Supported ruthenium catalysts in hydrodechlorination of CCl2F2 (CFC-12)

Active carbon-and MgF₂-supported ruthenium catalysts characterized by a comparable metal dispersion were investigated in CCl₂F₂ hydrodechlorination. Ruthenium, especially when supported on carbon, exhibits a considerable selectivity to CHClF₂. This propensity and a noticeable activity towards C₂-products differentiate ruthenium from palladium catalysts. Dedicated to Professor Pál Tétényi on the occasion of his 70th birthday     

Antimicrobial Activity of Gemini Surfactants with Ether Group in the Spacer Part

Due to their large possibility of the structure modification, alkylammonium gemini surfactants are a rapidly growing class of compounds. They exhibit significant surface, aggregation and antimicrobial properties. Due to the fact that, in order to achieve the desired utility effect, the minimal concentration of compounds are used, they are in line with the principle of greenolution (green evolution) in chemistry. In this study, we present innovative synthesis of the homologous series of gemini surfactants modified at the spacer by the ether group, i.e., 3-oxa-1,5-pentane-bis(N-alkyl-N,N-dimethylammonium bromides). The critical micelle concentrations were determined. The minimal inhibitory concentrations of the synthesized compounds were determined against bacteria Escherichia coli ATCC 10536 and Staphylococcus aureus ATCC 6538; yeast Candida albicans ATCC 10231; and molds Aspergillus niger ATCC 16401 and Penicillium chrysogenum ATCC 60739. We also investigated the relationship between antimicrobial activity and alkyl chain length or the nature of the spacer. The obtained results indicate that the synthesized compounds are effective microbicides with a broad spectrum of biocidal activity.     

Going beyond the borders: pyrrolo[3,2-b]pyrroles with deep red emission

A two-step route to strongly absorbing and efficiently orange to deep red fluorescent, doubly B/N-doped, ladder-type pyrrolo[3,2-b]pyrroles has been developed. We synthesize and study a series of derivatives of these four-coordinate boron-containing, nominally quadrupolar materials, which mostly exhibit one-photon absorption in the 500–600 nm range with the peak molar extinction coefficients reaching 150 000, and emission in the 520–670 nm range with the fluorescence quantum yields reaching 0.90. Within the family of these ultrastable dyes even small structural changes lead to significant variations of the photophysical properties, in some cases attributed to reversal of energy ordering of alternate-parity excited electronic states. Effective preservation of ground-state inversion symmetry was evidenced by very weak two-photon absorption (2PA) at excitation wavelengths corresponding to the lowest-energy, strongly one-photon allowed purely electronic transition. π-Expanded derivatives and those possessing electron-donating groups showed the most red-shifted absorption- and emission spectra, while displaying remarkably high peak 2PA cross-section (σ_2PA) values reaching ∼2400 GM at around 760 nm, corresponding to a two-photon allowed higher-energy excited state. At the same time, derivatives lacking π-expansion were found to have a relatively weak 2PA peak centered at ca. 800–900 nm with the maximum σ_2PA ∼50–250 GM. Our findings are augmented by theoretical calculations performed using TD-DFT method, which reproduce the main experimental trends, including the 2PA, in a nearly quantitative manner. Electrochemical studies revealed that the HOMO of the new dyes is located at ca. −5.35 eV making them relatively electron rich in spite of the presence of two B⁻–N⁺ dative bonds. These dyes undergo a fully reversible first oxidation, located on the diphenylpyrrolo[3,2-b]pyrrole core, directly to the di(radical cation) stage.

Ladder-type heterocycles encompassing two B⁻–N⁺ dative bonds possess intense green to red emission, large 2PA cross-sections and superb photostability.     

Kinetics of refractive index changes in polymeric photochromic films

Methacrylate copolymers containing, in side chain azobenzene groupings with heterocyclic sulfonamide substituents: N-(2,6-dimethylpyrimidin-4-yl)sulfamoyl (sulfisomidine) and N-(5-methylisoxazol-3-yl) sulfamoyl (sulfamethoxazole) were investigated. The materials undergo reversible trans-cis isomerisation during illumination with light. This results in changes of dipole moment, polarizability and refractive index. Ellipsometric measurements showed a distinct decreasing refractive index during illumination with light corresponding to absorption band (ca. 450 nm). Depending on the polymer, the change of real part of refractive index in spin-coated films was between 0.016 and 0.031. The dynamics of growth and decay of refractive index changes, was described by biexponential function approach.     

Bispalladium(II) Complexes of di-p-Pyrirubyrin Derivatives as Promising Near-Infrared Photoacoustic Dyes

The insertion of palladium(II) into di-p-pyrirubyrin results in mutually convertible bimetallic complexes. Post-synthetic functionalization of one of them yielded bispalladium(II) dioxo-di-p-pyrirubyrin and, after demetallation, dioxo-di-p-pyrirubyrin, introducing for the first time the α,β′-pyridin-2-one unit into the macrocyclic frame. Bispalladium(II) di-p-pyrirubyrin 6 , bispalladium(II) dioxo-di-p-pyrirubyrin 9 , and dioxo-di-p-pyrirubyrin 10 absorb and emit light around 1000 nm and are characterized by high photostability. Thus, they are promising candidates for near-infrared photoacoustic dyes, ideally targeting ( 9 ) the wavelength of Yb-based fiber lasers. The incorporation of an α,β′-pyridine moiety into expanded porphyrins opens a highly interesting area of research due to the attractive optical and coordination properties of the resulting molecules.