Investigation of oxygen permeation through composites of PMMA and surface-modified ZnO nanoparticles

Oxygen permeabilities of nanocomposite films consisting of poly(methyl methacrylate) (PMMA) and different amounts of spherical zinc oxide (ZnO) nanoparticles were determined to investigate the barrier effect of this material with respect to particle content. A method was applied which is based on quenching of an excited phosphorescent dye by oxygen. Possible effects of the nanoparticles on the response of the dye molecules were investigated and were ruled out

<i>E</i>–<i>Z</i> Photoisomerization in Proton-Modulated Photoswitchable Merocyanine Based on Benzothiazolium and o-Hydroxynaphthalene Platform

The potential of E–Z photoisomerization in molecular organic light-to-thermal conversion and storage in an E–styryl merocyanine system was studied in a polar acidic medium. A photoswitchable styryl merocyanine dye (E)-2-(2-(2-hydroxynaphthalen-1-yl)vinyl)-3,5-dimethylbenzo[d]thiazol-3-ium iodide was synthesized for the first time. The reversible E–Z photoisomerisation of the dye was investigated using UV-Vis spectroscopy and DFT calculations. E–Z isomerization was induced through the use of visible light irradiation (λ = 450 nm). The obtained experimental and theoretical results confirm the applicability of the Z and E isomers for proton-triggered light harvesting

(<i>E</i>)-3-Heptyl-2-(4-thiomorpholinostyryl)benzo[d]thiazol-3-ium Iodide as Solvatochromic and Fluorogenic Dye for Spectroscopy Applications

The development of new selective fluorogenic probes for monitoring microbiological objects and cellular compartments may help to determine the mechanism of pathogenesis of new pathogens in living cells. The easy and reliable synthetic strategy for the direct preparation of chemically pure styryl dye (E)-3-heptyl-2-(4-thiomorpholinostyryl)benzo[d]thiazol-3-ium iodide is described. The photophysical properties in different solvents and in water medium neat and in the presence of the dsDNA and RNA of the dye is demonstrated and compared with that of the known structure analogue. The cellular uptake and the ability to bind cell organelles is determined. The introduction of a heptyl substituent attached to the quaternary nitrogen atom of the benzothiazole ring leads to an improvement in the photophysical properties of the dye

Low-threshold amplified spontaneous emission in thin films of poly(tetraarylindenofluorene)

Funding text The authors acknowledge financial support by the German Ministry of Science and Education, Project OLAS, 13N8168. One of the authors (F.L.) wishes to thank the Fonds der Chemischen Industrie for providing a Kekulé scholarship. The authors acknowledge experimental assistance from H. Menges.We report on amplification of blue light (469 nm) via amplified spontaneous emission in asymmetric planar waveguides of a fully arylated polyindenofluorene derivative. A very low threshold value of about 3 μJ cm2 (∼375 W cm2) for amplification of light has been demonstrated by pumping the waveguides at 3.0 eV (410 nm) with a stripe shape excitation beam. Moderate gain coefficients up to 21 cm-1 and loss coefficients around 6 cm-1 have been measured. All measurements were performed under ambient conditions. No sample degradation could be observed which testifies to the excellent stability of the material against photodegradation. © 2005 American Institute of Physics

Thermally stable blue emitting terfluorene block copolymers

Spectroscopic and morphological studies on a series of rod-coil block copolymers containing terfluorene segments as the rigid blocks and polystyrene as the flexible parts demonstrate an increase in the photoluminescence intensity and the exciton lifetime as well as formation of isolated spheres as thin films upon thermal annealing in air (200 degrees C for 30 min). Moreover, no appearance of the low energy emission band centered at 520 nm was found after the same thermal treatment which permits these copolymers to emit pure blue light

Correction to “Electron-Exchange Assisted Photon Energy Up-Conversion in Thin Films of π-Conjugated Polymeric Composites”

The mechanism of triplet-triplet annihilation (TTA)-induced up-converted (UC) delayed luminescence is studied in two different binary organic systems consisting of platinum(II) octaethyl porphyrin (PtOEP) mixed with either poly(fluorene) (PF26) or ladder-type pentaphenylene (L5Ph). Cyclic voltammetry and differential pulse voltammetry are employed for estimating the ionization potentials of PtOEP and L5Ph. Delayed luminescence spectroscopy sets the energy of the lowest excited triplet state of L5Ph 0.20 eV higher than the triplet state of PtOEP (1.90 eV). The different phosphorescence PtOEP lifetime indicates differences in PtOEP aggregation in the polymer matrices. The presented results propose that the difference in the relative intensities of the delayed UC luminescence is determined by the difference between the ionization potentials of PtOEP and the polymer matrix. In the solid state, the electric-field-induced quenching of the delayed L5Ph UC luminescence suggests the formation of an intermediate charge-transfer state after the TTA within the PtOEP domains