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Published on: April 16, 2017
Chiroptical Activity of An Achiral Emissive Eu Metal-Organic Framework
Yuan Li1, Xiaojie Ma1, Xiaojun Xu1
1Beijing Key Laboratory of Photoelectronic/, Electrophotonic Conversion Materials, Key Laboratory of Cluster Science, Ministry of Education, Advanced Technology Research Institute (Jinan), School of Chemistry and Chemical Engineering, Beijing Institute of Technology, No. 5, South Street, Zhongguancun Haidian District, Beijing, 100081, P. R. China.
Abstract:
Chiroptical activity of achiral crystals is theoretically allowed but very unusual. There is a particularly scarcity of empirical studies on optically active achiral metal-organic frameworks (MOFs). Herein we report an achiral emissive Eu MOF and its chiroptical properties both in the ground and excited states. The framework crystallizes in an achiral space group (Pna21 ) belonging to the polar point group (mm2), where the asymmetric arrangement of racemic trinuclear Eu-oxo clusters is responsible for the optical activity. A pair of circular dichroisms (CD) and circularly polarized luminescence (CPL) peaks with opposite signs were observed for single crystals. Importantly, the luminescence dissymmetry factor can reach up to 1.1×10-3 , which is comparable in magnitude to the value of most of the chiral-linker-bridged MOFs. This work gives the first example of achiral MOFs with CPL response and should be instructive for the discovery of more CPL emitters from racemic MOF family.
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