Marina A. Katkova

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.

Electroluminescent characteristics of scandium and yttrium 8-quinolinolates

Efficient electroluminescence (EL) was obtained in organic light-emitting devices using 8-quinolinolate complexes of scandium (Scq3) and yttrium (Yq3) as emitters. Compared to the device based on the analogous Alq3 complex, no notable difference in the EL performances of the Yq3 device can be found; however, the EL characteristics of device with Scq3 were significantly enhanced. The device with the configuration of indium tin oxide/ N,N′-bis(3-methylphenyl)-N,N′-diphenylbenzidine/Scq3/Yb exhibits a maximum current efficiency of 4.6 cd/A and a maximum power efficiency of 2.6 lm/W at a luminance of 300 cd/m2. The improvement of the performance of this device should be attributed to the higher hole mobility of the Scq3 as compared to Alq3 or a smaller barrier for hole injection into Scq3 compared to Alq3.

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.

New cathode materials for organic light-emitting diodes: Tm:Yb and Eu:Yb

Performance characteristics of organic light-emitting diodes (OLEDs) with mono-(Al, Sm, Tm, Yb) and bimetallic (Ca:Al, Eu:Yb, Tm:Yb) cathodes are compared. It is shown that OLEDs with the Tm:Yb cathodes are the best of the studied devices in terms of the turn-on voltage, operating voltage, current efficiency, and luminance efficiency.

Quantum chemical study of formation of CuII–YIII metallamacrocyclic complexes based on glycinehydroximate ligands

The process of solution-phase formation of the CuII–YIII 15-metallacrown-5 complexes bearing the glycinehydroximate ligands has been for the first time investigated by methods of quantum chemistry. The DFT modeling at the B3LYP/DGDZVP (PCM) level was carried out for mono-, bi-, and tri-nuclear copper(II) complexes and also for heteronuclear CuII–YIII derivatives as the metallamacrocycle precursors. The dependence of relative stability of these complexes on the CuII and YIII coordination surroundings and also on the mutual positions of ligands was found. The structural (variations of interatomic distances and valence angles), electronic (changes in the atomic charges and electron density), and thermodynamical (enthalpies and Gibbs free energies) regularities of 15-metallacrown-5 formation were revealed. The key role of YIII cation was established for the process of formation of the polynuclear metallamacrocyclic compound (15-metallacrown-5).

Synthesis and X-Ray Structure of 1,3,5-Tri(phenylethynyl)benzene

Abstract 1,3,5-Tri(phenylethynyl)benzene 1 obtained by coupling triiodobenzene with phenylacetylene shows an unusual non planar molecular structure.