title: 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 transitions5D0→7FJ(J = 0-6). The value of deviation of the components of5D0→7F2and5D0→7F1transitions 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 NO3counter-ions than for complexes with phenanthroline-based ligands and NO3counter-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.
authors.affiliation: Department of Chemistry, M.V. Lomonosov Moscow State University 1/3 Leninskie Gory, 119991 Moscow, Russian Federation. borisova.nataliya@gmail.com and N.A. Nesmeyanov Institute of Organoelement Compounds, 28 Vavilov Str., Moscow, Russian Federation. kostya@xray.ineos.ac.ru.
authors.forename: Nataliya E
authors.identifier: http://orcid.org/0000-0002-0789-5391
authors.initials: NE
authors.lastname: Borisova
authors.affiliation: Department of Chemistry, M.V. Lomonosov Moscow State University 1/3 Leninskie Gory, 119991 Moscow, Russian Federation. borisova.nataliya@gmail.com and Faculty of Physics, Lomonosov Moscow State University, 1/2 Leninskie Gory, 119991 Moscow, Russian Federation. harcheva.anastasiya@physics.msu.ru.
authors.forename: Anastasia V
authors.initials: AV
authors.lastname: Kharcheva
authors.affiliation: Faculty of Physics, Lomonosov Moscow State University, 1/2 Leninskie Gory, 119991 Moscow, Russian Federation. harcheva.anastasiya@physics.msu.ru.
authors.forename: Svetlana V
authors.initials: SV
authors.lastname: Patsaeva
authors.affiliation: Department of Chemistry, M.V. Lomonosov Moscow State University 1/3 Leninskie Gory, 119991 Moscow, Russian Federation. borisova.nataliya@gmail.com.
authors.forename: Leonid A
authors.initials: LA
authors.lastname: Korotkov
authors.affiliation: Department of Chemistry, M.V. Lomonosov Moscow State University 1/3 Leninskie Gory, 119991 Moscow, Russian Federation. borisova.nataliya@gmail.com.
authors.forename: Sergey
authors.initials: S
authors.lastname: Bakaev
authors.affiliation: Department of Chemistry, M.V. Lomonosov Moscow State University 1/3 Leninskie Gory, 119991 Moscow, Russian Federation. borisova.nataliya@gmail.com.
authors.forename: Marina D
authors.initials: MD
authors.lastname: Reshetova
authors.affiliation: N.A. Nesmeyanov Institute of Organoelement Compounds, 28 Vavilov Str., Moscow, Russian Federation. kostya@xray.ineos.ac.ru.
authors.forename: Konstantin A
authors.initials: KA
authors.lastname: Lyssenko
authors.affiliation: A.N. Frumkin Institute of Physical Chemistry and Electrochemistry, RAS 31 Leninsky prospect, 119071 Moscow, Russian Federation. mar@ipc.rssi.ru.
authors.forename: Elena V
authors.initials: EV
authors.lastname: Belova
authors.affiliation: A.N. Frumkin Institute of Physical Chemistry and Electrochemistry, RAS 31 Leninsky prospect, 119071 Moscow, Russian Federation. mar@ipc.rssi.ru.
authors.forename: Boris F
authors.initials: BF
authors.lastname: Myasoedov