In the last decades, poly(methyl methacrylate) (PMMA) has been widely studied due to its outstanding mechanical, chemical, and physical properties. In this article, the PMMA composites doped with an excited state intramolecular proton transfer (ESIPT) compound 3-hydroxy-2-naphthoic acid (3HNA) are reported. The 3HNA-doped PMMA composites were synthesized by in situ polymerization and characterized by Fourier transform infrared spectra, ultraviolet absorption spectra, fluorescence spectra, and thermogravimetric analysis. The effect of 3HNA and various solvents on the fluorescent properties of the PMMA composites was systematically investigated. The results indicated that the emission spectra of the 3HNA-doped PMMA composites exhibited 3HNA dual emission. A violet emission was observed in 3HNA-doped PMMA composites containing nonpolar solvents or weak polar solvents, whereas the composites containing strong polar solvents exhibited a large Stokes-shifted green fluorescence, which was attributed to the ESIPT of 3HNA.
Three novel binary Tb(III) complexes (TbL2, TbL, and Tb2L; L=3,3',4,4'-biphenyl tetracarboxylic ligand) were synthesized by changing the molar ratio of Tb(III) to 3,3',4,4'-biphthalic anhydride (BPDA) (1∶2, 1∶1, and 2∶1, respectively). IR spectra indicate that there are two coordination modes of the carboxylate ligands with Tb3+ ions in the complexes. Most of them are in bridging mode; the others are in chelating mode. These complexes all have good thermal stability. The photophysical properties of these complexes are studied in detail using UV absorption spectra, fluorescence spectra, and transient fluorescence spectra. The results indicate that the photoluminescence properties of the complexes depend strongly on the molar ratio of Tb(III) to BPDA. When the molar ratio of Tb(III) to BPDA is 1∶1, complex TbL exhibits the strongest yellow light emission among the three Tb(III) complexes. However, complex Tb2L exhibits a weaker yellowish-green light emission when the molar ratio of Tb(III) to BPDA is 2∶1. The phenomenon of the yellow emission from terbium complexes is rarely reported.
Spectrum technology in coal quality detection has become a research hotspot with the maturing of spectral technology and the continuous development of spectral imager. This article mainly analyzed and summarized the progress and research status of scholars at home and abroad based on the coal quality index (moisture, ash content, volatile matter, fixed carbon and sulfur content).According to the coal quality index, we demonstrated spectrum technology has considerable prospects in coal quality testing by analysis the application of spectrum technology in detection of other material's corresponding index.
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