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The rare earth complexes Tb(o-BrBA)3,Tb(m-BrBA)3 and Tb(p-BrBA)3 were synthesized using o-,m-,p-bromo benzoic acids(2-bromo benzoic acid,3-bromo benzoic acid and 4-bromo benzoic acid) as ligand,respectively.The UV spectra showed that the absorption ability of Tb(m-BrBA)3 was the strongest.However,the fluorescent intensity of Tb(o-BrBA)3 was the weakest.The effect of the molecular structure,the energy level of Tb3+ and energy transfer efficiency from ligands to Tb3+ were discussed to explain the experimental results.The results indicated that,due to the large atomic radius of bromine,the steric effect caused by the different substitution bromine on the benzene ring might strongly affect the bond length formed by the coordination atoms and Tb3+.The longer the bond length was,the lower the efficiency of energy transfer was,and the weaker the fluorescent intensity was. 相似文献
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采用溶胶-凝胶法制备了Yb掺杂TiO2纳米光催化剂,并通过XRD和BET等手段进行了表征.以对苯二甲酸作为探针分子,结合化学荧光技术研究了光催化剂表面羟基自由基的生成;并以苯酚为光催化降解反应模型化合物,考察了光催化剂的活性.测定了苯酚在TiO2和Yb掺杂TiO2光催化剂上的吸附常数.结果表明:Yb掺杂使TiO2的粒径减小,比表面积增大,同时导致羟基自由基的生成速率增大.Yb掺杂有利于反应底物在催化剂表面的吸附,Yb的最佳掺入量为Yb/Ti摩尔比=0.8%. 相似文献
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以甲苯为原料,经过磺化、酰氯化反应合成4-甲基苯磺酰氯。该工艺与传统合成工艺相比,具有原料消耗低,产品收率高,纯度高,选择性高,成本低等优点,具有广阔的工业化应用前景。 相似文献