Synthesis, X-ray Structural Characterization, and DFT Calculations of Mononuclear Nickel(II) Complexes Containing Diamine and Methacrylate Ligands.

The mononuclear Ni(II) complexes [Ni(en)2(H2O)2](MAA)2 (1) and [Ni(pn)2(MAA)2] (2), where MAA, en and pn are methacrylate, ethylendiamine and 1,3-propylendiamine, respectively, have been synthesized and characterized by elemental analysis, FT-IR and UV�Vis spectroskopy. Structures of the complexes have been determined by single-crystal X-ray diffraction analyses. In the nickel(II) complexes 1 and 2 nickel(II) ion is six-coordinate and has a distorted octahedral geometry. Ni(II) is bonded to four nitrogen atoms of the two diamines and additionally to two oxygen atoms of aqua ligand in 1, and two oxygen atoms of methacrylate ligands in 2. The theoretical geometries of the studied compounds have been calculated by means of density functional theory (DFT) at the B3LYP/6-311+G(d,p)/LanL2DZ level and considering effective core potential (ECP). The comparison of the results indicates that the employed DFT method yields good agreement with experimental data.

Phenanthroimidazole as molecularly engineered switch for efficient and highly long-lived light-emitting electrochemical cell.

Light-emitting electrochemical cells (LECs) based on Ir(III) complexes owing to the superior advantages exhibit high potential for display and lighting applications. Herein, a series of Ir(III) complexes based on phenanthroimidazole (PI) as an ancillary ligand were synthesized to achieve efficient and highly stable yellow-to-orange LEC devices with fast response. These complexes exhibit appropriate electrochemical stability and significant suppression of concentration quenching in the thin films compared to the archetype complex. The fabricated LECs showed remarkably long device lifetimes over 1400 and 2100 h and external quantum efficiency of 2 and 3% for yellow and orange-LECs, respectively. The obtained t1/2 for yellow LEC is much higher than archetype [Ir(ppy)2(phen)]+ and their phenanthroline-based analogues reported so far. The incorporation of an ionic tethered functional group on PI, improved the mobility of the emissive layer and reduced the device turn-on time by 75-88%. This study shows a facile functionalization and characterization of the PI ligand as well as its potential application in optoelectronic devices (OLED).