ANTENNA EFFECT IN LUMINESCENT LANTHANIDE CRYPTATES - A PHOTOPHYSICAL STUDY
ANTENNA EFFECT IN LUMINESCENT LANTHANIDE CRYPTATES - A PHOTOPHYSICAL STUDY
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DOI：
10.1111/j.1751-1097.1990.tb04185.x
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发表时间：
1990-08-01
影响因子：
3.3
通讯作者：
SABBATINI, N
中科院分区：
文献类型：
--
作者：
ALPHA, B;BALLARDINI, R;SABBATINI, N
对笼型隐态配合物进行了激发态发射和吸收衰减测量[M . cnnd]。bpy.bpy。[bpy.bpy]n+，其中Mn+ = Na+, La3+, Eu3+， Gd3+或Tb3+；Bpy]是一个三联吡啶大双环密码体。在高强度下进行了激发。*密码带，最大约300 nm。在水或D2O溶液和300和77 K下进行了实验，计算了辐射和非辐射衰变过程的速率常数。对于Mn+ = Na+， La3+和Gd3+，密码态的最低激发态为3. .pi。在室温的H2O溶液中以微秒时间尺度衰变，在77 K的MeOH-EtOH中以秒毫秒时间尺度衰变。对于Mn+ = Eu3+，最低激发态是发光的5D0 Eu3+能级，在H2O溶液中以10%的效率填充，以2.9倍的速率衰减到基态。在室温下103 s-1和1.2倍。103s -1, 77k。在1. .. .. .. .*激发归因于配体到金属的电荷转移能级的存在，通过该能级，1.…*直接衰减到基态。对于Mn+ = Tb3+，最低激发态是发光的5D4 Tb3+能级。5D4在1圆周率…圆周率。*激励为。apprx。100%的效率，但在室温下，随之而来的是从5D4 Tb3+能级到3.…*配体水平，因为两个能级之间的能量差距相对较小（1200 cm-1）和5D4本质上的长寿命。在77 K时，不能发生反向能量转移，5D4 Tb3+能级失活到基态，速率常数为5.9倍。102 S-1 （H2O溶液）。讨论了这些结果与Eu3+和Tb3+隐泡体作为发光探针的优化的相关性。
Excited state emission and absorption decay measurements have been made on the cage-type cryptate complexes [M .cntnd. bpy.bpy.bpy]n+, where Mn+ = Na+, La3+, Eu3+, Gd3+ or Tb3+ and [bpy.bpy.bpy] is a tris-bipyridine macrobicyclic cryptand. Excitation has been performed in the high intensity 1.pi..pi.* cryptand band with maximum at about 300 nm. Experiments have been carried out in H2O or D2O solutions and a 300 and 77 K to evaluate the rate constants of radiative and nonradiative decay processes. For Mn+ = Na+, La3+ and Gd3+ the lowest excited state of the cryptate is a 3.pi..pi.* level of the cryptand which decays in the microsecond time scale at room temperature in H2O solution and in the second-millisecond time scale at 77 K in MeOH-EtOH. For Mn+ = Eu3+, the lowest excited state is the luminescent 5D0 Eu3+ level which in H2O solution is populated with 10% efficiency and decays to the ground state with rate constants 2.9 .times. 103 s-1 at room temperature and 1.2 .times. 103 s-1 at 77 K. The relatively low efficiency of 5D0 population upon 1.pi..pi.* excitation is attributed to the presence of a ligand-to-metal charge transfer level through which 1.pi..pi.* decays directly to the ground state. For Mn+ = Tb3+ the lowest excited state is the luminescent 5D4 Tb3+ level. The process of 5D4 population upon 1.pi..pi.* excitation is .apprx.100% efficient, but at room temperature it is followed by a high-efficiency, activated back energy transfer from the 5D4 Tb3+ level to the 3.pi..pi.* ligand level because of the relatively small energy gap between the two levels (1200 cm-1) and the intrinsically long lifetime of 5D4. At 77 K back energy transfer cannot take place and the 5D4 Tb3+ level deactivates to the ground state with rate constant 5.9 .times. 102 S-1 (H2O solution). The relevance of these results toward the optimization of Eu3+ and Tb3+ cryptates as luminescent probes is discussed.