A one-dimensional supramolecular chain based on [H2V10O28]4− units decorated with 4-dimethylaminopyridinium ions: an experimental and theoretical characterization

The compound [DMAPH](4)[H2V10O28]center dot 5H(2)O (1), where DMAPH is a 4-dimethylaminopyridinium ion [C7H11N2](+), crystallized in a monoclinic cell (space group P21/n). The X-ray analysis revealed that the protic units [H2V10O28](4-) are linked via cyclic double hydrogen bonds forming a 1D supramolecular structure along the [010] direction, which is decorated by DMAPH cations via close N-H center dot center dot center dot O contacts (d(H center dot center dot center dot O) = 1.88 angstrom). The experimental IR and Raman spectra of this compound are characterized by strong and medium bands in the 1000-400 cm(-1) region, attributed to stretching and bending modes of the V-O bonds. DFT-D3/CPCM methods were used to further study the vibrational modes of both [V10O28](6-) and [H2V10O28](4-) anions and also of compound 1. For all compounds, the region of 990-860 cm(-1) showed the modes corresponding to the symmetric V-O-H bending coupled with the VQO stretching of the decavanadate moiety. Aqueous V-51 NMR spectroscopy showed the classical resonances for the V5+ octahedral centers found in the decavanadate ion. Non-covalent interactions in the supramolecular structure were studied by analysis of topological parameters by QTAIM. The nature of the [H2V10O28](4-) unit as a donor/acceptor group was explored using 2D-fingerprint plots obtained from the molecular Hirshfeld surface. Given the structural characteristics of [DMAPH](4)[H2V10O28]center dot 5H(2)O, it could be suggested that this compound could act as a slow releasing prodrug of the decavanadate ion, species that have been useful as an antidiabetic agent in type 1 and type 2 rat models of diabetes mellitus.