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Transition-metal complexes in organic light-emitting diodes (OLEDs) can overcome the efficiency limit of fluorescent devices. Due to the strong spin-orbit coupling of these complexes, both singlet and triplet excitons can be harvested and an internal quantum efficiency of 100 % is possible.[1-3] Many complexes with transition-metals, such as iridium, ruthenium, osmium and platinum have been synthesized to develop highly efficient phosphorescent OLEDs (PHOLEDs), [4][5][6][7][8] because a simple ligand-variation allows for a wide range of emission-colors and for tuning of the chemical properties.

Keywords: Electrospray mass spectrometry / Radical molecular ions / Even electron rule / Reaction mechanism studies by ESI-MS/MSThe ion formation mechanism in electrospray MS is reviewed, with special focus on the electrochemical red/ox reactions responsible for the formation of radical molecular ions. Prerequisites influencing the likelihood of formation and observation of a particular compound as an open-shell molecular species in ESI-MS (i.e., the structure and the oxidation potential of the analyte, the solvent and additives) are evaluated. For illustration of the ESI phenomena governing radical cation formation, an ESI-MS study of tetra(aryl)-benzidine compounds is presented. The facile formation of abundant radical molecular cations in ESI-MS demonstrates imposingly that the basicity of the analyte's nitrogen atoms is strongly overcompensated by the ability to stabilize unpaired electrons. ESI-MS n spectra of the tetra(aryl)benzidine molecular ions exhibit a characteristic feature in the loss of radicals. This process is the major fragmentation pathway of open-shell molecular precursor ions in their MS 2 spectra, and

Enlightening the memory: The integration of a crosslinkable photochromic dithienylperfluorocyclopentene (DTE) into organic light-emitting diodes (OLED) allows for the individualization of the emissive area of the OLED device, for example, for signage applications. The operation principle is based on switching the injection barrier for holes (positive charge carriers). Very large ON/OFF ratios of up to 3000 for current as well as electroluminescence have been achieved.