Architectural control of urea in supramolecular 1D strontium vanadium oxide chains

Abstract

A facile bottom-up approach for the controlled self-assembly of infinite strontium vanadium oxide chains is presented. Two novel one-dimensional strontium-linked polyoxovanadate chains have been isolated by linkage of decavanadate clusters with strontium(II) ions. To control the architecture dimensions, urea was used as a critical control parameter which allowed tuning of the intra- and intermolecular spacings within the crystal lattice. Using N,N-dimethyl formamide (DMF) and urea as stabilizing ligands, a supramolecular structure, {[Sr(dmf)₃(CON₂H₄)₂][Sr(dmf)₂(CON₂H₄)₂][H₂V₁₀O₂₈]} (1) was obtained where cluster linkage is achieved through urea-bridged strontium dimers. In the absence of urea, a purely strontium-linked supramolecular architecture, {[Sr(dmf)₄]₂[H₂V₁₀O₂₈]} (2), is formed. The chain architectures were characterized by single crystal X-ray diffraction, elemental analysis, UV-Vis and FT-IR spectroscopy. In order to learn about the assembly and dis-assembly of 1D architectures ESI-mass-spectrometry was performed. The results show how simple organic ligands may be used to engineer the crystal lattice and illustrate that further work is needed to understand the exact mode of action of the urea ligands.