Synthesis, characterization and photophysical properties of three novel lanthanide materials

Abstract

Three new lanthanide compounds with different structures, i.e. [Tb(2,6-naphthalenedisulfonic acid)(OH)(H2O)2]n (1), [Nd(HIA)2(NO3)(H2O)3]n2n(NO3)·nH2O (2; HIA = isonicotinic acid) and [Er6(H2O)12(NO3)6(OH)8(O)]2NO3·2H2O (3), were obtained from hydrothermal reactions. Their crystal structures were characterized with single-crystal X-ray diffraction. Compound 1 is characteristic of a two-dimensional (2-D) layer-like structure, compound 2 features a one-dimensional (1-D) chain-like structure, while compound 3 shows an isolated (0-D) Er6 hexanuclear structure. The solid-state UV/Vis diffuse reflectance spectra show that the semiconductor bandgaps are 2.89 eV, 3.12 eV and 4.64 eV for compounds 1, 2 and 3, respectively. The solid-state photoluminescent measurements exhibit that they can show green, red and blue emissions. These photoluminescence emissions are originated from the characteristic emissions of the 4f electron intrashell transitions of the 5D4 → 7F6 of the Tb3+ ions in compound 1, the 4F7/2 → 4S3/2 of the Nd3+ ions in compound 2 and the 4F9/2 (4F5/2) → 4I15/2 of the Er3+ ions in compound 3. Their CIE (Commission Internationale de I'Éclairage) chromaticity coordinates are (0.2451, 0.4041), (0.7334, 0.2666) and (0.1391, 0.0483). Their CCT (Correlated Color Temperature) are 8937 K, 400,100 K and 2654 K.