Metal–Organic Framework Optical Thermometer Based on Cr³⁺ Ion Luminescence

Abstract

Metal–organic frameworks with perovskite structures have recently attracted increasing attention due to their structural, optical, and phonon properties. Herein, we report the structural and luminescence studies of a series of six heterometallic perovskite-type metal–organic frameworks with the general formula [EA]2NaCr x Al1–x (HCOO)6, where x = 1, 0.78, 0.57, 0.30, 0.21, and 0. The diffuse reflectance spectral analysis provided valuable information, particularly on crystal field strength (Dq/B) and energy band gap (E g). We showed that the Dq/B varies in the 2.33–2.76 range depending on the composition of the sample. Performed Raman, XRD, and lifetime decay analyses provided information on the relationship between those parameters and the chemical composition. We also performed the temperature-dependent luminescence studies within the 80–400 K range, which was the first attempt to use an organic–inorganic framework luminescence thermometer based solely on the luminescence of Cr3+ ions. The results showed a strong correlation between the surrounding temperature, composition, and spectroscopic properties, allowing one to design a temperature sensing model. The temperature-dependent luminescence of the Cr3+ ions makes the investigated materials promising candidates for noncontact thermometers.

Taking Advantage of a Luminescent ESIPT-Based Zr-MOF for Fluorochromic Detection of Multiple External Stimuli: Acid and Base Vapors, Mechanical Compression, and Temperature

“…The design and synthesis of luminescent materials able to detect changes in the temperature of the medium is also one important target of the scientific community, ,, since luminescent thermometers can replace conventional ones in a multitude of industrial processes where electrical/magnetic fields, different environmental conditions, and/or high temperatures preclude the use of these types of thermometers. , In addition to that, the possibility of detecting changes of temperature in microenvironments (e.g., cells) is of great importance to unveil biological events. , Hence, herein we have tested the ability of UiO-66-(OH) 2 to detect changes in the temperature in a range between 30 and 160 °C (303–433 K) via luminescent response. To this end, we recorded the emission spectra of UiO-66-(OH) 2 at different temperatures.…”

“…Thermoluminescent Response of UiO-66-(OH) 2 . The design and synthesis of luminescent materials able to detect changes in the temperature of the medium is also one important target of the scientific community, 13,58,59 since luminescent thermometers can replace conventional ones in a multitude of industrial processes where electrical/magnetic fields, different environmental conditions, and/or high temperatures preclude the use of these types of thermometers. 16,60 In addition to that, the possibility of detecting changes of temperature in microenvironments (e.g., cells) is of great importance to unveil biological events.…”

Luminescence Thermometry Beyond the Biological Realm

“…We highlight Cr 3+ as one of the most frequently investigated TM ions. Here, common approaches include ratiometric thermometry based on the relative emission intensities of the bands corresponding to the 2 E to 4 A 2 and 4 T 2 to 4 A 2 transitions or thermometry based on the lifetimes of these excited states. − The same transitions have also been applied for thermometry using Mn 3+ or Mn 4+ , another popular TM ion …”

Tetra-Nuclear Cluster-Based Lanthanide Metal–Organic Frameworks as White Phosphor, Information Encryption, Self-Calibrating Thermometers, and Fe2+ Sensors

“…Considering the synergistic effect of ligands and metal ions, , unique and excellent luminescent properties of high luminous purity, large Stokes displacement, line-like emission peaks, long luminescence lifetime, and so on, , lanthanide metal–organic frameworks (LnMOFs) show promising applications in the areas of white phosphor, anti-counterfeiting, self-calibrating temperature thermometers, sensing, and so on. However, one kind of LnMOF material that shows the application in the above multiple fields of white phosphor, anti-counterfeiting, self-calibrating thermometers, and metal ions sensing is not reported, to the best of our knowledge, , because the design of material used in multiple fields need multi-objective and multiple physical properties optimization. − …”