Polyoxovanadate-Based Metal-Organic Octahedron Based on 1,4-Naphthalenedicarboxylic Acid

A new polyoxovanadate-based metal-organic octahedron (VMOP-26) was synthesized from vanadium acetylacetonate and 1,4-naphthalenedicarboxylic acid (1,4-H2NDC) under solvothermal condition and characterized by single crystal X-ray diffraction, powder X-ray diffraction, infrared spectroscopy and thermogravimetric analysis. The structure of VMOP-26 was composed of six {V5O9Cl} clusters and twelve 1,4-NDC ligands with regular octahedral geometry in which the polyoxovanadate clusters act as vertices and 1,4-NDC as edges. Each octahedron was surrounded by twelve adjacent octahedra with edge-to-edge connection modes. The absorption ability toward the dye molecules of VMOP-26 was investigated because VMOP-26 was an anionic cage. The results exhibit that only cationic dyes (Methylene blue (MB+), crystal violet (CV+), Rhodamine B (RhB+)) can be absorbed into the crystal lattice of VMOP-26, which indicates that the cationic dye absorption is an ion-exchange process. Besides, the fluorescent property of VMOP-26 was also investigated.