Non-invasive precise thermometers working at the nanoscale with high spatial resolution, where the conventional methods are ineffective, have emerged over the last couple of years as a very active field of research. This has been strongly stimulated by the numerous challenging requests arising from nanotechnology and biomedicine. This critical review offers a general overview of recent examples of luminescent and non-luminescent thermometers working at nanometric scale. Luminescent thermometers encompass organic dyes, QDs and Ln 3+ ions as thermal probes, as well as more complex thermometric systems formed by polymer and organic-inorganic hybrid matrices encapsulating these emitting centres. Non-luminescent thermometers comprise of scanning thermal microscopy, nanolithography thermometry, carbon nanotube thermometry and biomaterials thermometry. Emphasis has been put on ratiometric examples reporting spatial resolution lower than 1 micron, as, for instance, intracellular thermometers based on organic dyes, thermoresponsive polymers, mesoporous silica NPs, QDs, and Ln 3+ -based up-converting NPs and b-diketonate complexes. Finally, we discuss the challenges and opportunities in the development for highly sensitive ratiometric thermometers operating at the physiological temperature range with submicron spatial resolution.

A unique Eu3+/Tb3+ luminescent self‐referencing nanothermometer allowing absolute measurements in the 10–350 K temperature range and sub‐micrometer spatial resolution is reported (see Figure). It has up to 4.9%·K−1 temperature sensitivity and high photostability for long‐term use. The combination of molecular thermometry, superparamagnetism and luminescence in a nanometric host matrix provides multifunctionality opening the way for new exciting applications.

Urea and urethane cross-linked hybrids, classed as di-ureasils and di-urethanesils, were prepared through sol−gel derived carboxylic acid solvolysis. The resulting nanohybrids were characterized by X-ray diffraction, mid-infrared spectroscopy, 29Si and 13C nuclear magnetic resonance, and photoluminescence spectroscopy and results were compared with those of similar hybrid materials obtained from the conventional sol−gel route. The results indicate a similar structure for the hybrids, independent of the synthesis process used. All the hybrids are efficient room-temperature white-light emitters with emission quantum yields between 6 and 20%. The emission quantum yields of hybrids prepared through carboxylic acid solvolysis are 27−35% higher than those calculated for the di-ureasils and di-urethanesils synthesized via the conventional sol−gel technique. This is attributed to the presence of a larger number of nonbonded NH urea- and urethane-groups in the hybrids prepared by carboxylic acid solvolysis, illustrating the key role played by the synthetic method on the extent and magnitude of hydrogen bonding involving urea and urethane linkages.

Non-invasive accuarate thermometers with high spatial resolution and operating at sub-micron scales, where the conventional methods are ineffective, is currently a very active field of research strongly stimulated in the last couple of years by the challenging demands of nanotechnology and biomedicine. This review offers a general overview of recent examples of accurate luminescent 10 thermometers working at micrometric and nanometric scales, particularly those involving advanced Ln 3+ -based functional organic−inorganic hybrid materials. 95 the Ministry of Education. CDSB (SFRH/BD/38472/2007) and PPL (SFRH/BPD/34365/2006) thank FCT for grants. NJOS acknowledges FCT for Ciência 2008 program.

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