Luminescent Properties of Lanthanoid-Poly(Sodium Acrylate) Composites: Insights on the Interaction Mechanism

Luminescent Papers with Asymmetric Complexes of Eu(III) and Tb(III) in Polymeric Matrices and Suggested Combinations for Color Tuning

Complexes of lanthanide ions, such as Eu(III) (red light emission) and Tb(III) (green light emission), with proper ligands can be highly luminescent and color-tunable, also attaining yellow and orange emission under UV radiation. The ligands employed in this work were poly(sodium acrylate), working as polymeric matrix, and 1,10-phenanthroline, taking advantage of its antenna effect. Possibilities of color display were further enhanced by incorporating a cationic polyfluorene with blue emission. This strategy allowed for obtaining cyan and magenta, besides the aforementioned colors. Uncoated cellulose paper was impregnated with the resulting luminescent inks, observing a strong hypsochromic shift in excitation wavelength upon drying. Hence, while a cheap UV-A lamp sufficed to reveal the polyfluorene's blue emission, shorter wavelengths were necessary to visualize the emission due to lanthanide ions as well. The capacity to reveal, with UV-C radiation, a full-color image that remains invisible under natural light is undoubtedly useful for anti-counterfeiting applications. Furthermore, both lanthanide ion complexes and polyfluorenes were shown to have their luminescence quenched by Cu(II) ions and nitroarenes, respectively.

A red-emitting Europium(III) complex as a luminescent probe with large Stokes shift for the sequential determination of Cu2+ and biothiols in real samples

In this work, a novel Eu³⁺-DTPA-bis(AMC) complex with red luminescence was designed and synthesized for sequential detection of Cu²⁺ and biothiols (Cys/Hcy/GSH) based on the displacement strategy with the good selectivity, high sensitivity, and large Stokes shift (288 nm). The possible detection mechanism was verified by UV-vis, the high-resolution mass spectrometry, and the fluorescence decay curve. The experimental parameters, including the solution pH, the incubation time, the concentration ratio of Eu³⁺-DTPA-bis(AMC) to Cu²⁺ and biothiols concentration, were optimized. Under the optimal conditions, it shows a good linear relationship between the concentration (0-10 μM) of Cu²⁺ and the fluorescence intensity of Eu³⁺-DTPA-bis(AMC), with a low detection limit of 0.065 μM. The linear range and the limit of detection of the Eu³⁺-DTPA-bis(AMC)/Cu²⁺ system for Cys/Hcy/GSH were 2.5-22.5/5-45/5-50 μM and 0.11/0.07/0.05 μM, respectively. Surprisingly, the high or low concentration of Eu³⁺-DTPA-bis(AMC)/Cu²⁺ can significantly affect the selectivity of the sensing system to biothiols (Cys/GSH/Hcy). When the concentration of the Eu³⁺-DTPA-bis(AMC)/Cu²⁺ system is 10.0 μΜ, it could recognize biothiols (Cys/GSH/Hcy) from other substances, but when the concentration is as low as 3.3 μM, it could further specifically distinguished Cys from Hcy/GSH. Owing to the high anti-interference characteristics, accuracy and specificity, the sensing system was well applied to the cascade detection of Cu²⁺ in actual environmental samples and Cys in biological and food samples, including FBS, urine, milk, beverage, fresh juice with the satisfactory recoveries from 96.20 to 106.80 %.

Reusable and pH-Stable Luminescent Sensors for Highly Selective Detection of Phosphate

Phosphate sensors have been actively studied owing to their importance in water environment monitoring because phosphate is one of the nutrients that result in algal blooms. As with other nutrients, seamless monitoring of phosphate is important for understanding and evaluating eutrophication. However, field-deployable phosphate sensors have not been well developed yet due to the chemical characteristics of phosphate. In this paper, we report on a luminescent coordination polymer particle (CPP) that can respond selectively and sensitively to a phosphate ion against other ions in an aquatic ecosystem. The CPPs with an average size of 88.1 ± 12.2 nm are embedded into membranes for reusable purpose. Due to the specific binding of phosphates to europium ions, the luminescence quenching behavior of CPPs embedded into membranes shows a linear relationship with phosphate concentrations (3-500 μM) and detection limit of 1.52 μM. Consistent luminescence signals were also observed during repeated measurements in the pH range of 3-10. Moreover, the practical application was confirmed by sensing phosphate in actual environmental samples such as tap water and lake water.

Ligands as copper and nickel ionophores: Applications and implications on wastewater treatment

Modern society depends on many finite natural resources, from which metals are of great importance. Copper and nickel's relevance is due to their vast applications, resulting in high market value and demand. As such, their polluting emissions are also significant and their removal from wastewaters is imperative. Moreover, effluent treatment techniques can be used to recover the metallic cations, via selective processes. In this review, copper and nickel selective ligands in the literature are surveyed. These are most commonly Schiff bases, along with crown ethers and porphyrins. They are usually employed in ion sensing (colorimetric chemosensors or electrodes) with great success - the disruption in response of colorimetric sensors is up to 7% and binding constants are usually at least one order of magnitude greater with the desired cation than with interferents. However, modified adsorbents are also reported. The possibilities of using ionophores in wastewater cleaning, allowing the treatment of effluents and the selective recovery of valuable materials, and their implications on new green policies is discussed.