Highly luminescent bis-diketone lanthanide complexes with triple-stranded dinuclear structure

Abstract

A new bis-β-diketone, 3,3'-bis(4,4,4-trifluoro-1,3-dioxobutyl)biphenyl (BTB), has been designed and prepared for the synthesis of a series of dinuclear lanthanide complexes [Ln(2)(BTB)(3)(C(2)H(5)OH)(2)(H(2)O)(2)] [Ln = Eu (1), Gd (2)], [Ln(2)(BTB)(3)(DME)(2)] [Ln = Nd (3), Yb (4); DME = ethylene glycol dimethyl ether] and [Eu(2)(BTB)(3)(L)(2)] [L = 2,2-bipydine (5); 1,10-phenanthroline (6); 4,7-diphenyl-1,10-phenanthroline (7)]. Complexes 1-7 have been characterized by various spectroscopic techniques and their photophysical properties are investigated. X-ray crystallographical analysis reveals that complexes 1, 3 and 4 adopt triple-stranded dinuclear structures which are formed by three bis-bidentate ligands with two lanthanide ions. The complexes 1 and 3-7 display strong visible red or NIR luminescence upon irradiation at ligand band around 372 nm, depending on the choice of the lanthanide. The solid-state photoluminescence quantum yields and the lifetimes of Eu(3+) complexes are determined and described.

Synthesis, Crystal Structure, and Near‐IR Luminescent Properties of Lanthanide Bis(β‐diketonate) Complexes

“…Excitation spectra of complexes 1-3 at 298 K are shown in Figures S17 of the Supporting Information. [22] Decay curves of these complexes could be fitted bi-exponentially when monitored at about 975 nm in the powder form with a domain lifetime of the order of μs, as shown in Table 2. Decay curves of these complexes could be fitted bi-exponentially when monitored at a wavelength of ca.…”

Two Series of Substituent‐Group‐Directed Adipate‐Based Lanthanide Coordination Polymers: Syntheses, Structures, Photoluminescence, and Magnetism

“…The decay curve was fitted by a mono‐exponential function, providing a lifetime value of τ = 1502 µs. The relatively longer lifetimes for 9 and 11 than 3 and 5 may be due to the nonradiative quenching of the Ln III radiation caused by the coordinated water molecules in 3 and 5 . Because there are two crystallographically independent Ln III ions without coordinated water molecules in the crystal structures of 9 and 11 (Ln1 and Ln3, Figure S3).…”

Synthesis, photoluminescent features and intramolecular energy transfer mechanism of europium (III) complexes with fluorinate β-diketone ligand and auxiliary ligands

“…The low intensity emission peak at 17,241.38 cm À1 due to 5 D 0 -7 F 0 transition being a one-order perturbation is forbidden in electric as well as magnetic dipole transition in accordance to theory of Judd-Ofelt [23][24][25]. The emission peak of slightly higher intensity at 16,920.47 cm À1 due to 5 D 0 -7 F 1 transition is magnetic dipole transition being independent on local chemical environment can be employed as an internal standard to infer the differences in ligands [25][26][27]. The most intense peak at 16,313.21 cm À1 due to 5 D 0 -7 F 2 transition being electric dipole transition depends on highly polarizable coordination environment around the europium ion possessing very low value of full width at half maxima (FWHM) i.e.…”

“…6.9 nm, 6.5 nm, 5.6 nm, 3.9 nm and 3.6 nm corresponding to the complexes C1-C5, leading to intense pure red emission. The excellent intensity of 5 D 0 -7 F 2 transition as compared to 5 D 0 -7 F 1 transition points to the lack of an inversion symmetry in the coordination environment of europium ion [26][27][28]. The luminescent intensity ratio (I 1 /I 2 = 5 D 0 -7 F 2 / 5 D 0 -7 F 1 ) of electric to magnetic dipole transitions show the symmetry of the coordination sphere as well as monochromaticity properties of metal complexes, their values are found to be in the range 7.0-10.73, being the highest for complex C5.…”