期刊
CHEMISTRY OF MATERIALS
卷 25, 期 4, 页码 586-598出版社
AMER CHEMICAL SOC
DOI: 10.1021/cm303776x
关键词
Eu3+ and Gd3+ complexes; trans-to-cis photoisomerization; trans-1,2-bis(4-pyridyl)ethylene; luminescence intensity and quantum yield enhancement; photostability mechanism; degradation under UV irradiation
资金
- Fundacao para a Ciencia e a Tecnologia (FCT, Portugal)
- COMPETE program
- FEDER program [Pest-C/CTM/LA0011/2011, PTDC/CTM/101324/2008, PTDC/CTMNAN/112168/2009]
- CNPq
- CAPES
- PRONEX-FACEPE-CNPq [APQ-0859-1.06/08]
- inct-INAMI (Brazil)
- Nanobiotec-CAPES network
- PPL [SFRH/BPD/34365/2006]
- MMN FCT [SFRH/BPD/32103/2006]
- Fundação para a Ciência e a Tecnologia [PTDC/CTM/101324/2008] Funding Source: FCT
Europium (t-Eu) and gadolinium (t-Gd) beta-diketonate complexes with photoactive t-bpete ligand, [Ln-(btfa)(3)(t-bpete)(MeOH)] (Ln = Eu, Gd), where btfa(-) and t-bpete are 4,4,4-trifluoro-1-phenyl-1,3-butanedionate and trans-1,2bis(4-pyridyl)ethylene, respectively, were synthesized, characterized by vibrational, absorption (reflectance) and photoluminescence spectroscopies and their crystal structure was determined using single-crystal X-ray diffraction. B3LYP calculations were performed to support the interpretation and rationalization of the experimental results. The complexes, under UV irradiation, do not display the typical photodegradation of the beta-diketonate ligands exhibiting, in turn, an unprecedented photostability during, at least, 10 h. During UV-A exposure (>330 nm), the emission intensities of both complexes increase drastically (similar to 20 times), whereas for t-Eu the emission quantum yield is enhanced at least 30 fold A mechanism based on a photoclick trans-to-cis isomerization of both t- and c-bpete moieties was proposed to explain the abnormal photostability of these compounds, either in solid state or in solution. The experimental and computational results are consistent with a photostationary state involving the trans-to-cis isomerization of the bpete ligand under continuous UV -A exposure, which thus diverts the incident radiation from other deleterious photochemical or photophysical processes that cause the typical photobleaching behavior of chelate lanthanide complexes. This shielding mechanism could be extended to other ligands permitting the design of new lanthanide-based photostable systems under UV exposure for applications in lighting, sensing, and displays.
作者
我是这篇论文的作者
点击您的名字以认领此论文并将其添加到您的个人资料中。
推荐
暂无数据