112776-84-8Relevant articles and documents
Efficient formation of luminescent lanthanide(III) complexes by solid-phase synthesis and on-resin screening
Nakamura, Tatsuya,Mizukami, Shin,Tanaka, Miho,Kikuchi, Kazuya
, p. 2685 - 2690 (2013)
Time-resolved luminescence measurements of luminescent lanthanide complexes have advantages in biological assays and high-throughput screening, owing to their high sensitivity. In spite of the recent advances in their energy-transfer mechanism and molecular-orbital-based computational molecular design, it is still difficult to estimate the quantum yields of new luminescent lanthanide complexes. Herein, solid-phase libraries of luminescent lanthanide complexes were prepared through amide-condensation and Pd-catalyzed coupling reactions and their luminescent properties were screened with a microplate reader. Good correlation was observed between the time-resolved luminescence intensities of the solid-phase libraries and those of the corresponding complexes that were synthesized by using liquid-phase chemistry. This method enabled the rapid and efficient development of new sensitizers for SmIII, EuIII, and TbIII luminescence. Thus, solid-phase combinatorial synthesis combined with on-resin screening led to the discovery of a wide variety of luminescent sensitizers. La confidential: Solid-phase synthesis by using amide-condensation and Pd-coupling reactions enabled the efficient development of new antenna ligands for SmIII, EuIII, and Tb III atoms for discovering a wide variety of luminescent sensitizers. Copyright
Electron transfer pathways in photoexcited lanthanide(iii) complexes of picolinate ligands
Kovacs, Daniel,Kocsi, Daniel,Wells, Jordann A. L.,Kiraev, Salauat R.,Borbas, K. Eszter
supporting information, p. 4244 - 4254 (2021/04/06)
A series of luminescent lanthanide(iii) complexes consisting of 1,4,7-triazacyclononane frameworks and three secondary amide-linked carbostyril antennae were synthesised. The metal binding sites were augmented with two pyridylcarboxylate donors yielding octadentate ligands. The antennae carried methyl, methoxymethyl or trifluoromethyl substituents in their 4-positions, allowing for a range of excited state energies and antenna electronic properties. The1H NMR spectra of the Eu(iii) complexes were found to be analogous to each other. Similar results were obtained in the solid-state by single-crystal X-ray crystallography, which showed the structures to have nine-coordinate metal ions with heavily distorted tricapped trigonal prismatic geometries. Steady-state and time-resolved luminescence spectroscopy showed that the antennae could sensitize both Tb(iii) and Eu(iii), however, quantum yields were lower than in other octadentate complexes lacking pyridylcarboxylate. Complexes with more electron-poor pyridines were less emissive even when equipped with the same antenna. The oxidation and reduction potentials of the antennae and the pyridinecarboxylates, respectively, were determined by cyclic voltammetry. The obtained values were consistent with electron transfer from the excited antenna to the pyridine providing a previously unexplored quenching pathway that could efficiently compete with energy transfer to the lanthanide. These results show the crucial impact that photophysically innocent ligand binding sites can have on lanthanide luminescence.
Synthesis of 12-Membered Tetra-aza Macrocyclic Pyridinophanes Bearing Electron-Withdrawing Groups
Yepremyan, Akop,Mekhail, Magy A.,Niebuhr, Brian P.,Pota, Kristof,Sadagopan, Nishanth,Schwartz, Timothy M.,Green, Kayla N.
, p. 4988 - 4998 (2020/04/02)
The number of substituted pyridine pyridinophanes found in the literature is limited due to challenges associated with 12-membered macrocycle and modified pyridine synthesis. Most notably, the electrophilic character at the 4-position of pyridine in pyridinophanes presents a unique challenge for introducing electrophilic chemical groups. Likewise, of the few reported, most substituted pyridine pyridinophanes in the literature are limited to electron-donating functionalities. Herein, new synthetic strategies for four new macrocycles bearing the electron-withdrawing groups CN, Cl, NO2, and CF3 are introduced. Potentiometric titrations were used to determine the protonation constants of the new pyridinophanes. Further, the influence of such modifications on the chemical behavior is predicted by comparing the potentiometric results to previously reported systems. X-ray diffraction analysis of the 4-Cl substituted species and its Cu(II) complex are also described to demonstrate the metal binding nature of these ligands. DFT analysis is used to support the experimental findings through energy calculations and ESP maps. These new molecules serve as a foundation to access a range of new pyridinophane small molecules and applications in future work.
