Preparation and properties of temperature sensitive paint based on Eu(DBM)3phen as probe molecule

UV-barrier poly(lactic acid) film with light-stabilized Eu complexes as filler

The poor UV shielding property of PLA limit it further applications on food packaging. The rare-earth complex Eu(DBM)3phen converts absorbed ultraviolet (UV) light to red light, which inspires the development of new UV shielding materials. However, this complex has low photostability and decomposes easily under UV irradiation. Thus, we prepared a long-lasting rare-earth complex transluminant Eu(DBM)2(BP-2)phen by introducing BP-2 into Eu(DBM)3phen, and blended it with PLA to obtain PLA/Eu(DBM)2(BP-2)phen composite films. The test results showed that the complex could reduce the UV transmittance of PLA films by emitting luminescence and heat. The UV transmittance of the composite film with 0.5 % mass fraction decreased from 87.4 % to 7.7 %, compared to pure PLA films, and remained at 11.6 % after 12 days of UV aging. The film had long-lasting UV shielding performance, good transparency and mechanical properties. Finally, In the storage experiments of flaxseed oil, the P/E25 film effectively retarded the oxidation process of the oil.

Fluorescence turn-on mode of Eu3+ complex nanocomposite to detect histamine for seafood freshness

Biogenic amines (BAs), which naturally occur as chemicals in seafood, are indicators of food freshness and quality. High concentrations of BAs can cause an undesirable inflammatory response. However, traditional detection methods cannot meet the needs of rapid analysis nowadays. It is essential to explore a simple and valid method to monitor the food quality. Herein, we design and prepare a nanoclay-based turn on fluorescent material with BAs response, which could be used for the real-time and visual detection of raw fish freshness. As the concentration of BAs increase, the sensor of the fluorescence signal is significantly enhanced. The sensor demonstrated wonderful response and sensitivity which showed a detection limit of 0.935 mg/L for typical BAs histamine within a linear range of 2-14 mg/L in an aqueous solution. More importantly, we developed a responsive BAs device by doping the sensor into polyvinyl alcohol (PVA), which is well applied as a rapid-responsive fluorescent marker for visual monitoring the freshness of raw fish.

Overview of N-Rich Antennae Investigated in Lanthanide-Based Temperature Sensing

The market share of noncontact temperature sensors is expending due to fast technological and medical evolutions. In the wide variety of noncontact sensors, lanthanide-based temperature sensors stand out. They benefit from high photostability, relatively long decay times and high quantum yields. To circumvent their low molar light absorption, the incorporation of a light-harvesting antenna is required. This Review provides an overview of the nitrogen-rich antennae in lanthanide-based temperature sensors, emitting in the visible light spectrum, and discusses their temperature sensor ability. The N-rich ligands are incorporated in many different platforms. The investigation of different antennae is required to develop temperature sensors with diverse optical properties and to create a diverse offer for the multiple application fields. Molecular probes, consisting of small molecules, are first discussed. Furthermore, the thermometer properties of ratiometric temperature sensors, based on di- and polynuclear complexes, metal-organic frameworks, periodic mesoporous organosilicas and porous organic polymers, are summarized. The antenna mainly determines the application potential of the ratiometric thermometer. It can be observed that molecular probes are operational in the broad physiological range, metal-organic frameworks are generally very useful in the cryogenic region, periodic mesoporous organosilica show temperature dependency in the physiological range, and porous organic polymers are operative in the cryogenic-to-medium temperature range.

Exploring polylactide/poly(butylene adipate-co-terephthalate)/rare earth complexes biodegradable light conversion agricultural films

In this work, rare earth europium was combined with different organic ligands to obtain two kinds of rare earth conversion agents, Eu(DBM)₄CPC and Eu(TTA)₃(TPPO)₂. Two kinds of conversion films were successfully prepared by combining them with polylactide and poly(butylene adipate-co-terephthalate). Results showed that the film has excellent light conversion ability and high color purity, and rare earth complexes improved melt flowing property and decreased melt viscosity of blend. At the same time, the elongation at break of the film increased greatly, which could up to 595.0/460.9% in the both machine direction (MD) and transverse direction (TD). The results of GPC show that rare earth complexes can make main chain of PLA scission, which causes rapid molecular weight reduction, and the effect of Eu(DBM)₄CPC on the molecular weight of PLA was more significant than Eu(TTA)₃(TPPO)₂. SEM shows that the complicity of PLA and PBAT has been improved, the dispersed phase of the blend is more uniform. DSC shows that both rare earth complexes can improve the crystallization capacity of PLA. And with the addition of cetylpyridinium chloride could improve the compatibility of rare earth complexes and polymer materials, the light transmittance and hydrophilicity of the film also increased obviously.

EDTA-bonded multi-connected carbon-dots and their Eu3+ complex: preparation and optical properties

EDTA-bonded multi-connected carbon-dots (EDTA–C-dots) were prepared from carbon dot precursors and complexed with Eu³⁺ to give Eu³⁺-coordinated EDTA-bonded multi-connected carbon dots (Eu–EDTA–C-dots). Whereas EDTA–C-dots were readily soluble in DMSO, Eu–EDTA–C-dots could not be easily dissolved in DMSO, water, or other common organic solvents. The newly prepared materials were thoroughly characterized. The X-ray diffraction results showed that no crystalline phase of Eu oxides (europium oxide or europium hydroxide) could be observed in Eu–EDTA–C-dots. The infrared and UV-Vis spectra showed that coordination with Eu³⁺ ions did not damage the structure of the EDTA–C-dots. It was found that EDTA could be easily grafted on the surface of carbon dots and EDTA had minimal influence on the photoluminescence of the carbon dot matrix. In contrast, the existence of Eu³⁺ ions strongly quenched the photoluminescence of Eu–EDTA–C-dots. The measured and fitted decay lifetime indicated that Eu–EDTA–C-dots possessed two photoluminescence decay processes, i.e., radiative recombination and non-radiative recombination.

EDTA-bonded multi-connected carbon-dots (EDTA–C-dots) were prepared from carbon dot precursors and complexed with Eu³⁺ to give Eu³⁺-coordinated EDTA-bonded multi-connected carbon dots (Eu–EDTA–C-dots).