Photophysical properties of thin films and solid phase of switchable supermolecular anthracene-based rotaxanes

Polycrystalline powders and thin films of a novel rotaxane, methyl-exopyridine-anthracene rotaxane (EPAR-Me), and of the related thread and stoppers 10-[3,5-di (ter butyl)phenoxy]decyl-2-({2-[(9-anthrylcarbonyl) amino] acetyl}amino) acetate (ANTPEP), have been characterised by photoluminescence, absorption and photoluminescence excitation spectroscopy. A rather unusual, i.e. unstructured and largely red-shifted, photoluminescence spectral behaviour of the rotaxane has been found. Preliminary time resolved measurements indicate a fast energy transfer from the anthracene unit to different species the nature of which is still not assigned.

Site-Selektive Laserspektroskopie an amorphen Festkoerpern bei tiefen Temperaturen

SIGLEAvailable from TIB Hannover: DW 5342 / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman

Lasing Supraparticles Self-Assembled from Nanocrystals

One of the most attractive commercial applications of semiconductor nanocrystals (NCs) is their use in lasers. Thanks to their high quantum yield, tunable optical properties, photostability, and wet-chemical processability, NCs have arisen as promising gain materials. Most of these applications, however, rely on incorporation of NCs in lasing cavities separately produced using sophisticated fabrication methods and often difficult to manipulate. Here, we present whispering gallery mode lasing in supraparticles (SPs) of self-assembled NCs. The SPs composed of NCs act as both lasing medium and cavity. Moreover, the synthesis of the SPs, based on an in-flow microfluidic device, allows precise control of the dimensions of the SPs, i.e. the size of the cavity, in the micrometer range with polydispersity as low as several percent. The SPs presented here show whispering gallery mode resonances with quality factors up to 320. Whispering gallery mode lasing is evidenced by a clear threshold behavior, coherent emission, and emission lifetime shortening due to the stimulation process

Optical and electroemission properties of thin films of supermolecular anthracene-based rotaxanes

Rotaxanes are a new class of functional materials. They consist of mechanically interlocked supermolecular systems where a central linear thread passes through the cavity of a macrocyclic ring. The ring is constrained within the two extremities of the thread by two bulky stoppers. In this work, we report on spectroscopic characterisation of an anthracene-based novel rotaxane (EPAR-Me) and on the electroemission (EL) from a basic rotaxane component (ANTPEP). An OLED has been prepared using the anthracene-based thread (ANTPEP) of the EPAR-Me rotaxane in polycarbonate matrices. Spectroscopic measurements are reported, supporting excimer-like EL and field dependent electroexcimer for the ANTPEP thin film. Tentative assignment of emitting species of EPAR-Me are also discussed.