Perylene-3,4:9,10-bis(dicarboximides) (PBIs) rank among the most important functional dyes and organic semiconductors but only recently their radical anions and dianions attracted interest for a variety of applications. Here, we systematically...

{Ag2 (12-C≡C-closo-1-CB11 H11 )}n and selected pyridine ligands have been used for the synthesis of photostable Ag(I) clusters that, with one exception, exhibit for Ag(I) compounds unusual room-temperature phosphorescence. Extraordinarily intense phosphorescence was observed for a distorted pentagonal bipyramidal Ag(I) 7 cluster that shows an unprecedented quantum yield of Φ=0.76 for Ag(I) clusters. The luminescence properties correlate with the structures of the central Ag(I) n motifs as shown by comparison of the emission properties of the clusters with different numbers of Ag(I) ions, different charges, and electronically different pyridine ligands.

A series of perylene bisimide (PBI) dyes bearing various aryl substituents in 1,6,7,12 bay positions has been synthesized by Suzuki cross‐coupling reaction. These molecules exhibit an exceptionally large and conformationally fixed twist angle of the PBI π‐core due to the high steric congestion imparted by the aryl substituents in bay positions. Single crystal X‐ray analyses of phenyl‐, naphthyl‐ and pyrenyl‐functionalized PBIs reveal interlocked π‐π‐stacking motifs, leading to conformational chirality and the possibility for the isolation of enantiopure atropoisomers by semipreparative HPLC. The interlocked arrangement endows these molecules with substantial racemization barriers of about 120 kJ mol−1 for the tetraphenyl‐ and tetra‐2‐naphthyl‐substituted derivatives, which is among the highest racemization barriers for axially chiral PBIs. Variable temperature NMR studies reveal the presence of a multitude of up to fourteen conformational isomers in solution that are interconverted via smaller activation barriers of about 65 kJ mol−1. The redox and optical properties of these core‐twisted PBIs have been characterized by cyclic voltammetry, UV/Vis/NIR and fluorescence spectroscopy and their respective atropo‐enantiomers were further characterized by circular dichroism (CD) and circular polarized luminescence (CPL) spectroscopy.

We have used a quartz crystal microbalance to study the dynamical properties of thin films of solid nitrogen adsorbed on a lead substrate in the temperature range 4 KϽTϽ14 K. Simple mechanical models relate the frequency shift and the Q of the microbalance to the friction at the N 2 /Pb interface. By varying either the magnetic field or the temperature, the Pb substrate could be prepared in the superconducting or normal state. Our experiments indicate that superconductivity has no effect on the behavior of the microbalance. Furthermore, experiments in which the N 2 layer thickness was varied by in situ evaporation showed that solid nitrogen films are rigidly pinned on our low-temperature substrate for velocities below approximately 0.6 m/sec.

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