Speciation, Luminescence, and Alkaline Fluorescence Quenching of 4-(2-methylbutyl)aminodipicolinic acid (H2MEBADPA)

4-(2-Methylbutyl)aminodipicolinic acid (H2MEBADPA) has been synthesized and fully characterized in terms of aqueous phase protonation constants (pKa\u27s) and photophysical measurements. The pKa\u27s were determined by spectrophotometric titrations, utilizing a fully sealed titration system. Photophysical measurements consisted of room temperature fluorescence and frozen solution phosphorescence as well as quantum yield determinations at various pH, which showed that only fully deprotonated MEBADPA2– is appreciably emissive. The fluorescence of MEBADPA2– has been determined to be quenched by hydroxide and methoxide anions, most likely through base-catalyzed excited-state tautomerism or proton transfer. This quenching phenomenon has been quantitatively explored through steady-state and time-resolved fluorescence measurements. Utilizing the determined pKas and quenching constants, the fluorescent intensity of MEBADPA2– has been successfully modeled as a function of pH

Brilliant Photoluminescence and Triboluminescence from Ternary Complexes of Dy^III and Tb^III with 3‑Phenyl-4-propanoyl-5-isoxazolonate and a Bidentate Phosphine Oxide Coligand

Three new lanthanide heterocyclic β-diketonate complexes [Dy­(PPI)₃(EtOH)₂] (<b>1</b>), [Dy­(PPI)₃(DPEPO)] (<b>2</b>), and [Tb­(PPI)₃(DPEPO)] (<b>3</b>) [where HPPI = 3-phenyl-4-propanoyl-5-isoxazolone and DPEPO = bis­(2-(diphenylphosphino)­phenyl)­ether oxide] have been synthesized and fully characterized. Single-crystal X-ray diffraction analyses reveal that these complexes are mononuclear and that the central Ln^III ion is coordinated to eight oxygen atoms that are provided by three bidentate β-diketonate ligands and ethanol or bidentate DPEPO in a distorted square antiprismatic geometry. These complexes have high molar absorption coefficients (up to 3 × 10⁴ M^–1 cm^–1 at 285 nm) and display strong visible and, for Dy^III, NIR luminescence upon irradiation at the ligand-centered band in the range 250–350 nm. The emission quantum yields and the luminescence lifetimes at room temperature are 3 ± 0.5% and 15 ± 1 μs for <b>1</b>, 12 ± 2% and 33 ± 1 μs for <b>2</b>, and 42 ± 6% and 795 ± 1 μs for <b>3</b>. Moreover, the crystals of <b>2</b> and <b>3</b> exhibit brilliant triboluminescence, visible in daylight

Brilliant Photoluminescence and Triboluminescence from Ternary Complexes of Dy^III and Tb^III with 3‑Phenyl-4-propanoyl-5-isoxazolonate and a Bidentate Phosphine Oxide Coligand

Three new lanthanide heterocyclic β-diketonate complexes [Dy­(PPI)₃(EtOH)₂] (<b>1</b>), [Dy­(PPI)₃(DPEPO)] (<b>2</b>), and [Tb­(PPI)₃(DPEPO)] (<b>3</b>) [where HPPI = 3-phenyl-4-propanoyl-5-isoxazolone and DPEPO = bis­(2-(diphenylphosphino)­phenyl)­ether oxide] have been synthesized and fully characterized. Single-crystal X-ray diffraction analyses reveal that these complexes are mononuclear and that the central Ln^III ion is coordinated to eight oxygen atoms that are provided by three bidentate β-diketonate ligands and ethanol or bidentate DPEPO in a distorted square antiprismatic geometry. These complexes have high molar absorption coefficients (up to 3 × 10⁴ M^–1 cm^–1 at 285 nm) and display strong visible and, for Dy^III, NIR luminescence upon irradiation at the ligand-centered band in the range 250–350 nm. The emission quantum yields and the luminescence lifetimes at room temperature are 3 ± 0.5% and 15 ± 1 μs for <b>1</b>, 12 ± 2% and 33 ± 1 μs for <b>2</b>, and 42 ± 6% and 795 ± 1 μs for <b>3</b>. Moreover, the crystals of <b>2</b> and <b>3</b> exhibit brilliant triboluminescence, visible in daylight

Lanthanide Sensitization in II−VI Semiconductor Materials: A Case Study with Terbium(III) and Europium(III) in Zinc Sulfide Nanoparticles

International audienceThis work explores the sensitization of luminescent lanthanide Tb3+ and Eu3+ cations by electronic structure of zinc sulfide (ZnS) semiconductor nanoparticles. Excitation spectra collected while monitoring the lanthanide emission bands reveal that the ZnS nanoparticles act as an antenna for the sensitization of Tb3+ and Eu3+. The mechanism of lanthanide ion luminescence sensitization is rationalized in terms of an energy and charge transfer between trap sites and is based on a semiempirical model, proposed by Dorenbos and co-workers (Dorenbos, P. J. Phys.: Condens Matter 2003, 15, 8417-8434; J. Lumin. 2004, 108, 301-305; J. Lumin. 2005, 111, 89-104. Dorenbos, P.; van der Kolk, E. Appl. Phys. Lett. 2006, 89, 061122-1-061122-3; Opt. Mater. 2008, 30, 1052-1057. Dorenbos, P. J. Alloys Compd. 2009, 488, 568-573; references 1-6.) to describe the energy level scheme. This model implies that the mechanisms of luminescence sensitization of Tb3+ and Eu3+ in ZnS nanoparticles are different; namely, Tb3+ acts as a hole trap, whereas Eu3+ acts as an electron trap. Further testing of this model is made by extending the studies from ZnS nanoparticles to other II-VI semiconductor materials; namely, CdSe, CdS, and ZnSe