Ratiometric Luminescent Thermometer Based on the Lanthanide Metal–Organic Frameworks by Thermal Curing
Huiru Guan, Mixiang Qi, Lifeng Shi, Weisheng Liu, Lizi Yang, Wei Dou
Abstract
The high-performance optical thermometer probes are of great significance in diverse areas; lanthanide metal–organic frameworks (Ln-MOFs) are a promising candidate for luminescence temperature sensing owing to their unique luminescence properties. However, Ln-MOFs have poor maneuverability and stability in complex environments due to the crystallization properties, which then hinder their application scope. In this work, the [email protected] composite was successfully prepared using simple covalent crosslinking through uncoordinated −NH 2 or COOH on Tb-MOFs reacting with the epoxy groups on TGIC {Tb-MOFs = [Tb 2 (atpt) 3 (phen) 2 (H 2 O)] n; H 2 atpt = 2-aminoterephthalic acid; phen = 1,10-phenanthroline monohydrate}. After curing, the fluorescence properties, quantum yield, lifetime, and thermal stability of [email protected] were remarkably enhanced. Meanwhile, the obtained [email protected] composites exhibit excellent temperature sensing properties in the low-temperature ( S r = 6.17% K –1 at 237 K), physiological temperature ( S r = 4.86% K –1 at 323 K), or high-temperature range ( S r = 3.88% K –1 at 393 K) with high sensitivity. In the temperature sensing process, the sensing mode of single emission changed into double emission for ratiometric thermometry owing to the back energy transfer (BenT) from Tb-MOFs to TGIC linkers, and the BenT process enhanced with the increase of temperature, which further improved the accuracy and sensitivity of temperature sensing. Most notably, the temperature-sensing [email protected] can be easily coated on the surface of polyimide (PI), glass plate, silicon pellet (SI), and poly(tetrafluoroethylene) plate (PTFE) substrates by a simple spraying method, which also exhibited an excellent sensing property, making it applicable for a wider T range measurement. This is the first example of a postsynthetic Ln-MOF hybrid thermometer operative over a wide temperature range including the physiological and high temperature based on back energy transfer.