A work in Advanced Functional Materials shows how MOF nanoparticles prepared with spray-drying and containing lanthanide metals may be used as nanothermometers operative over a wide range of temperatures, including in the cryogenic range.

Members of the ICN2 have collaborated in new research to obtain nanothermometers that can provide accurate, noninvasive and self-referenced temperature measurements at the submicrometer scale. The research has been coordinated from University of Aveiro (Portugal). The results have been published in Advanced Functional Materials in an article titled "Lanthanide–Organic Framework Nanothermometers Prepared by Spray-Drying".

The thermal dependence of the phosphor's luminescence provides high detection sensitivity and spatial resolution with short acquisition times in, for example, biological fluids, strong electromagnetic fields, and fast-moving objects.

The strategy the researchers pursued relies on the thermal dependence of phosphor luminescence, which provides high detection sensitivity and special resolution with short acquisition times in such mediums as biological fluids, strong electromagnetic fields, and fast-moving objects.

The temperature determination is usually based on the change of the luminescence intensity or decay times. However, the measurements based on a single f–f transition may be much affected by the variation of the sensor concentration and the drift of the optoelectronic systems—namely, the excitation sources and detectors. Recently, authors reported self-reference nanothermometers based on the intensity ratio of two f–f transitions that overcome the drawbacks of temperature determination with a single transition.

The article also shows that spray-drying prepared MOF nanoparticles may be used as ratiometric luminescent nanothermometers operative over a wide range of temperatures—in particular, the cryogenic range. Prof Maspoch and Dr Imaz have contributed in the synthesis of the MOF nanoparticles of Tb(III) and Eu(III), the first lanthanide-organic framework prepared by the spray-drying method. This system is the most sensitive cryogenic nanothermometer reported so far, combining high sensitivity, reproducibility, and low-temperature uncertainty.

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More information: "Lanthanide–Organic Framework Nanothermometers Prepared by Spray-Drying." Adv. Funct. Mater.. doi: 10.1002/adfm.201500518 Journal information: Advanced Functional Materials "Lanthanide–Organic Framework Nanothermometers Prepared by Spray-Drying.". doi: 10.1002/adfm.201500518