posted on 2023-08-11, 15:35authored byIrene 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.