Ratiometric Raman and Luminescent Thermometers Constructed from Dysprosium Thiocyanidometallate Molecular Magnets

Abstract

Molecular crystals acting as temperature sensors, designed for multiple measurement techniques, can be a promising pathway for self‐calibrating thermometers. The molecular assemblies [DyxIIIY1–xIII(phen)2(μ‐OH)2(H2O)2]·[AuI(SCN)2]2·phen·0.5MeCN·0.5H2O (x = 0, 0.1, 0.02; phen = 1,10‐phenanthroline) which contain weakly bonded lanthanide(III) and Au(I) metal complexes are reported. They have Raman scattering in the low‐frequency (LF) region with sharp peaks, one of the prerequisites to design Raman thermometers. The Raman thermometric behaviors are characterized by three vibrational bands, and their thermal sensitivity is compared with their emission thermometric ability. The LF phonon linked with the Au···Au vibration helps increase the thermometric sensitivity of emission and Raman thermometers. Additionally, magnetically diluted complexes containing both Dy3+ and Y3+ ions are prepared to demonstrate the effect of temperature sensing capability through Raman and emission spectroscopy among isostructural mixed‐metal materials. Compounds are immersed inside various benchtop solvents to unravel the robustness and functioning of Raman thermometers. Furthermore, they reveal single‐molecule magnet properties, which disclose the effect of LF phonons on the spin relaxation process. Therefore, the reported molecular materials are Raman and luminescent thermometers, and they contain a molecular magnetic center with thiocyanidoaurate ions playing a critical role due to their emissive and Raman activities.

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

“…In the crystal packing, each Ag( i ) or Au( i ) atom sees three other Ag( i ) or Au( i ) atoms, which are separated by minimum fixed distances of 3.356 Å (NdAg), 3.284 Å (NdAu), 3.324 Å (SmAg), and 3.276 Å (SmAu) at 90 K. The interlayer Ag–Ag or Au–Au distances are comparable with the other isostructural frameworks with different Ln III ions. 55,56 The 3D-network is stabilized with argentophilic or aurophilic interactions as well as hydrogen-bonding interactions between the hydrogen of water and the nitrogen of cyanide from the neighbouring layers along the a - and b -axes.…”

“…Such emissive variations are also visible for other Au(I)/Ag(I) compounds containing different Ln ions. [52][53][54][55][56] Next, SmAu's thermometric ability was characterized because it will be the first Sm(III) possessing a ratiometric thermometer due to the observed abrupt increase in the luminescence intensity (Fig. 5).…”

Multifunctionality of luminescent molecular nanomagnets based on lanthanide complexes

“…Recently, the further expansion of the concept of optical thermometry using emissive Ln-SMMs was presented. 253 For the first time, a combination of the thermometric effects using Raman spectroscopy and photoluminescence was reported. This was shown for novel supramolecular assemblies of {…”

Multifunctional lanthanide-based single-molecule magnets exhibiting luminescence thermometry and photochromic and ferroelectric properties

“…For example, the first homonuclear Dy4 SMM that can also act as a luminescent thermometer is a rare example of dysprosium SMM that accesses the thermometric characteristics involving the ligand triplet emission and Dy III intra 4f transitions. 55 In the same year, a series of novel complexes containing weakly bonded lanthanides and Au I metal were reported 56 and magnetically diluted complexes which involved both Dy III and Y III ions were prepared to reveal SMM properties and the effect of low-frequency phonons on the spin relaxation process. They also demonstrated the effect of the temperature sensing capability through Raman and emission spectroscopy among isomorphous mixed-metal materials.…”