Tatyana V. Balashova

Near-infrared electroluminescent lanthanide [Pr(III), Nd(III), Ho(III), Er(III), Tm(III), and Yb(III)] N,O-chelated complexes for organic light-emitting devices

New near-IR electroluminescent complexes of Pr3+, Nd3+, Ho3+, Er3+, Tm3+, Yb3+ with N,O-chelated ligands, Ln2(OON)6 (OON = 2-(2-benzoxyazol-2-yl)phenolate) and Ln2(SON)6 (SON = 2-(2-benzothiazol-2-yl)phenolate), were synthesized by the reaction of Ln[N(SiMe3)2]3 and the corresponding N,O-chelating ligand. X-Ray analysis for the Pr and Nd compounds reveals centrosymmetric dimeric structures of the complexes. The solid-state electronic absorption spectra and the electroluminescent spectra show long-wavelength 4f–4f transitions which provide potential use of the compounds as NIR emitting materials in organic light-emitting devices (OLEDs). When constructing OLEDs based on Ln2(OON)6 and Ln2(SON)6, the best results were achieved with the Nd3+ and Yb3+ complexes, where the NIR wall plug efficiency of the ITO/TPD/Ln-complex/BATH/Yb system is 0.82 and 1.22 mW W−1, respectively.

Lanthanide complexes with substituted naphtholate ligands: extraordinary bright near-infrared luminescence of ytterbium

A series of Pr, Nd, Ho, Er, Tm, and Yb complexes with 3-(2-benzoxazol-2-yl)-2-naphtholate and 3-(2-benzothiazol-2-yl)-2-naphtholate ligands was synthesized. The structure, as well as the photo- and electroluminescent properties of these complexes were studied. An extraordinary bright emission of Yb3+ was detected. To explain the phenomenon, a novel excitation mechanism involving intramolecular electron transfer was proposed.

Lithium, zinc and scandium complexes of phosphorylated salicylaldimines: synthesis, structure, thermochemical and photophysical properties, and application in OLEDs

The reaction of phosphorylated salicylaldimines containing the PO group either directly attached to the central benzene core (1a) or connected with it via a methylene unit (1b) with lithium and scandium hexamethyldisilazides readily afforded [κ3-O,N,O-(L–H)Li]2 (2a,b) and [κ2-O,N-(L–H)3Sc] (3a,b) (L – ligand) complexes in high yields. The treatment of 1b with Et2Zn in the presence of 1,10-phenanthroline led to zinc(II) complex 4b of (L–H)2Zn(phen) composition featuring a bidentate coordination mode of both salicylaldiminate ligands without participation of the phosphoryl groups. The structures of the complexes obtained were confirmed by the IR spectroscopic data and, in some cases, X-ray diffraction analysis. The thermal behavior of compounds 1a,b and 4b was studied by DSC. The temperature dependences of saturated vapor pressures of ligands 1a,b and complexes 2a, 4b were measured by the Knudsen effusion method. The thermodynamic parameters characterizing crystal-to-gas phase transitions were calculated. The complexes obtained were shown to possess weak photoluminescence in THF solution at room temperature. The unoptimized three-layer OLEDs based on 2a,b and 3a,b emit green light of low and moderate intensity.

Anhydrous mono- and dinuclear tris(quinolinolate) complexes of scandium: the missing structures of rare earth metal 8-quinolinolates

The first monomeric anhydrous scandium tris(8-quinolinolate) complex 1 with the 2-amino-8-quinolinolate ligands and the Sc(2)Q(6) dinuclear complex 2 with the unsubstituted 8-quinolinolate ligands have been synthesized and characterized by X-ray analysis and DFT calculations. The intramolecular hydrogen bonds appear to be responsible for the unique monomeric structure of complex 1. The DFT-based analysis of the electron density topology reveals the (3,-1) critical points corresponding to the O···H and N···H bonds. The two scandium atoms in compound 2 are inequivalent due to different ligand surroundings. They are coordinated by seven (5O, 2N) and eight (4O, 4N) ligand atoms. The increase in the coordination number is accompanied by a decrease in the positive charge of the metal atom as evidenced by the DFT calculations.

