Cyanines: Direct Functionalization, Oligomerization, linear and nonlinear optical Properties

Die organische Farbstoffklasse der Polymethine zeigt ein beträchtliches Potential in ihren linear und nichtlinear optischen (NLO) Eigenschaften. Sie sind u.a. für den Einsatz als aktive Medien in photonischen Bauelementen prädestiniert. Die kationischen Vertreter der Polymethinfarbstoffe, die Cyanine, zeigen sehr hohe lineare Polarisierbarkeiten a und nichtlineare Polarisierbarkeiten dritter Ordnung g. Infolge dieser hohen Nichtlinearitäten eignen sich die Cyanine beispielsweise als Materialien zur Frequenzkonversion von Licht oder als Medien in optischen Hochgeschwindigkeitsschaltern. Durch gezielte Funktionalisierungen können, wie gezeigt wird, die an sich schon hohen NLO-Aktivitäten von Cyaninen noch gesteigert werden. In der vorliegenden Arbeit werden u.a. die direkten Funktionalisierungen durch Halogene und deren Substitutionen durch p-Systeme mittels Kreuzkupplungsreaktionen an den heterozyklischen Endgruppen und an den Methinketten von Indo-, Indocarbo- und Indodicarbocyaninen diskutiert. Zusätzlich werden die Synthesen zur Präparation von oligomeren Cyaninen mit p-Brücken vorgestellt. Auch die Herstellung und Untersuchung einiger Cyaninfarbstoffe mit Benzothiazolendgruppen wird betrachtet. Die NMR-spektroskopisch und kristallographisch durchgeführten konformeren Strukturaufklärungen von Cyaninen werden berechneten Daten gegenübergestellt. Reaktionen in kondensierter Phase weisen sich als ein besonderes massenspektrometrisches Verhalten einiger synthetisierter Cyanine im FAB-Experiment aus. Die systematische Variation der p-Substituenten in den monomeren und der p-Brücken in den oligomeren Cyaninen sowie die daraus resultierenden Änderungen der linear und nichtlinear optischen Eigenschaften dieser Farbstoffe werden ausführlich beschrieben und diskutiert.The polymethines as class of organic dyes show a great potential in nonlinear optical (NLO) properties and are very promising for applications as active media in photonics. The cationic class of polymethines, the cyanine dyes, show a high molecular polarizability a and nonlinear third order polarizability g. This high nonlinearity makes cyanines very interesting as materials for e.g. frequency conversion or optical high-speed switches. Specific functionalization leads to an increase to even higher NLO activities of cyanines. This work reports the direct functionalization of indo-, indocarbo- and indodicarbocyanines with halogens and their subsequent substitution by p-systems via cross-coupling reactions in endgroups and methine chains. Additionally, synthesis routes for oligomeric cyanines with p-bridges are demonstrated. Cyanine dyes with benzothiazol endgroups are synthesized and investigated, as well. Conformational behaviour of cyanines is determined by NMR-spectroscopy and x-ray analysis and results are compared with calculations. The reaction of some synthesized cyanines in mass spectrometric FAB-experiments are explained as reaction in condensed phase. The p-substituents in the monomeric and the p-bridges in the oligomeric cyanines are systematically modified. The resulting changes in linear and nonlinear optical properties of this dyes are reported in detail

Boknis Eck Time Series Station (SW Baltic Sea): Measurements from 1957 to 2010

Salinity, temperature, and O2 have been recorded on a monthly basis at the Boknis Eck Time Series Station (BE; Eckernförde Bay, SW Baltic Sea) since April 1957 with only two major breaks (1976-78 and 1983-1985). Chlorophyll a measurements started in 1960 and nutrient data (NO2-, NO3-, NH4+, PO4 3-, SiO4 2-) are available since March 1979. Here we present a short introduction to the long-term trends observed at BE and selected results of ongoing projects covering different topics from the surface microlayer and the water column to the sediments at BE. On the basis of a preliminary analysis of the long-term records of surface water temperature, oxygen in 25m, and dissolved nutrients we conclude that BE is affected by both regional processes and global processes detectable as eutrophication and warming of the surface water, respectively. The number of events with extremely depleted O2 concentrations (hypoxia/anoxia) in the bottom layer has been increasing during the last 25 years. Moreover, BE is site of signifi cant emissions of climate relevant trace gases such as methane

Single-Mode Polymer Ridge Waveguide Integration of Organic Thin-Film Laser

Organic thin-film lasers (OLAS) are promising optical sources when it comes to flexibility and small-scale manufacturing. These properties are required especially for integrating organic thin-film lasers into single-mode waveguides. Optical sensors based on single-mode ridge waveguide systems, especially for Lab-on-a-chip (LoC) applications, usually need external laser sources, free-space optics, and coupling structures, which suffer from coupling losses and mechanical stabilization problems. In this paper, we report on the first successful integration of organic thin-film lasers directly into polymeric single-mode ridge waveguides forming a monolithic laser device for LoC applications. The integrated waveguide laser is achieved by three production steps: nanoimprint of Bragg gratings onto the waveguide cladding material EpoClad, UV-Lithography of the waveguide core material EpoCore, and thermal evaporation of the OLAS material Alq3:DCM2 on top of the single-mode waveguides and the Bragg grating area. Here, the laser light is analyzed out of the waveguide facet with optical spectroscopy presenting single-mode characteristics even with high pump energy densities. This kind of integrated waveguide laser is very suitable for photonic LoC applications based on intensity and interferometric sensors where single-mode operation is required

