Rational Synthesis of Elusive Organic-Inorganic Hybrid Metal-oxo Clusters: Formation and Post-functionalization of Hexavanadates

Abstract

Paving the way towards new functional materials relies increasingly on the challenging task of forming organic-inorganic hybrid compounds. In that regard, discrete atomically-precise metal-oxo nanoclusters have received increasing attention due to the wide range of organic moieties that can be attached onto them through functionalization reactions. The Lindqvist hexavanadate family of clusters ([V6O13{(OCH2)3C-R}2]2-; V6-R) is particularly interesting due to its magnetic, redox, and catalytic properties. However, compared to other metal-oxo cluster types it has been less extensively explored, which is mainly due to poorly understood synthetic challenges and the limited number of viable post-functionalization strategies. In this work, we present an in-depth investigation of the factors that influence the formation of hybrid hexavanadates (V6-R HPOMs) and leverage this knowledge to develop [V6O13{(OCH2)3CNHCOCH2Cl}2]2- (V6-Cl) as a new and tunable platform for the facile formation of discrete hybrid structures based on metal-oxo clusters in high yields. Moreover, we showcase the versatility of the V6-Cl platform through its facile post-functionalization via nucleophilic substitution with various carboxylic acids of differing complexity and with functionalities that are relevant in multiple disciplines of chemistry, such as supramolecular chemistry and biochemistry. Hence, V6-Cl was shown to be a straightforward and versatile starting point for the formation of functional supramolecular structures or other hybrid materials, thereby enabling their exploration in various fields.