Diastereoselective formation of calcium and ytterbium ansa-metallocenes via recombination of guaiazulene (Gaz) radical anions. Molecular structure of ansa-(η5-Gaz)2Ca(THF)2 and ansa-(η5-Gaz)2Yb(Py)2 (Gaz = 1,4-dimethyl-7-isopropylazulene) complexes

Abstractansa-Metallocene derivative (η5-Gaz)2Ca(THF)2 (1) (Gaz = 1,4-dimethyl-7-isopropylazulene) was synthesized by the reaction of CaI2(THF)2 with two equivalents of potassium and two equivalents of guaiazulene in THF. The ytterbium analog ansa-(η5-Gaz)2Yb(THF)2 (2a) was synthesized by the reduction of guaiazulene with ytterbium naphthalenide in THF. The recrystallization of 2a from pyridine leads to the exchange of the coordinated solvent molecules and gives ansa-(η5-Gaz)2Yb(NC5H5)2 (2b). The molecular structures of 1, 2a, and 2b were determined by X-ray diffraction analysis. The crystals of 1, 2a, and 2c consist of a racemic mixture of both R,R- and S,S-enantiomers. The calcium and ytterbium atoms η5-coordinate the five-membered rings of the guaiazulene ligands. The 1H NMR spectroscopic and X-ray diffraction data unambiguously confirm the exclusive formation of N2-symmetric ansa-metallocenes in these reactions. The reaction of compound 1 with Me3SiCl in THF occurs with retention of the N—N bond between two guaiazulene moieties and affords bis(1,4-dimethyl-3-trimethylsilyl-7-isopropylazulene) (3) in high yield.

Substituted naphtholates of rare earth metals as emissive materials

The synthesis, characterization, photoluminescent (PL) and electroluminescent (EL) behavior of trivalent Sc, Nd, Gd, Er, Tm and Yb complexes with 3-(5-methylbenzoxazol-2-yl)naphthol (L-5Me) and 3-(6-methylbenzoxazol-2-yl)naphthol (L-6Me) ligands are reported. An X-ray analysis of Sc(L-5Me)3, Sc(L-6Me)3 as well as the non-methylated analogue Sc(L)3 has shown the monomeric structure of the complexes whereas the lanthanide naphtholates according to LDI-TOF data are dimers Ln2(L-5Me)6 and Ln2(L-6Me)6. The scandium complexes under photo- and electroexcitation revealed intense ligand-centered luminescence peaked at 522 nm. The PL and EL spectra of Nd, Tm and Yb compounds displayed moderate ligand-centered emission along with narrow bands of corresponding f–f transitions.

ate complexes of lanthanides with aryloxide ligands: Synthesis, structures, and luminescence properties

Abstract(2-Benzox(thi)azol-2-yl)phenolate and -naphtholate ate complexes of Sc, Y, La, Sm, Tb, and Yb are synthesized. The structure of (benzoxazolyl)phenolate complexes of La, Sm, and Yb are determined by X-ray diffraction analysis. All synthesized compounds manifest ligand-centered photo- and electroluminescence in a range of 510–540 nm. In addition, the spectra of the samarium and terbium complexes exhibit narrow bands of f-f transitions characteristic of Sm3+ and Tb3+ ions.

Lanthanide complexes with the Schiff base containing sterically hindered phenol: Synthesis, structure, and luminescence properties

The syntheses of the 2,6-di-tert-butyl-4-(2-hydroxybenzylideneamino)phenolate (L) complexes of Gd (I), Nd (II), Er (III), Yb (IV), Tm (V), Sm (VI), and Tb (VII) are described. The structures of the Gd and Er complexes are determined by X-ray diffraction analysis (CIF files CCDC nos. 1558820 (I) and 1558819 (III)). All synthesized compounds exhibit ligand-centered photoluminescence in a range of 405–485 nm. In addition, the luminescence spectra of solid samples of the neodymium and ytterbium complexes contain narrow bands of f–f transitions characteristic of Nd3+ and Yb3+ ions.

Specifics of luminescence of (benzoxazolyl)phenolate and (benzothiazolyl)naphtholate heterometallic Zn, Sc, Nd, Sm, Er, and Yb complexes

Heterometallic complexes Ln(L1)5Zn (Ln = Sc, Sm, Gd) were obtained by the reactions of silylamides Ln[N(SiMe)2]3 with 2-(benzoxazol-2-yl)phenol (HL1) in the presence of diethylzinc. Similar reactions with 3-(benzothiazol-2-yl)-2-naphthol (HL2) led to the formation of complexes Ln(L2)5Zn (Ln = Nd, Er, Gd, Yb). The introduction of the zinc-containing fragments provided a considerable increase of photo- and electroluminescence intensity of the scandium complex.

Reactions of alkyl compounds of zinc, cadmium, and gallium with dysprosium, neodymium, and thulium diiodides

The ethyl complexes of dysprosium DyI2Et(DME)2 and DyIEt2(DME)2 were synthesized by the reaction of DyI2 with ZnEt2 in dimethoxyethane. The complexes were isolated as pale yellow crystals. According to the X-ray diffraction data, these compounds contain, in addition to DyI2Et(DME)2 and DyIEt2(DME)2, triiodide DyI3(DME)2 (1). The reactions of CdMe2 with NdI2, DyI2, and TmI2 proceed in a similar way and afford methyl iodide complexes of lanthanides. The reaction of GaEt3 with DyI2 gave the ionic complex of trivalent dysprosium [GaEt4]−[DyI2(THF)5]+ (2).