A2BC-Type Porphyrin SAM on Gold Surface for Bacteria Detection Applications: Synthesis and Surface Functionalization

Currently used elaborate technologies for the detection of bacteria can be improved in regard to their time consumption, labor intensity, accuracy and reproducibility. Well-known electrical measurement methods might connect highly sensitive sensing systems with biological requirements. The development of modified sensor surfaces with self-assembled monolayers (SAMs) from functionalized porphyrin for bacteria trapping can lead to a highly sensitive sensor for bacteria detection. Different A2BC-type porphyrin structures were synthesized and examined regarding their optical behavior. We achieved the synthesis of a porphyrin for SAM formation on a gold surface as electrode material. Two possible bio linkers were attached on the opposite meso-position of the porphyrin, which allows the porphyrin to react as a linker on the surface for bacteria trapping. Different porphyrin structures were attached to a gold surface, the SAM formation and the respective coverage was investigated

8-(Biphenyl-2-yl)-7,9-diphenyl-8H-cyclo­penta­[a]acenaphthylen-8-ol

In the title compound, C39H26O, the cyclo­penta­[a]acenaphthyl­ene skeleton displays the expected distortions, with formal sp 2 bond angles as high as C—C—C = 142.50 (10)°. The OH group forms inter­molecular hydrogen bonds via x-axis translation to the centroid (Cg) of the pendant phenyl ring of the biphenyl system, with H⋯Cg = 2.41 Å and O—H⋯Cg = 153°

Homogeneous Distribution of Polymerizable Coumarin Dyes for Active Few Mode POF

For most kinds of active polymer optical fibers, a homogeneous distribution of dye molecules over the entire fiber length and cross section is required. In this study, chemical bonding of dyes to poly(methyl methacrylate) (PMMA) by copolymerization is achieved within the polymerization process instead of dissolving the dyes in the monomers. In combination with an improved fabrication mechanism, this leads to homogeneous dye distribution within the preforms. A method for proving the integration of the dyes into the polymer chains has been developed using high-performance liquid chromatography (HPLC) and size exclusion chromatography (SEC). Prestructured core-cladding preforms with dye-doped poly(cylohexyl methacrylate-co-methyl methacrylate)-core have been prepared with the Teflon string technique and were heat-drawn to few mode fibers

mer-Bis[2-(1,3-benzothiazol-2-yl)phenyl-κ2 C 1,N][3-phenyl-5-(2-pyridyl)-1,2,4-triazol-1-ido-κ2 N 1,N 5]iridium(III) deuterochloro­form 3.5-solvate

In the title compound, [Ir(C13H9N4)(C13H8NS)2]·3.5CDCl3, the coordination at iridium is octa­hedral, but with narrow ligand bite angles. The bond lengths at iridium show the expected trans influence, with the Ir—N bonds trans to C being appreciably longer than those trans to N. The chelate rings are mutually perpendicular, the inter­planar angles between them all lying within 6° of 90°. All ligands are approximately planar; the maximum inter­planar angles within ligands are ca 10°. The three ordered deuterochloro­form mol­ecules are all involved in C⋯D—A contacts that can be inter­preted as hydrogen bonds of various types. The fourth deuterochloroform is disordered over an inversion centre

Upconversion nanocrystal doped polymer fiber thermometer

In recent years, lanthanide-doped nanothermometers have been mainly used in thin films or dispersed in organic solvents. However, both approaches have disadvantages such as the short interaction lengths of the active material with the pump beam or complicated handling, which can directly affect the achievable temperature resolution. We investigated the usability of a polymer fiber doped with upconversion nanocrystals as a thermometer. The fiber was excited with a wavelength stabilized diode laser at a wavelength of 976 nm. Emission spectra were recorded in a temperature range from 10 to 35◦C and the thermal emission changes were measured. Additionally, the pump power was varied to study the effect of self-induced heating on the thermometer specifications. Our fiber sensor shows a maximal thermal sensitivity of 1.45%/K and the minimal thermal resolution is below 20 mK. These results demonstrate that polymer fibers doped with nanocrystals constitute an attractive alternative to conventional fluorescence thermometers, as they add a long pump interaction length while also being insensitive to strong electrical fields or inert to bio-chemical environments. © 2020 by the authors. Licensee MDPI, Basel, Switzerland

Methacrylate-Based Copolymers for Polymer Optical Fibers

Waveguides made of poly-methyl-methacrylate (PMMA) play a major role in the homogeneous distribution of display backlights as a matrix for solid-state dye lasers and polymer optical fibers (POFs). PMMA is favored because of its transparency in the visible spectrum, low price, and well-controlled processability. Nevertheless, technical drawbacks, such as its limited temperature stability, call for new materials. In this work, the copolymerization technique is used to modify the properties of the corresponding homopolymers. The analytical investigation of fourteen copolymers made of methyl-methacrylate (MMA) or ethyl-methacrylate (EMA) as the basis monomer is summarized. Their polymerization behaviors are examined by NMR spectroscopy with subsequent copolymerization parameter evaluation according to Fineman-Ross and Kelen-Tüdös. Therefore, some r-parameter sets are shown to be capable of copolymerizations with very high conversions. The first applications as high-temperature resistant (HT) materials for HT-POFs are presented. Copolymers containing isobornyl-methacrylate (IBMA) as the comonomer are well-suited for this demanding application