Synthesis of novel azo compounds containing 5(4H)-oxazolone ring as potent tyrosinase inhibitors

Six new azo dyes containing of 5(4H)-oxazolone ring were prepared by diazotization of 4-aminohippuric acid and coupling with N,N-dimethylaniline, 1-naphthol and 2-naphthol and condensation with 4-fluoro benzaldehyde or 4-trifluoromethoxy benzaldehyde. The new compounds were fully characterized by spectroscopic techniques. All synthesized compounds exhibited high tyrosinase inhibitory behavior. The results of mushroom tyrosinase inhibition assays indicate that the 4-trifluoromethoxy derivatives have high degrees of inhibition and N,N-dimethylaniline derivatives are better for tyrosinase inhibition than 1-naphthol and 2-naphthol derivatives. All synthesized azo compounds (4a-4f) showed the most potent mushroom tyrosinase inhibition, comparable to that of Kojic acid and l-mimosine, as reference standard inhibitors. © 2013 Elsevier Ltd. All rights reserved

Synthesis and Spectroscopic Study of Naphtholic and Phenolic Azo Dyes

Azo dyes are extremely important in variety of industries for variety of technical purposes. Hence, a series of naphtholic azo dyes 1-9 were synthesized via diazotization of substituted aniline derivatives followed by azo coupling with 2-naphthol. In similar manner, diazotization followed by azo coupling with phenol afforded phenolic azo dyes 10-17 in excellent yields. The chemical structures of all synthesized compounds were confirmed using analytical data and spectroscopic technique which include Uv-visible, IR, Mass spectra, 1H- and 13C-NMR

Epsilon-Near-Zero Al-Doped ZnO for Ultrafast Switching at Telecom Wavelengths: Outpacing the Traditional Amplitude-Bandwidth Trade-Off

Transparent conducting oxides have recently gained great attention as CMOS-compatible materials for applications in nanophotonics due to their low optical loss, metal-like behavior, versatile/tailorable optical properties, and established fabrication procedures. In particular, aluminum doped zinc oxide (AZO) is very attractive because its dielectric permittivity can be engineered over a broad range in the near infrared and infrared. However, despite all these beneficial features, the slow (> 100 ps) electron-hole recombination time typical of these compounds still represents a fundamental limitation impeding ultrafast optical modulation. Here we report the first epsilon-near-zero AZO thin films which simultaneously exhibit ultra-fast carrier dynamics (excitation and recombination time below 1 ps) and an outstanding reflectance modulation up to 40% for very low pump fluence levels (< 4 mJ/cm2) at the telecom wavelength of 1.3 {\mu}m. The unique properties of the demonstrated AZO thin films are the result of a low temperature fabrication procedure promoting oxygen vacancies and an ultra-high carrier concentration. As a proof-of-concept, an all-optical AZO-based plasmonic modulator achieving 3 dB modulation in 7.5 {\mu}m and operating at THz frequencies is numerically demonstrated. Our results overcome the traditional "modulation depth vs. speed" trade-off by at least an order of magnitude, placing AZO among the most promising compounds for tunable/switchable nanophotonics.Comment: 14 pages, 9 figures, 1 tabl

Preparation and characterization of bis-[1,3,5]triazinyl diazenes and their utilization as flame retardants in polypropylene films

A series of bis-[1,3,5]triazinyl diazenes and two metal complexes thereof were synthesized and tested as new flame retardants in polypropylene films. It was observed that electron withdrawing triazinyl ring substituents (i.e. Cl and phenyl moieties) improved the thermal stability of diazene compounds, whereas electron donating groups (i.e. methoxy, dimethylamino and ethylthio moieties) had a destabilizing effect. TGA, DTA/DSC, NMR and ATR-FTIR were used for the characterization. Quantum mechanical modeling (Gaussian 09) was also utilized to facilitate the interpretation of the NMR data. Bis-(4,6-dichloro-[1,3,5]triazin-2-yl)-diazene 1 and bis-(4,6-dimethoxy-[1,3,5]triazin-2-yl)-diazene 2 were found to be effective flame retardants in polypropylene films and DIN4102-1 B2 classification was reached already at a loading of 0.5 wt%. Interestingly, the copper complex of 2 showed even higher fire retardant activity than its precursor 2, whereas the corresponding zinc complex exhibited lower flame retardant efficacy than its precursor

Annual Report on the Activities funded by the Seventh, Eighth and Ninth European Development Funds (EDFS)(2008/C 286/02). OJ 273, 10.11.2008.

