摘要
合成了Tb(Trp) 3Cl3·H2 O、Dy(Trp) 3Cl3·H2 O和Ho(Trp) 3Cl3·H2 O固态配合物 ,在30 0～ 80 0nm测定并解释了配合物的光声光谱 ,从无辐射跃迁角度研究色氨酸固态配合物的能级状况和分子内能量传递过程 ,结合荧光光谱研究了色氨酸固态配合物的发光特性 ,结果表明固态配合物中色氨酸配体可有效敏化Tb3+离子的发光 ,而由于热去几率速率增大导致配体向Dy3+的能量传递效率降低 .首次将相位分辨光声分析法用于Ho(Trp) 3Cl3·H2 O配合物的谱峰解析 ,通过光声谱同相和正交相信号可以计算配体光声吸收的位相为 10 6° ,位相改变 90°后就得到仅与Ho3+相关的光声光谱 .相位分辨光声光谱法不受谱峰的形状和重叠程度的限制 。
The crystals of Tb(Trp) 3Cl 3·H 2O, Dy(Trp) 3Cl 3·H 2O and Ho(Trp) 3Cl 3·H 2O are synthesized. At the room temperature photoacoustic spectra (PA) of these complexes are recorded and interpreted in the region of 300～800 nm. The PA band of the title complexes in the region of 310 nm, which is assigned to the π-π * transition of tryptophan, is significantly stronger than that of the free_base Trp. This is due to the fact that the π electron conjugated system of the title complexes is much larger than that of the free_base Trp and has a higher molar absorptivity. The PA intensities of central rare earth ions are interpreted by the probability of nonradiative transitions. It is found that the PA intensity of the ligand bears a relation to the intramolecular energy transfer process. In the region of ligand absorption, PA intensity decreases for Ho(Trp) 3Cl 3·H 2O, Dy(Trp) 3Cl 3·H 2O and Tb(Trp) 3Cl 3·H 2O respectively. The change of fluorescence spectra turns out to be complementary to the PA spectra. The results are interpreted by Dexter theory. For Dy(Trp) 3·H 2O complex, the energy difference between the ligand triplet state and the resonance level 5D 4 of the central ion is too small, and the energy transfer is not efficient because of the thermal deexcitation process. In the case of Tb(Trp) 3Cl 3·H 2O, the energy difference between the triplet state and the resonance level 5D 4 of Tb 3+ is about 2.5×10 3 cm -1 , which is appropriate for energy transfer, and the energy transfer is very efficient. It can be concluded that it is essential that the triplet state of the ligand be higher than the resonance level of the central rare earth ions for which leads to the occurence of efficient energy transfer. The energy transfer will decrease when the energy difference is small because of the thermal deexcitation process. The relaxation process models are also studied on the basis of the PA and fluorescence spectra. PA phase_resolved method is used to separate the overlapping peaks of Ho(Trp) 3Cl 3·H 2O for the first time. PA peaks of Ho 3+ are covered completely by the absorption of tryptophan(Trp) in the region of 300～400 nm. In the PA spectrum,the phase angle of Trp(106 o) is calculated according to the in_phase and out_of_phase signals. Only the contribution of Ho 3+ can be observed when the phase angle equals 16 o. PA peaks of Ho(Trp) 3Cl 3·H 2O are separated well within 300～400 nm. PA phase_resolved method has the advantage to interpret the spectrum based on different phase angles, and is free from the overlapping of different absorption bands.
出处
《南京大学学报（自然科学版）》
CAS
CSCD
北大核心
2002年第4期499-504,共6页
Journal of Nanjing University（Natural Science）
基金
国家自然科学基金 (10 174 0 38)
