Neodymium β-diketonate showing slow magnetic relaxation and acting as a ratiometric thermometer based on near-infrared emission

Abstract

Self-assembly of b-diketonate (Htta ¼ thenoyl(trifluoro)acetone) and 4,4 0 -azopyridine (Azo-py) with neodymium(III) ions in the presence of methanol resulted in the formation of mononuclear complex [Nd III (TTA) 3 (MeOH) 2 ]$0.5Azo-py (A) in which two asymmetric units are linked by Azo-py through hydrogen bonding via methanol. A reveals near-infrared emission (NIR) centred at about 895 and 1056 nm, in the 10-370 K temperature range, originating from the two emissive transitions on Nd(III) from 4 F 3/2 to 4 I 9/2 and 4 I 11/2 levels, respectively. Furthermore, the NIR luminescence intensity of A at room temperature augments two times upon thermal elimination of one coordinated methanol molecule. The thermally activated A exhibits single centre ratiometric thermometer behaviour in a wide temperature range from 10 to 300 K. Moreover, fluorescence properties of A were compared to another mononuclear complex [Nd III (TTA) 3 (4-OHpy)(H 2 O)] (B). Assembly A also exhibits field-induced slow magnetic relaxation properties with an energy barrier of DE/k B ¼ 19.7(7) K and an attempt time of relaxation, s 0 ¼ 3.7(8) Â 10 À7 s for fresh sample A, and DE/k B ¼ 27.3 K and s 0 ¼ 8.5(0) Â 10 À8 for assembly A after thermal treatment at 370 K.

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

“…The observed maximum sensitivity is 0.207% K −1 for 1-S, corresponding to Δ (1060/874) at 300 K and 0.207% K −1 for 1-Se at 170 K related to Δ (895/874). These sensitivity parameters are comparable to oxide-based thermometers in which the Nd 3+ ion is embedded in various oxides and they are higher than previously reported complexes [ 56 , 57 ]. The transition Δ (1060/874) emanates from the non-coupled 4 F 3/2(1) excited level, unlike other thermometric parameters, as a result of which the Mott–Seitz model (Equation (S1)) is also used to examine the thermometric data ( Figure 5 g, Tables S6 and S7 ).…”

Proton Conductive Luminescent Thermometer Based on Near-Infrared Emissive {YbCo2} Molecular Nanomagnets

“…In this respect, 4f-metal-based materials were used in display devices, light-emitting diodes, optical storage, sensing, and bioimaging. − Moreover, they are used in up-conversion luminescence materials, and luminescent molecular thermometers for the detection of temperature at the nanoscale. − The combination of both luminescence and slow magnetic relaxation has lately become an emerging topic . Thus, white-light-emitting, , multicolored-, and NIR-emissive molecular nanomagnets were obtained, − and the correlations between magnetic anisotropy and luminescence, both originating from the electronic structure of 4f metal ions, were reported. − Recently, the impact of solvation-driven phase transformation upon both properties in porous magnets was investigated, , while a slow magnetic relaxation in luminescent thermometers appeared as an avenue for novel opto-magnetic devices. − …”

Holmium(iii) molecular nanomagnets for optical thermometry exploring the luminescence re-absorption effect

“…28 Recently, a research pathway consisting of the application of lanthanide SMMs in the construction of luminescent molecular thermometers emerged. [29][30][31][32][33][34] Optical thermometry utilizing thermally activated luminescence of f-block metal ions was broadly investigated in the last decade [35][36][37][38][39] as it opens the avenue to contactless temperature sensors for electronic devices, 40 medical diagnostics, 41 or chemical reactors. 42 The molecular approach is particularly attractive due to the sensing ability at the nanoscale.…”

“…[40][41][42][43] When combining this property with the SMM effect, multifunctional magnetic luminescent thermometers are accessible. [29][30][31][32][33][34] They can realize a multitasking concept, 33,44 and they are promising building blocks for smart electromagnetic SMM-based devices with a self-monitored temperature. 29 Achieving optical thermometers using lanthanide SMMs demands the simultaneous design of magnetic anisotropy and thermally modulated emission.…”

“…This challenging task was realized by applying intrinsic properties of Dy III or Yb III complexes. [29][30][31][32][33][34] The Dy III centres reveal very strong magnetic anisotropy, 45 but their yellow luminescence is relatively weak, hampering the utility for optical thermometry. 46,47 Interest was also devoted to Yb III due to its efficiently modulated NIR emission.…”