Luminescent fluorinated chiral liquid crystalline oligomers containing Eu(III) complexes

ABSTRACT

Luminescent fluorinated chiral liquid crystalline oligomers containing Eu(III) complexes (Eu-LCOs) with good liquid crystalline properties and obvious luminescence properties were prepared using Poly(methylhydrogeno)siloxane (PMHS), chiral liquid crystalline monomer (M₁), fluorinated liquid crystalline monomer (M₂), fluorinated Eu(III) complex (M₃). The chemical structures, liquid crystalline behaviours of Eu-LCOs were characterised by various experimental techniques. The introduction of small quantity of fluorinated Eu(III) complexes endowed the oligomers with excellent luminescence properties. The Eu(III) complexes did not change the liquid crystalline textures of the oligomers. Fourier transform infrared imaging showed that Eu(III) complexes were evenly distributed in oligomers. In order to express the mutual effect and distribution of the components, a structural representation of Eu-LCOs was established. The Eu-LCOs displayed wide mesophase temperature ranges and reversible mesomorphic phase transitions. The Eu-LCOs can emit soft red light when being excited. Luminescence intensities of Eu-LCOs gradually increased with an increase of Eu(III) complexes from 0 to 1.0 mol%. However, the luminescence intensities of Eu-LCOs decreased monotonically with the increase of temperature in liquid crystalline phase.

Graphical Abstract

KEYWORDS:

• Liquid crystalline
• oligomers
• europium
• fluorescence

Disclosure statement

No potential conflict of interest was reported by the authors.

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Funding

The authors are grateful to the Xuzhou University of Technology Youth Program [contract grant number XKY2016219, XKY2016218] and the Natural Science Foundation of Jiangsu Province [contract grant number SK20171168] for financial support of this work.