We present the results of our research on the use of microwaves as an unconventional heat source for the acceleration of iridium­(III) chloro-bridged dimer preparation. The results enabled us to revise and improve known guidelines for the very quick and highly efficient synthesis of iridium­(III) dimeric complexes in a very simple isolation manner. According to the developed methodology, the already known dimers containing ligands based on the 2-phenylpyridinato motif, as well as new ones stabilized with functionalized benzo­[h]­quinolinato and 2-phenoxypyridinato-based ligands, were efficiently synthesized. The scope of the incorporated ligands included compounds equipped with electron-donating (−Me, −OMe, −OPh, −NMe2), electron-withdrawing (−F, −Br, −CF3, −C6F5), and hole-transporting (−NPh2, −C6H4NPh2) groups. The obtained complexes were characterized by NMR, X-ray diffraction, and electrospray ionization mass spectrometry methods, and their behavior was examined in the presence of coordinating solvents such as dimethyl sulfoxide and acetonitrile. Investigation of the interactions between the above-mentioned solvents and dimers enabled us to confirm the ability of the former to cleave μ-chloride bridges, which enriches the knowledge in the field of organometallic chemistry. This knowledge can be particularly useful for the scientists working in the field of iridium-based materials, helping to avoid misinterpretation of the spectroscopic data.

The influence and emissive properties of N,O-donating ligands with fluorinated N-aryl moieties on the electronic structure of complexes of the formula [Ir(bzq)2(O∧N)] are reported.

Iridium C,N-cyclometalated complexes with an ionic structure are considered to be promising candidates for application in host/guest solid-state phosphorescent single-layer devices because the employment of such dopants offers the possibility of reducing their concentration in organic matrices as well as allows obtaining organic light emitting devices (OLEDs) with interesting emission parameters. We report herein a methodology enabling the synthesis of cyclometalated ionic iridium(iii) complexes of the type [Ir(C^N)(N^N)]A according to a three-component one-pot strategy involving the acceleration of the reaction via microwave irradiation. The developed protocol allowed efficient synthesis of a series of new cationic iridium(iii) coordination derivatives, which were isolated and spectroscopically characterized, while the structures of two of them were determined by the X-ray method. Moreover, the iridium(iii) derivatives were subjected to the cyclic voltammetry studies in order to determine the energies of the HOMO and LUMO levels as well as to estimate their electrochemical properties and to predict some electronic properties. Additionally, the ONIOM calculation scheme that was used to predict HOMO-LUMO gaps for the studied Ir(iii) complexes showed a good correlation between the experimental and calculated values. In order to determine the influence of the structure and nature of the ancillary ligand on the location of the maximum emission band, the photophysical properties of the synthesized iridium complexes were characterized. Finally, the selected compounds were used as emitters for the construction of polymer light emitting diodes (PLEDs) based on a poly(N-vinylcarbazole)/2-(4-tert-butylphenyl)-5-(4-biphenyl)-1,3,4-oxadiazole (PVK/PBD) matrix. The highest luminance, above 10 000 cd m, was recorded for the device containing only 1.0 wt% of [Ir(bzq)(1,10-phenanthroline)]PF in the PVK/PBD. The fabricated PLEDs exhibit current efficiency in the range of 1.0 to 2.2 cd A.

A series of new bis(benzo[h]quinolinato) Ir(III) complexes with modified β-ketoiminato ancillary ligands were synthesized, and their electrochemical, photophysical properties were determined with the support of theoretical calculations. Moreover, all the synthesized heteroleptic Ir(III) complexes were examined as dopants of the host−guest type emissive layers in solution-processed phosphorescent organic light emitting diodes (PhOLEDs) of a simple structure. As expected on the basis of voltammetry measurements as well as DFT calculations, all the compounds appeared to be green emitters. Their examination showed that alteration of βketoiminato ligand structure causes frontier orbitals' energy levels to be slightly changed, while significantly affecting photoluminescence and electroluminescence efficiencies of iridium phosphors containing these ligands. It was also found that modification of ancillary ligands might enhance charge trapping on the dopant, thus increasing its efficiency, especially in electroluminescence. From among the iridium complexes studied, the compound bearing 1-naphthyl group bonded to the nitrogen atom of the ancillary ligand proved to be the most efficient emitter. The PhOLED fabricated on the basis of this dopant has reached a luminance level of 16000 cd/m 2 , current efficiency close to 12 cd/A, and an external quantum efficiency around 3.2%.

In view of literature reports, benzo [h]quinoline and its substituted analogues, due to their structural similarity to 2-phenylpyridine derivatives, appear to be very promising C,N-cyclometalating ligands for iridium-based Phosphorescent Organic Light Emitting Diode technology. 5-bromo-benzo[h]quinoline aroused our particular interest as a convenient precursor for further transformations, and was successfully functionalized in the course of transition metal-promoted exclusive CÀC, CÀO and CÀN bond formation, yielding a series of 5-substituted benzo[h]quinoline derivatives with unique structures and properties. Some of the synthesized compounds seemed to be appropriate starting materials for subsequent transformations, and enabled the preparation of new benzo[h]quinoline-based materials, for instance those with fluorine or silsesquioxane groups, which have not been synthesized by the conventional Scraup protocol. In selected transformations, the assistance of microwave irradiation as a non-conventional energy carrier significantly improved efficiency, leading to the formation of desired products with yields of up to 99%.