Luminescence and energy transfer processes in europium and terbium complexes with 2-substituted cycloalkanones and 1,10-phenanthroline derivatives

Efficient Europium Sensitization via Low-Level Doping in a 2-D Bismuth-Organic Coordination Polymer

A new bismuth-organic compound containing 1,10-phenanthroline (phen) and 2,5-pyridinedicarboxylic acid (PDC) was synthesized and structurally characterized by single-crystal X-ray diffraction. The structure consists of 2-D {Bi(phen)(HPDC)(PDC)}n sheets wherein the PDC ligands bridge metal centers via three unique bonding modes. The 2-D sheets are further connected through strong hydrogen-bonding interactions to form a 3-D supramolecular network. The parent compound displayed yellow photoluminescence in the solid state at room temperature. Doping studies were undertaken to incorporate Eu3+ into the structure, statistically replacing Bi3+ in small quantities (1, 5, and 10 mol % Eu3+ relative to Bi3+). All three compounds displayed characteristic Eu3+ emission, with total quantum yields as high as 16.0% and sensitization efficiencies between 0.21 and 0.37 depending on the Eu3+ doping percentage.

Preparation and Characterization of a Novel Terbium Complex Coordinated with 10-Undecenoic Acid for UV-Cured Coatings

A UV-cured composite containing a rare earth complex was prepared for this study. First, the photoluminescent terbium complex was synthesized with a long-chain unsaturated fatty acid (10-Undecenoic acid) by a solution precipitation method, resulting in the 10-UA-Tb(III) complex. Its structure was proven by FTIR, elemental analysis, XRD, and TGA. The results indicated that the organic acid ligand successfully coordinated with the Tb3+ ion and that the complex had a chelate bidentate structure. The emission spectrum of the 10-UA-Tb(III) complex indicated that the complex can emit a bright green light with the unique luminescence of the Tb3+ ion. Furthermore, the luminescence properties of complexes with different ratios of Tb3+ and ligand were studied, and the ratio of Tb3+ and the ligand had an obvious impact on the luminescence intensity of the 10-UA-Tb(III) complex. Subsequently, the prepared rare earth complex was doped into a UV-cured coating in different proportions to obtain a UV-cured composite. The morphology of the rare earth UV-cured composite was observed by SEM. The images showed that the rare earth complex was dispersed uniformly in the polymer matrix. Moreover, the composites could emit fluorescence. Additionally, it has good thermal stability and compatibility with the resin. Therefore, these composites should have potential applications in UV curable materials, such as luminescence coatings.

Europium(III) complex with powerful antenna ligands: Interligand interaction

The luminescent properties of europium(III) trifluoroacetate [Eu(TFA)3bipy·3Н2О]∙bipy (I), where TFA - trifluoroacetate anion and bipy - 2,2'bipyridyl were investigated. Despite the presence of two efficient antenna ligands in complex (bipy1 in europium coordination sphere and bipy2 in the outer-sphere) the complex displays weak luminescence. By employing density functional theory-based methods, the luminescence, electron structure, interligand interactions and the processes of energy transfer in I were investigated. The nature of the chemical bond in I was studied by the natural bond orbital analysis. The mechanism of luminescence weakening in the complex was ascertained: competitive energy transfer from coordinated bipy1 ligand on to outer-sphere bipy2 molecule results in appreciable weakening of the antenna effect.

A water-stable 3D Eu-MOF based on a metallacyclodimeric secondary building unit for sensitive fluorescent detection of acetone molecules

A Eu-MOF with high water stability constructed using a systematic metallacyclodimeric motif as a potential chemical sensor for acetone is reported.