Rational design and synthesis of organic-inorganic hexavanadate hybrids with p-halogenated benzoyl ligands

Three original hexavanadate-based materials (DIEA)(2)[V6O13{(OCH2)(3)CNHCOC6H4X-p)}(2)] (X = Cl, Br, I) have been synthesized via the amidation of H-2[V6O13{(OCH2)(3)CNH2}(2)] and p-halogenated benzoic acid. The components and structures of the products were determined by FT-IR, H-1 NMR, ESI-MS, XPS and single-crystal X-ray diffraction. The molecular structures of three compounds are similar: a Lindqvist-type cluster {V6O19} covalently links to two halogenated benzoyl trialkoxyl ligands. However, they exhibit diverse packing manners because of their difference in hydrogen-bonding interactions. The anions [V6O13{(OCH2)(3)CNHCOC6H4Cl-p)}(2)](2-) are arranged in a 1D chain structure by intermolecular hydrogen-bonding interactions, while the other two compounds show a 2D "sandwich biscuit" layered packing structure without hydrogen bonds between the anions. Moreover, when choosing a condensing agent to increase the yield, PyBOP has an overwhelming advantage over common EDCI/HOBt. This article also discusses the reaction mechanism in detail, and provides experimental guidance for the rational design of POM-based organic-inorganic hybrids. (C) 2021 Elsevier B.V. All rights reserved.