Hard-and-soft phosphinoxide receptors for f-element binding: structure and photophysical properties of europium(iii) complexes

Abstract

New phosphinoyl-containing tetradentate heterocycles preorganised for metal ion binding were designed and prepared in high yields. The X-ray structures of two allied phosphinoyl-bearing 2,2'-bipyridyl and phenanthroline ligands, as well as closely related structures of 2,6-bis(diphenylphosphinoyl)pyridine and 9-(diphenylphosphinoyl)-1,10-phenanthroline-2-one, are reported. Complexes of nitrates of several lanthanides and trifluoroacetate of Eu(iii) with two phosphinoyl-bearing 2,2'-bipyridyl and phenanthroline ligands were isolated and characterised. The first structures of lanthanide complexes with phosphinoyl-bearing 2,2'-bipyridyl and phenanthroline ligands are reported. The nature of the counter-ion is crucial for the coordination environment of the metal ion. The photophysical properties of the complexes differring in both the nature of the ligand and counter-ion were investigated. The photophysical properties of the complexes are strongly ligand- and counter-ion-dependent. Absorbance and luminescence excitation spectra of complexes showed main peaks in the UV range which correspond to the absorption of light by the ligand and these are ligand-dependent. Luminescence spectra of complexes show typical europium emission in the red region with a high quantum yield, which corresponds to the transitions D → F (J = 0-6). The value of deviation of the components of D → F and D → F transitions from the inversion centre shows a larger dependence on the counter-ion than on the nature of the ligand. The value of the luminescence quantum yield is larger for europium complexes with 2,2'-bipyridyl-based ligands and NO counter-ions than for complexes with phenanthroline-based ligands and NO counter-ions. A low dependence of the luminescence lifetime of Eu complexes on the nature of the ligand has been demonstrated: values in the solid state were in the range 1.1-2.0 ms.

Comparative Investigation into the Complexation and Extraction Properties of Tridentate and Tetradentate Phosphine Oxide‐Functionalized 1,10‐Phenanthroline Ligands toward Lanthanides and Actinides

“…The average bond distances of central metal to the two nitrogen atoms and two oxygen atoms of L 1 are 2.656 and 2.377 Å, respectively. This average bond distance of EuÀ N is almost the same as that of 2.650 Å in PnPPOEu (TFA) 3 H 2 O complex, [22] and slightly longer than those of 2.628 Å and 2.633 Å in complexes of Eu(BLPhen)(NO 3 ) 3 [17] and Eu(C2-POPhen)(NO 3 ) 3 , [10c] respectively. However, this average bond distance of EuÀ O in EuL 1 (NO 3 ) 3 is obviously shorter than that of 2.454 Å in Eu(C2-POPhen)(NO 3 ) 3 and 2.432 Å in Eu-(BLPhen)(NO 3 ) 3 .…”

Intriguing Effects of Halogen Substitution on the Photophysical Properties of 2,9-(Bis)halo-Substituted Phenanthrolinecopper(I) Complexes

“…Less is known about the impact of electronic effects of these groups although a great many structures have already been exposed in the literature (e.g. alkoxy 24,25 and thioalkoxy, 26 primary and secondary amines, 27 phosphine and phosphine oxide, 28 amide, 29 imidazole and imidazolium, 30 etc.). Let us nevertheless mention the case of a luminescent heteroleptic copper(I) complex where the metal ion is coordinated by the famous diphosphine…”

Substituent-tuned structure and luminescence sensitizing towards Al3+ based on phenoxy bridged dinuclear EuIII complexes

“…The rst transition ( 5 D 0 / 7 F 0 ) observed at the wavelength 581 nm is symmetric, indicating only one type of europium were present in all complexes studied. 21 The second transition ( 5 D 0 / 7 F 1 ) with magnetic dipole nature observed at the wavelength 594 nm. The most intensive maxima correspond to the 5 D 0 / 7 F 2 transition for EuL and EuL 0 are found at wavelength 619 nm.…”