Lanthanide-Grafted Bipyridine Periodic Mesoporous Organosilicas (BPy-PMOs) for Physiological Range and Wide Temperature Range Luminescence Thermometry

Abstract

Bipyridine is the most widely used chelating ligand for developing metal complexes in coordination and supramolecular chemistry. Here, we present a series of three bipyridine periodic mesoporous organosilicas (BPy-PMOs) grafted with lanthanide β-diketonate complex for the purpose of obtaining thermochromic materials, which can be employed as ratiometric temperature sensors. Such thermometers are based on the ratio of two emission intensity peaks and are not affected by factors such as alignment or optoelectronic drift of the excitation source and detectors. Three thermometric systems are studied: Dy−Dy, Tb− Sm, and Tb−Eu with the first two showing very attractive performance. For the first two systems, some of the best reported to date relative sensitivities are observed. In the BPy-PMO@ Dy(acac) 3 system, it is very unusual that the 4 I 15/2 → 6 H 15/2 transition is already occupied at low temperature such as 200 K, which influences its thermometric behavior. The Tb−Sm shows excellent performance in the physiological range and when suspended in water. We have additionally confirmed that the BPy-PMO hybrid materials lack toxicity to human cells, proving them very promising candidates for biomedical thermometric applications.

Luminescent PMMA Films and PMMA@SiO2 Nanoparticles with Embedded Ln3+ Complexes for Highly Sensitive Optical Thermometers in the Physiological Temperature Range**

“…They are much more sensitive, even up to seven times. Although the results for samples based on the Tb 3+ – Sm 3+ system show that their relative sensitivity is slightly higher than those of similar systems with only one material, [36] it has nevertheless shown higher sensitivity. A comparison of our samples with different systems, such as hybrid systems or organic dyes, shows similar or higher sensitivity, even up to four times.…”

“…[30] While the Tb 3+ -Eu 3+ system is an already popular thermometer in the physiological temperature range, [5,13,[31][32][33][34] the Tb 3+ -Sm 3+ system is rarely investigated despite its promising potential, due to the difficulty to obtaining intense Sm 3+ emission at temperatures above room temperature. [35,36] Finally, to explore the potentiality of these materials to be used as thermometers in biological applications, SiO2 nanoparticles coated with doped PMMA films were investigated.…”

“…In particular, doping was carried out with two systems consisting of Tb 3+ – Eu 3+ and Tb 3+ – Sm 3+ mixed‐metal complexes, which were already proved to show promising temperature‐sensing properties in the physiological range [30] . Although the Tb 3+ – Eu 3+ system is an already popular thermometer in the physiological temperature range, [5, 13, 31–34] the Tb 3+ – Sm 3+ system is rarely investigated, despite its promising potential, due to the difficulty in obtaining an intense Sm 3+ emission at temperatures above room temperature [35, 36] . Finally, to explore the potential of these materials to be used as thermometers in biological applications, SiO 2 NPs coated with doped PMMA films were investigated.…”

N‐Rich Porous Polymer with Isolated Tb3+‐Ions Displays Unique Temperature Dependent Behavior through the Absence of Thermal Quenching

“…Bipyridine units are well known in thermometry-based literature as excellent ligands for anchoringo fE u 3 + and Tb 3 + complexes. [16,29] The oxidation states of the grafted Tb and Eu complexes were determined via XPS. In the 3d spectrumo ft he Eu_acac@bpyDAT POP sample ( Figure S8), the observed peaks at 1164.67 eV and 1134.97 eV are characteristic of Eu III 3d 3/2 and Eu III 3d 5/2 binding energies, confirming the 3 + oxidation state of Eu cations.F urthermore, the peaks at 1154.87 eV and 1125.27 eV indicate the binding energies Eu II 3d 3/2 and Eu II 3d 5/2 of the Eu 2 + ions.…”

Highly Ordered Hybrid Mesoporous Organosilica: An Exceptional Anchor for Pd Nanoparticles and Catalyst Nitroaromatic Reduction

“…Mesoporous silicas modi ed/constructed by organosiloxanes (MO) [1][2][3][4] are a class of hybrid silica-based materials that are widely used in the diverse applications including catalysis 4,5 , microextraction 6 , water treatment 7 , molecular recognition 8 , photocatalysis 9 , optical thermometry 10 , sensors 11,12 , CO 2 capture 13,14 . These materials can be synthesized by incorporating organosiloxane bridges and usually have amorphous structure but with ordered/disordered pore channels.…”