[Spectroscopy and thermostability of series rare-earth complexes with 3-nitrophthalic acid].

A series of rare-earth compound RE2L2 (HL)2 (H2O)6 x 2H2O (RE=La, Nd, Eu, Tb, Er, Y) containing 3-nitrophthalic acid (H2L) ligand were synthesized from ethanol-water solution, and characterized and investigated by the element analysis, infrared and ultraviolet absorption spectra and different thermal-thermogravimetric analysis. The results of the spectroscopic analysis were conformed to the crystal structures determined by X-ray diffraction, showing that the carboxylate (-COO-) and carboxyl (-COOH) groups of the ligand link to the rare-earth ions by bridging and terminal mode respectively. Two rare-earth ions were linked by two di-deprotonated ligand L(2-) in bridging-chelating mode to form a dinuclear structure, and coordinated by the other two mono-deprotonated ligands HL-in terminal chelating mode using their carboxylate (-COO-) and carboxyl (-COOH) group together, respectively. The IR spectra shows the existence of the carboxylate (-COO-) and carboxyl (-COOH) group and the hydrogen bond interactions between the carboxyl (-COOH) group and crystal water. The DTA-TGA data were consistent with the composition of compounds, exhibiting an endothermic peak of the loss of the crystal and coordinated waters at about 150 degrees C and two exothermic peaks of the oxidation and decomposition of ligands in the rang of about 340 to 460 degrees C.

[Synthesis and spectral characterization of rare-earth-ortho-amino phenylbenzoate-2,2'-bipyridine complexes].

The solid rare-earth complexes were synthesized using rare-earth ions (RE=Tb, Nd, Sm, La) reacting with ortho-amino phenylbenzoic acid (L) and 2,2'-bipyridine (bipy). Their compositions were confirmed and the spectral properties were characterized by element analysis, infrared and ultraviolet absorption spectra, and DTA-TGA. The fluorescent properties of complexes TbL3 and TbL3 x bipy x 3H2O were also measured and discussed. The result shows that the fluorescence intensity of TbL3 x bipy 3H2O is stronger than that of TbL3.

[Identification of official rhubarb samples based on IR spectra and neural networks].

The Fourier transform infrared (IR) spectrometry and neural networks have been used to identification of official and un-official rhubarb samples in the present work. The IR spectra were compressed by using wavelet transform and then were normalized prior to network training. Spectra with 700 data points were compressed to 44 variables, therefore, the training process of neural networks were speed up. 52 rhubarb samples in which 25 official and 27 unofficial rhubarb samples are included have been used to network modeling. The effects of neuron number in hidden layer and momentum parameter on classification have been investigated. Results showed that about 98% rhubarb samples could be identified correctly when optimized parameters were used. This method can be useful for quality control in rhubarb-contained Chinese medicine production.

[The synthesis, 1H NMR and IR study of [(n-Bu)4N]2[Mo2O5(OC10H6O)2] and [(n-Bu)4N]2[Mo4O10 (OC10H6O)2(OCH3)2]].

The title organo-molybdate derivatives are synthesized and their IR, 1H NMR spectra have been determined and the relations between the structures and the 1H NMR and IR parameters have been studied. The results indicate that the red shift of the IR frequency of Mo-O-Mo in [(n-Bu)4N]2[Mo2O5(OC10H6O)2] (complex I) takes place to compare with that in [(n-Bu)4N]2[Mo4O10 (OC10H6O)2(OCH3)2] (complex II) and lower filed shift of 1H NMR of the aromatic H atoms in complex II occurs as contrasted to that in the complex I. It is found also the organo-molybdate derivatives are very sensitive to the acidity of the chemical system.