium‐based metal–organic frameworks (MOFs). In this way, a breathing Ti MOF (designated COK‐69) featuring a photoactive trinuclear cluster was built up from trans‐1,4‐cyclohexanedicarboxylate and an unprecedented, photoactive [TiIV3(μ3‐O)(COO)6] inorganic building unit (see picture).