【摘要】 合成了稀土Eu3+,Tb3+冠醚、对苯二甲酸高氯酸盐两个系列18种固态配合物。结果表明,配合物的组成为:Eu2LL′2(ClO4)4.4H2O、EuReLL′2(ClO4)4.nH2O、Tb2LL′2(ClO4)4.4H2O和TbReLL′2(ClO4)4.nH2O(Re:掺杂离子,n=2,3,4)。对苯二甲酸的羧基氧与稀土离子以对称螯合双齿配位;部分高氯酸在内界以单齿配位;配合物含有水分子。配合物的相对荧光光谱测定表明,相同配体的铽系列配合物的荧光强度明显强于铕系列。稀土离子Eu3+的5D0能级为17250cm-1,Tb3+的5D4能级为20430cm-1,而配体对苯二甲酸的三重态能级为25160cm-1,高于Eu3+和Tb3+离子的激发态能级,满足配合物分子内传能配体的三重态能级高于稀土离子发射能级的条件,可以提高Eu3+和Tb3+离子的特征荧光强度。但相对于Eu3+离子,对苯二甲酸的三重态能级与Tb3+离子的激发态能级(5D4)更匹配,更有利于能量的有效传递,因此,铽系列的荧光强度明显强于铕系列。Ho3+、Yb3+对Eu3+离子发光敏化作用最强,Ce3+、Sm3+、Dy3+、Er3+对Eu3+离子发光也有敏化作用,Pr3+、Nd3+离子对Eu3+离子的发光是猝灭的;Yb3+、Dy3+离子对Tb3+离子发光有较强敏化作用,而Ce3+、Pr3+、Nd3+、Sm3+、Ho3+、Er3+离子的掺入对Tb3+离子的发光是猝灭的。应用分子内能量传递过程对发光机理进行了探讨。更多还原

【Abstract】 Two series of Eu3+,Tb3+ heteronuclear doped complexes with terephthalic acid(L) and 18-crown-6(L’) have been synthesized.Elemental analysis,IR,UV absorption spectra,rare earth complexometry and fluorescence spectra have been studied respectively.The compositions of the complexes were confirmed to be EuRELL’2(ClO4)4·nH2O and TbRELL’2(ClO4)4·nH2O(RE=Ce3+,Pr3+,Nd3+,Sm3+,Eu3+,Tb3+,Dy3+,Ho3+,Er3+,Yb3+;n=2,3,4).Terbium series complexes show that there is an excitation characteristic peak,which is a wide band from 230 to 340 nm,and a maximum peak is at 300 nm.To europium series complexes the band from 220 to 330 nm and maximum peak is at 261 nm.The excitation characteristic peaks are assigned to the ligands-metal energy transfer band through —COO—RE—OOC—.So 300 nm and 261 nm were chosen as excitation wavelength respectively to measure the fluorescence spectra of europium and terbium complexes.We all know that the UV absorption of 18-C-6 is weak,the 5D0 energy of Eu3+is 17 250,but 20 430 cm-1 for the 5D4 energy of Tb3+,and 25 160 cm-1 for the triplet energy of terephthalic acid.The triplet energy of terephthalic acid is higher a little than the excitation energy of Tb ion,but more higher than Eu3+ ion’s,the lowest excitation energy of Tb3+ ion matchs well with the triplet state energy of the ligand each other.Thus it is possible that energy transfer from terephthalic acid ligand to Tb3+ through —COO—RE—OOC— bonds more effectively.Absorbing energy of organic ligands are effectively transfered to the rare earth ion in the luminescence center,and producing a characteristic spectrum.Some non-fluorescence rare earth ions can absorb the energies of triplet organic ligand too,and then transfer them to Eu3+or Tb3+,in this way the fluorescence intensity was enhanced.If the transition energy of non-fluorescence rare earth ions is lower than the 5D4 energy of Tb3+ or 5D0 energy of Eu3+,the luminescence will be quenched.Another way,the high-energy vibration of the OH of H2O molecules will heavily quench the luminescence of RE ions,so 18-crown-6 was introduced to replace some coordination H2O molecular.These results will provide relatively reliable criteria for the prediction of luminescence properties of rare earth complexes and for seeking excellent luminescent materials.更多还原