Enhanced Near-IR Luminescence and Thermal-Resistant Properties of Yb(III) Complexes Under Solvent-Free Mechanochemical Conditions

Abstract

Mechanochemical activation is of particular significance in the field of sustainable chemistry. This technique can transform mechanical energy into a chemical reaction under solvent-free conditions, while it has rarely been used in the preparation of near-infrared (NIR) luminescent materials. Here, an NIR luminescent complex with a homogeneous shuttlelike morphology was designed and synthesized through a facile mechanochemical process at room temperature. The successful coordination of Yb 3+ with symmetrical terpyridine units and 2thenoyltrifluoroacetonate synergistically allows the obtained Yb 3+ ternary complex to reveal remarkable improvement in the NIR luminescent behavior and thermalresistant performance compared with the mononuclear complex, Yb(tta) 3 •3H 2 O. This enhancement mainly benefits from the removal of water molecules in the first coordination sphere of Yb 3+ through the introduction of terpyridines, thus preventing the diffusion of water molecules to Yb 3+ complexes, and driving the formation of the Yb 3+ complex with more effective coordination number and enhanced the NIR luminescence. This provided a promising environmentally friendly strategy to synthesize highly NIR luminescence materials for eliminating the influence of harmful organic solvents.

Mechanochemical Syntheses of Ln(hfac)3(H2O)x (Ln = La-Sm, Tb): Isolation of 10-, 9-, and 8-Coordinate Ln(hfac)n Complexes

“…Mechanochemical synthesis has the advantage of reducing the use of solvent and potentially reducing losses of soluble starting materials and products. Mechanochemistry has been used to synthesize various lanthanide complexes including some containing β-diketonates − as well as Ln-based metal–organic frameworks . Mechanochemical reactions can include small amounts of solvent, and the reaction can be described as either “liquid-assisted” or a “slurry” depending on the amount of solvent used relative to the mass of solid reagents. , Reactions where a reagent is a liquid are still considered “neat” reactions and may not be considered “liquid-assisted” .…”

Cu2+-Induced “Off–On–Off” Switching Luminescence of Cellulose-Based Luminescent Hydrogels

“…Among numerous luminescent molecules, lanthanide­(III) complexes (LnCs) have gained widespread attention as potential emission centers, due to their unique photoluminescence (PL) properties such as tunable emission lines, high color purity, long excited state time, and large Stokes shift. − Unfortunately, their inherent drawbacks, such as poor photostability, poor mechanical properties, and poor film-forming properties, limit their continuing development in practical applications. Recent studies have highlighted that a combination of LnCs with host matrices (microporous materials, clay, and ILs) is an acceptable method to circumvent the above shortcomings. − The pores of regenerated cellulose gels can be filled with LnCs to develop novel organic–inorganic composites, in which the excellent optical properties of LnCs were effectively combined with the natural advantages of cellulose, promoting their wider application in luminescent sensors and flexible optical switches. − Recently, we have been highly interested in the embedding of LnCs in the chitosan biopolymers under carboxyl-functionalized ionic liquids to synthesize flexible luminescent films, which can serve as a vapor luminescent sensor .…”

Tough, Self-Healing, and UV Light-Switchable Luminescent Hydrogels with Reversible Stimuli-Responsive Properties for Cu2+

“…into LHs represents an appealing approach to integrate the above multiple properties simultaneously. − Particularly, LHs constructed via hydrogen bonds are effective and attractive candidates to improve the weaknesses of brittleness and deficiency of stimuli-responsive behavior achieved from covalent hydrogels . In terms of emitting centers, one typical luminescent material is LnCs with narrow and abundant emission bands, large Stokes shifts, and high color purity, enabling LnCs’ tunable emission color, PL intensity, and lifetime, which is of great significance for outputting “On–Off” switchable response information in real time. − The other important and promising materials are luminescent quantum dots (QDs). Among these, sulfur QDs (S-QDs) are more attractive owing to their excellent water dispersibility, low cytotoxicity, and unique PL features. − Under different UV excitation wavelengths, LnCs containing Eu 3+ and Tb 3+ exhibit red or green emission while S-QDs display blue emission.…”