Alzard Reem H, Siddig Lamia A, Saleh Na'il, Nguyen Ha L, Nguyen Quynh Anh T, Ho Thi H, Bui Viet Q, Sethupathi K, Sreejith P K, Alzamly Ahmed
Department of Chemistry, UAE University, P.O. Box 15551, Al-Ain, UAE.
Department of Chemistry, University of California Berkeley, Berkeley, CA, 94720, USA.
Sci Rep. 2022 Nov 5;12(1):18812. doi: 10.1038/s41598-022-23658-z.
Two lanthanide metal-organic frameworks [Ln-MOFs, Ln = Eu(III), Tb(III)] composed of oxalic acid and Ln building units were hydrothermally synthesized and fully characterized by powder X-ray diffraction, Fourier-transform infrared spectroscopy, thermogravimetric analysis, scanning electron microscope, and energy-dispersive X-ray spectroscopy. Furthermore, their magnetic susceptibility measurements were obtained using SQUID based vibrating sample magnetometer (MPMS 3, Quantum Design). Both Ln-MOFs exhibited highly efficient luminescent property. Solid-state photoluminescence (PL) measurements revealed phosphorescence emission bands of Eu-MOF and Tb-MOF centered at 618 nm (red emission) and 550 nm (green emission) upon excitation at 396 nm and 285 nm, respectively. Eu-MOF and Tb-MOF displayed a phosphorescence quantum yield of 53% and 40%, respectively. Time-resolved PL analyses showed very long lifetime values, at 600 and 1065 ± 1 µs for Eu-MOF and Tb-MOF, respectively. Calculations performed by density functional theory indicated a charge transfer form metal centres to the ligand which was in good agreement with the experimental studies. Therefore, this new mode of highly photoluminescent MOF materials is studied for the first time which paves the way for better understanding of these systems for potential applications.
通过水热法合成了两种由草酸和镧系元素构筑单元组成的镧系金属有机框架材料[Ln-MOFs，Ln = Eu(III)，Tb(III)]，并通过粉末X射线衍射、傅里叶变换红外光谱、热重分析、扫描电子显微镜和能量色散X射线光谱对其进行了全面表征。此外，使用基于超导量子干涉仪的振动样品磁强计（MPMS 3，Quantum Design）对它们进行了磁化率测量。两种Ln-MOFs均表现出高效的发光性能。固态光致发光（PL）测量表明，在分别以396 nm和285 nm激发时，Eu-MOF和Tb-MOF的磷光发射带分别位于618 nm（红色发射）和550 nm（绿色发射）处。Eu-MOF和Tb-MOF的磷光量子产率分别为53%和40%。时间分辨PL分析显示，Eu-MOF和Tb-MOF的寿命值非常长，分别为600和1065±1 μs。密度泛函理论计算表明存在从金属中心到配体的电荷转移，这与实验研究结果吻合良好。因此，首次对这种新型的高光致发光MOF材料进行了研究，为更好地理解这些体系的潜在应用铺平了道路。
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