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Novel compounds of heavy rare earths (III) picolinates. A pyrolytic study using: TG-DSC-FTIR, HSM-MS and GC-MS
Journal of Analytical and Applied Pyrolysis ( IF 5.8 ) Pub Date : 2019-11-01 , DOI: 10.1016/j.jaap.2019.104709
A.L.C.S. Nascimento , G.P. Ashton , G.M.B. Parkes , B. Ekawa , R. P Fernandes , A.C.S. Carvalho , M. Ionashiro , F.J. Caires

Abstract Heavy trivalent lanthanides and yttrium picolinates were synthesized by complexation of basic rare-earth metal carbonates with an aqueous solution of picolinic acid. The novel compounds were obtained with the general formula Ln(L)3∙nH2O, where L is picolinate and n = 1.5 H2O (Dy, Ho, Yb, Lu and Y), 2 H2O (Tb and Tm) and 2.5 H2O (Er). The stoichiometry of the complexes was calculated through mass losses found using thermogravimetry (TG), complexometry and elemental analysis (EA). The thermal behavior in oxidative and pyrolytic atmospheres of the compounds was analyzed by simultaneous thermogravimetry - differential scanning calorimetry (TG-DSC). The gaseous products of the pyrolysis were determined throughout by monitoring the evolved species using TG-DSC couple to Fourier transform infrared spectroscopy (TG-DSC-IR), hot-stage microscopy mass spectrometry (HSM-MS), and gas chromatography-mass spectrometry (GC-MS). The obtained results validated mass loss assignments made using the TG curves. However, gaseous product analysis indicates the degradation processes are more complex than the thermoanalytical techniques suggest alone. This study used a GC-MS technique to identify the condensed gaseous products obtained during the second step of thermal degradation of the picolinate complexes. The analysis of the symmetric and asymmetric stretching frequencies of the carboxylate group in the IR spectra showed a monodentate bonding mode. The compounds were obtained in the amorphous state, as indicated by the powder x-ray diffractometry (PXRD) data.

中文翻译:

重稀土 (III) 吡啶甲酸酯的新型化合物。热解研究使用:TG-DSC-FTIR、HSM-MS 和 GC-MS

摘要 通过碱性稀土金属碳酸盐与吡啶甲酸水溶液络合,合成了重三价镧系元素和吡啶甲酸钇。新化合物的通式为 Ln(L)3∙nH2O,其中 L 是吡啶甲酸酯,n = 1.5 H2O(Dy、Ho、Yb、Lu 和 Y)、2 H2O(Tb 和 Tm)和 2.5 H2O(Er )。复合物的化学计量是通过使用热重法 (TG)、络合法和元素分析 (EA) 发现的质量损失来计算的。通过同时热重-差示扫描量热法(TG-DSC)分析化合物在氧化和热解气氛中的热行为。通过使用 TG-DSC 对傅里叶变换红外光谱 (TG-DSC-IR) 监测释放的物种,全程测定热解的气态产物,热台显微镜质谱 (HSM-MS) 和气相色谱-质谱 (GC-MS)。获得的结果验证了使用 TG 曲线进行的质量损失分配。然而,气体产物分析表明降解过程比单独的热分析技术更复杂。本研究使用 GC-MS 技术来鉴定在吡啶甲酸酯复合物热降解的第二步中获得的冷凝气态产物。红外光谱中羧酸酯基团的对称和不对称拉伸频率的分析显示出单齿键合模式。如粉末 X 射线衍射 (PXRD) 数据所示,以无定形状态获得化合物。获得的结果验证了使用 TG 曲线进行的质量损失分配。然而,气体产物分析表明降解过程比单独的热分析技术更复杂。本研究使用 GC-MS 技术来鉴定在吡啶甲酸酯复合物热降解的第二步中获得的冷凝气态产物。红外光谱中羧酸酯基团的对称和不对称拉伸频率的分析显示出单齿键合模式。如粉末X射线衍射(PXRD)数据所示,以无定形状态获得化合物。获得的结果验证了使用 TG 曲线进行的质量损失分配。然而,气体产物分析表明降解过程比单独的热分析技术更复杂。本研究使用 GC-MS 技术来鉴定在吡啶甲酸酯复合物热降解的第二步中获得的冷凝气态产物。红外光谱中羧酸酯基团的对称和不对称拉伸频率的分析显示出单齿键合模式。如粉末 X 射线衍射 (PXRD) 数据所示,以无定形状态获得化合物。本研究使用 GC-MS 技术来鉴定在吡啶甲酸酯复合物热降解的第二步中获得的冷凝气态产物。红外光谱中羧酸酯基团的对称和不对称拉伸频率的分析显示出单齿键合模式。如粉末X射线衍射(PXRD)数据所示,以无定形状态获得化合物。本研究使用 GC-MS 技术来鉴定在吡啶甲酸酯复合物热降解的第二步中获得的冷凝气态产物。红外光谱中羧酸酯基团的对称和不对称拉伸频率的分析显示出单齿键合模式。如粉末 X 射线衍射 (PXRD) 数据所示,以无定形状态获得化合物。
更新日期:2019-11-01
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