Long-lived luminescent soft materials of hexanitratosamarate(iii) complexes with orange visible emission

Abstract

Sm(III)-based ionic liquids incorporating hexanitratosamarate(III) anions were obtained and fully characterized as novel Sm(III)-containing organic complexes. The structure of the ionic liquids was determined by single-crystal X-ray diffraction (1: monoclinic system C2/c space group with cell parameters: a = 19.5624(4) Å, b = 10.11895(18) Å, c = 33.2256(6) Å, β = 101.2912(18)°, Z = 8). The central Sm(III) ion is 12-coordinated by six bidentate nitrate ligands with twelve oxygen donors to form a [Sm(NO₃)₆]³⁻ anion. The low melting point, high thermostability and wide liquid range of these ionic liquids were determined in detail. All the complexes 1–5 display orange luminescence, rather than red luminescence as in most Sm(III)-containing organic complexes. Three characteristic monochromatic bands and an intense emission, derived from ⁴G_5/2→⁶H_J (J = 5/2, 7/2, and 9/2) intraconfigurational f–f transitions, were revealed. All these complexes exhibit long luminescence lifetimes.