Blue Excitement: The Lanthanide(III) Chloride Oxidomolybdates(VI) Ln3Cl3[MoO6] (Ln = La, Pr, and Nd) and Their Spectroscopic Properties

Katharina V Dorn; Björn Blaschkowski; Philip Netzsch; Henning A Höppe; Ingo Hartenbach

doi:10.1021/acs.inorgchem.9b00098

Blue Excitement: The Lanthanide(III) Chloride Oxidomolybdates(VI) Ln₃Cl₃[MoO₆] (Ln = La, Pr, and Nd) and Their Spectroscopic Properties

Inorg Chem. 2019 Jul 1;58(13):8308-8315. doi: 10.1021/acs.inorgchem.9b00098. Epub 2019 Jun 19.

Authors

Katharina V Dorn^{1

2}, Björn Blaschkowski¹, Philip Netzsch³, Henning A Höppe³, Ingo Hartenbach¹

Affiliations

¹ Institute of Inorganic Chemistry , University of Stuttgart , Pfaffenwaldring 55 , 70569 Stuttgart , Germany.
² Department of Materials and Environmental Chemistry , Stockholm University , Svante Arrhenius väg 16 C , 106 91 Stockholm , Sweden.
³ Institute of Physics , University of Augsburg , Universitätsstraße 1 , 86159 Augsburg , Germany.

PMID: 31247851
DOI: 10.1021/acs.inorgchem.9b00098

Abstract

The lanthanide(III) chloride oxidomolybdates(VI) with the empirical formula Ln₃Cl₃[MoO₆] (Ln = La, Pr, and Nd) were synthesized by solid-state reactions utilizing the respective lanthanide trichloride, lanthanide sesquioxide (where available), and molybdenum trioxide together with lithium chloride as a fluxing agent. The title compounds crystallize in hexagonal space group P6₃/ m ( a = 942-926 pm, c = 542-533 pm, Z = 2). Besides tetracapped trigonal prismatically coordinated Ln³⁺ cations, noncondensed trigonal prismatic [MoO₆]^6- entities are found in the crystal structure. In addition to X-ray diffraction, the title compounds were also characterized by single-crystal Raman and infrared spectroscopy as well as measurements to determine their magnetic susceptibility and behavior at low temperatures. The most outstanding properties of the Ln₃Cl₃[MoO₆] representatives (Ln = La, Pr, and Nd), however, are of an optical nature, because their band gaps, determined by diffuse reflectance spectroscopy, show a significant shift toward lower energies compared to those of other rare-earth metal chloride molybdates with a different polyhedral arrangement. This culminates in La₃Cl₃[MoO₆]:Eu³⁺ exhibiting luminescence, which can be excited in the visible range of the electromagnetic spectrum by a blue light-emitting diode.