Solid state magic angle spinning nuclear magnetic resonance (NMR) and X-ray diffraction (XRD) were used to investigate the inverse behavior and vacancy disorder in alumina-rich spinel, MgAlO (0 ≤ x ≤ 0.86). Simulation and integration of NMR spectra have been developed for probing the population of Al located in different coordinated environments. Rietveld profile refinements were performed for powder XRD spectra by combining with NMR analysis. With changes in the composition, inversion disorder and cationic vacancies coexisting in tetrahedral and octahedral coordinations fluctuate in amount in the crystal lattice. The coordination polyhedra in the crystal structure can adjust the volume to variations of composition, anion parameter, and inverse parameter. This opens a window to the design and functionalization of spinel materials.
Five new uranyl coordination polymers were prepared by the hydrothermal method based on 5-nitroisophthalic acid (H 2 nip) as(5) [2,2′-bpy = 2,2′-bipyridine, 4,4′-bpy = 4,4′bipyridine, bpe = 4,4′-vinylenedipyridine, bpp = 4,4′ -trimethylenedipyridine, tmp = tetramethylpyrazine]. All of these synthesized complexes have been characterized by single crystal and powder X-ray diffraction, IR spectra, thermogravimetric analysis, elemental analysis, and luminescent properties. In particular, it is found that compounds 1 and 4 can be used as a luminescent sensor to efficiently detect arginine in aqueous solution by means of "turn-on"; the detection limits were 1.06 × 10 −6 and 6.42 × 10 −6 mol/L, respectively. Moreover, 4 can also be used as a bifunctional sensor for selective sensing of MnO 4 − anion by "turn-off". The detection limit of MnO 4 − in water was 1.79 × 10 −6 mol/L; the K sv was 1.88 × 10 4 . The sensing effect of arginine in simulated grape juice samples and MnO 4 − in simulated river water samples was also investigated by this sensing system with high recovery. In addition, the possible mechanism of sensing arginine and MnO 4 − in the aqueous solution was discussed.
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