The combination of high efficiencies and long lifetime in a single light‐emitting electrochemical cell (LEC) device remain a major problem in LEC technology, preventing its application in commercial lighting devices. Three green light‐emitting cationic iridium‐based complexes of the general composition [Ir(C^N)2(N^N)][PF6] with 4‐Fppy (2‐(4‐fluorophenyl)pyridinato) as the cyclometalating C^N ligand and 1,10‐phenanthroline (1), 4,7‐diphenyl‐1,10‐phenanthroline (bathophenanthroline, bphen, 2), and 2,9‐dimethyl‐4,7‐diphenyl‐1,10‐phenanthroline (bathocuprione, dmbphen, 3) as ancillary N^N ligands are synthesized and characterized. Computational studies are carried out in order to compare the electronic structure of the three ionic transition metal complexes (iTMCs) and provide insights into their potential as LEC emitter materials. LECs are then fabricated with complexes 1–3. Driven under a pulsed current, they display a high luminance and current and power efficiencies. As the LEC based on complex 2 displays the overall best device performance, including the longest lifetime of 474 h, it is selected for subsequent driving conditions optimization. An extraordinary power efficiency of 25 lm W−1 and current efficiency of 30 cd A−1 are achieved under optimized operation conditions with reduced current density, resulting in a long device lifetime of 720 h. Altogether, ligand design in iTMCs and optimization of the device driving conditions leads to a significant improvement in LEC performance.

A carefully designed red-light-emitting iridium (III) cationic complex yields light-emitting electrochemical cells (LECs) with exceptional efficiency and stability. [Ir­(4Fppy)2(biq)]­[PF6] (4Fppy = 2-(4-fluorophenyl)­pyridinato, biq = 2,2′-biquinoline), whose structure was authenticated by single-crystal X-ray diffraction, emits in the red region of light with photoluminescence (upon 360 nm excitation) and electroluminescence maxima at 629 nm. Astonishingly, it is based on a fluorinated ligand, a design concept more commonly used for green emitter materials. Pairing it with a ligand that has comparatively low-lying frontier orbitals allows for a red shift of the band gap. The uncommon electronic structure of the complex allows overcoming the common problem of strong metal–ligand antibonding interactions in the excited state, rendering it extremely stable under operation. The complex displays a high photoluminescence quantum yield of 27.1% giving rise to an extremely efficient LEC with an initial maximum luminance of 326 cd m–2, current efficiency of 3.26 cd A–1, and power efficiency of 2.27 lm W–1, surpassing the current state of the art. Remarkably, the efficient red LEC has a lifetime of 167 h when driven under a block-wave pulsed current at a frequency of 1000 Hz, an average current density of 100 A m–2, and a duty cycle of 50%. Increasing the duty cycle to 75% led to a decrease in the device average voltage, increasing the power efficiency to an exceptional value of 2.97 lm W–1 without compromising the device stability.

Mixtures of 2,4- and 2,5-disubstituted zirconacyclopentadienes were obtained by the reductive dimerisation of terminal alkynes using the Cp2ZrCl2/lanthanum system. Reactions of dihalophosphines with these mixtures afforded selectively the corresponding 2,4-disubstituted phospholes and 1,4-disubstituted butadienes. A new series of phospholes was characterized by multi-nuclear NMR spectroscopy and X-ray analysis. A possible explanation for the observed selectivity was obtained from X-ray studies and DFT analysis of the intermediate zirconacyclopentadienes.

Ionic liquids – ionic crystals – ionic liquid crystals? Structural order in imidazolium-based ILs, a series of asymmetrical 1-dodecyl-2-methyl-3-alkylimidazolium bromides, [C12C1Cnim][Br] with n = 0–12.