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Game of Crowns: Na+ Is Coming! Red NIR-Emissive Hybrid Liquid Crystals Containing Discotic Crown Ethers and Na2Mo6X8iCl6 (Xi = Cl or Br)
journal contributionposted on 2023-08-11, 15:35 authored by Irene Carrasco, Philipp Ehni, Max Ebert, Noée Dumait, Gregory Taupier, Maria Amela-Cortes, Claire Roiland, Stéphane Cordier, Julius A. Knöller, Emmanuel Jacques, Sabine Laschat, Yann Molard
Molecular or supramolecular materials that can self-organize into columns such as discotic liquid crystals are of interest for several applications in the field of optoelectronics. We show in this work that red near-infrared (NIR)-emissive metal cluster compounds of general formula Na2Mo6X8iCl6 (Xi = Cl or Br) can be readily complexed with discotic liquid crystals containing a crown ether. Three cavity sizes have been tested with crown ethers bearing 4, 5, or 6 oxygen atoms. In all cases, 1:1 complexes were formed, thanks to the well-known supramolecular interactions existing between the Na+ cations of the metal cluster salt and the crown ether derivatives. All obtained hybrids are homogeneous, emit in the red NIR region, and show liquid crystalline properties on a wider temperature range than their precursors. Charge transport properties have been investigated by using a space charge limited current device. Obtained results demonstrate that metal cluster compounds can enhance the charge carrier mobility by 5 orders of magnitude compared to the native discotic organic ligands. Considering that the presented organic crown ether derivatives are not the best candidates to design optoelectronic devices because of their inherently low conductivity, but that similar compounds were developed to design proton conductive porous framework, our results open promising perspectives for the use of metal cluster compounds in devices dedicated to such a field.
wider temperature rangethree cavity sizesmetal cluster saltinherently low conductivitydiscotic liquid crystalscharge transport propertiescharge carrier mobility6 oxygen atomsobtained results demonstratemetal cluster compoundsdesign optoelectronic devicesgeneral formula nacrown ether derivatives6 sub2 subred nir regionsup >+ supcrown ether supred nirsimilar compoundsobtained hybridsdevices dedicatedred nearsupramolecular materialsseveral applicationsreadily complexedmagnitude comparedbest candidates