Development of Nd (III)-Based Terahertz Absorbers Revealing Temperature Dependent Near-Infrared Luminescence

Abstract

Molecular vibrations in the solid-state, detectable in the terahertz (THz) region, are the subject of research to further develop THz technologies. To observe such vibrations in terahertz time-domain spectroscopy (THz-TDS) and low-frequency (LF) Raman spectroscopy, two supramolecular assemblies with the formula [NdIII (phen)3 (NCX)3] 0.3EtOH (X = S, 1-S; Se, 1-Se) were designed and prepared. Both compounds show several THz-TDS and LF-Raman peaks in the sub-THz range, with the lowest frequencies of 0.65 and 0.59 THz for 1-S and 1-Se, and 0.75 and 0.61 THz for 1-S and 1-Se, respectively. The peak redshift was observed due to the substitution of SCN- by SeCN-. Additionally, temperature-dependent TDS-THz studies showed a thermal blueshift phenomenon, as the peak position shifted to 0.68 THz for 1-S and 0.62 THz for 1-Se at 10 K. Based on ab initio calculations, sub-THz vibrations were ascribed to the swaying of the three thiocyanate/selenocyanate. Moreover, both samples exhibited near-infrared (NIR) emission from Nd (III), and very good thermometric properties in the 300–150 K range, comparable to neodymium (III) oxide-based thermometers and higher than previously reported complexes. Moreover, the temperature dependence of fluorescence and THz spectroscopy analysis showed that the reduction in anharmonic thermal vibrations leads to a significant increase in the intensity and a reduction in the width of the emission and LF absorption peaks. These studies provide the basis for developing new routes to adjust the LF vibrational absorption.

Low‐Frequency Sub‐Terahertz Absorption in HgII−XCN−FeII (X=S, Se) Coordination Polymers

“…The redshift of 4‐Se is attributed to the larger motion freedom in the 2D structure compared with the 3D structures of 3 and 3‐Se . These results agree well with the previously reported observations for complexes A I [Co II (3‐CNpy) 2 ][W V (CN) 8 ], [12b] [Yb III (TPPO) 3 (NCX) 3 ], [14a] and [Nd III (1,10‐phen) 3 (NCX) 3 ]⋅0.3 EtOH, [14b] where A=Cs or Rb, X=S or Se, and TPPO=triphenylphosphine oxide. Because other factors may influence the observations, further research is necessary.…”

Slow magnetic relaxation in Nd(iii) and Sm(iii) complexes formed in three-dimensional lanthanide-dicyanidometallate(i) frameworks exhibiting luminescent properties

“…Research and development in the field of three-dimensional (3D) coordination polymers, such as metal-organic frameworks (MOFs), [1][2][3] Prussian blue analogues (PBAs), [4][5][6][7] other inorganic networks, [8][9][10] and hybrid inorganic-organic coordination polymers, [8][9][10][11] laid the foundations for the advancement of multifunctional materials exhibiting non-trivial magnetic properties (e.g., long-range magnetic ordering, spin-crossover), [12][13][14] luminescence, [15][16][17][18][19] proton conductivity 20 and nonlinear optics phenomena. [21][22][23] Such high-dimensional systems captured the attention of material scientists and engineers as promising platforms for the construction of diverse telecommunication, optical storage, and spintronic devices, as well as optical thermometers.…”