Two novel Eu3+ complexes Eu(CDBM)3·2H2O and Eu(CCDBM)3·2H2O have been synthesized (CDBM = 1-(4-(9-carbazol)phenyl)-3-phenyl-1,3-propanedione, CCDBM = 1-((4-(9-carbazol)methyl)phenyl)-3-phenyl-1,3-propanedione). Eu(CDBM)3·2H2O showed strong internal ligand charge transfer (ILCT) fluorescence and sensitized emission of Eu3+. Due to the charge transfer character, the fluorescence band of CDBM shifted from 403 nm in cyclohexane to 559 nm in acetonitrile. Photophysical studies demonstrated that no energy was migrated from the ILCT excited state of the ligands to Eu3+, and that Eu3+ was sensitized by the triplet state which was localized in the 1,3-diphenyl-1,3-propanedione (DBM) part. The quantum efficiencies of Eu3+ in the three complexes are in the order Eu(DBM)3·2H2O > Eu(CCDBM)3·2H2O > Eu(CDBM)3·2H2O in both solution and the solid state. The energy transfer pathways in the three Eu3+ complexes were discussed in detail. Based on the systematic photophysical studies, a new guideline for the organo-lanthanide light emitting materials has been proposed: ILCT should be avoided during molecular modification.
合成了两种新型 Eu3+ 复合物 Eu(C
DBM)3Â-2H2O 和 Eu(CC
DBM)3Â-2H2O(C
DBM = 1-(4-(9-
咔唑)苯基)-3-苯基-1,3-丙二酮,CC
DBM = 1-((4-(9-
咔唑)甲基)苯基)-3-苯基-1,3-丙二酮)。Eu(C
DBM)3Â-2H2O 显示出强烈的内部
配体电荷转移(ILCT)荧光和 Eu3+ 的敏化发射。由于电荷转移的特性,C
DBM 的荧光带从
环己烷中的 403 纳米移至
乙腈中的 559 纳米。光物理研究表明,
配体的 ILCT 激发态没有能量迁移到 Eu3+,Eu3+ 被三重态敏化,三重态位于 1,3
-二苯基-1,3-丙二酮(
DBM)部分。三种复合物中 Eu3+ 的量子效率在溶液和固态中的顺序为 Eu(
DBM)3Â-2H2O > Eu(CC
DBM)3Â-2H2O > Eu(C
DBM)3Â-2H2O。详细讨论了三种 Eu3+ 复合物的能量转移途径。基于系统的光物理研究,提出了有机
镧系
发光材料的新准则:在分子修饰过程中应避免 ILCT。