U sklopu ovog rada provedena je sinteza, karakterizacija i konformacijska analiza novih derivata aromatskih trinitrozo i azo spojeva. Aromatski trinitrozo spoj pripravljen je reakcijom redukcije iz odgovarajućeg trinitro spoja te su IR spektroskopijom proučene fototermičke reakcije polimernog oblika u čvrstom stanju pri kriogenim uvjetima. Kinetika polimerizacije monomernog oblika trinitrozo spoja u čvrstom stanju, pripravljenog kriogenom fotodisocijacijom polimera, praćena je vremenski razlučenom IR spektroskopijom. Aromatski azo spojevi priređeni su Millsovom reakcijom između aromatskog trinitrozo spoja i aromatskih diamino spojeva te aromatskog triamino spoja i aromatskih dinitrozo spojeva. Pripravljeni spojevi karakterizirani su IR spektroskopijom te difrakcijom rentgenskih zraka na praškastom uzorku. Dobiveni produkti proučavani su metodama računalne kemije. Na modelnim spojevima s azodioksidnom i azo vezom odabrane su molekularno i kvantno-mehaničke metode koje dobro reproduciraju njihove eksperimentalno određene geometrije. Provedena je pretraga konformacijskog prostora pretpostavljenih modela novosintetiziranih spojeva kojom su analizirane njihove optimizirane geometrije. Dane su smjernice za daljnji dizajn sličnih spojeva.Synthesis, characterization and conformational analysis of new derivatives of aromatic trinitroso and azo compounds was performed. Aromatic trinitroso compound was prepared by reduction of trinitro derivative, and solid-state cryogenic photothermal reactions of polymeric form were studied by IR spectroscopy. Kinetics of solid-state polymerization of monomeric trinitroso compound, produced by cryogenic photodissociation of polymer, was monitored by time-resolved IR spectroscopy. Aromatic azo compounds were synthesized by Mills reaction between aromatic trinitroso compound and aromatic diamino derivatives, and aromatic triamino compound and aromatic dinitroso derivatives. Compounds were characterized by IR spectroscopy and powder X-ray diffraction. The products were investigated by computational chemistry methods. Models with azodioxide and azo bonds were used to find molecular and quantum-mechanical methods enabling reproduction of the experimentally determined geometries. Conformational space search of the assumed models of new compounds was performed and the obtained geometries were analyzed. Guidelines for future design of similar compounds were provided

Enzymatic degradation of azo dyes under long time oxidative conditions

Trametes villosa laccase was used for direct azo dye degradation for which the reaction products were analyzed over long periods of time. Laccases have been extensively studied for the degradation of azo dyes [1-3].These enzymes are multicopper phenol oxidases that decolorize azo dyes through a highly non-specific free radical mechanism forming phenolic type compounds, thereby avoiding the formation of toxic aromatic amines [4,5].In the literature, there are a large number of papers reporting on decolorization of azo dyes however the fate of the products of azo dye laccase reactions is ignored [6-8]. Therefore, the purpose of this work is the study of the azo dye degradation products in the presence of laccase. Direct azo dye laccase degradation and amino-phenols polymerization was performed for several days. The formed soluble products were studied by LC-MS while the polymerized insoluble products were studied by 13C -NMR. LC-MS analysis shows the formation of phenolic compounds in the dye oxidation process as well as a large amount of polymerized products that retain the azo group integrity. The amino-phenols reactions were also investigated by 13C-NMR and LC-MS analysis and the real polymerization character of laccase enzymes was shown. This study highlights the fact that laccases polymerize the reaction products obtained in long time batch decolorization processes of the azo dyes. These polymerized products provide unacceptable color levels in effluents limiting the application of laccases as bioremediation agents

Supramolecular hierarchy among halogen and hydrogen bond donors in light-induced surface patterning

Halogen bonding, a noncovalent interaction possessing several unique features compared to the more familiar hydrogen bonding, is emerging as a powerful tool in functional materials design. Herein, we unambiguously show that one of these characteristic features, namely high directionality, renders halogen bonding the interaction of choice when developing azobenzene-containing supramolecular polymers for light-induced surface patterning. The study is conducted by using an extensive library of azobenzene molecules that differ only in terms of the bond-donor unit. We introduce a new tetrafluorophenol-containing azobenzene photoswitch capable of forming strong hydrogen bonds, and show that an iodoethynyl-containing azobenzene comes out on top of the supramolecular hierarchy to provide unprecedented photoinduced surface patterning efficiency. Specifically, the iodoethynyl motif seems highly promising in future development of polymeric optical and photoactive materials driven by halogen bonding

Using Box–Behnken experimental design to optimize the degradation of Basic Blue 41 dye by Fenton reaction

Degradation of a Basic Blue 41 dye using Fenton reagent was examined at laboratory scale in batch experiments using Box-Behnken statistical experiment design. Dyestuff, hydrogen peroxide (H2O2) and ferrous ion (Fe2+) concentrations were selected as independent factors. On the other hand, color and chemical oxygen demand (COD) removal were considered as the response functions. The value of coefficient of determination (R-2) for both color and chemical oxygen demand removal with values 0.98 and 0.99 shows the best agreement between predicted value and experimental values. Perturbation plots indicated that iron dosage has the most effect on both color and COD removal. Normalized plot of residuals also indicated that the models were adequate to predict for both responses. Color and COD removal increased with increasing H2O2 and Fe2+ concentrations up to a certain level. High concentrations of H2O2 and Fe2+ did not result in better removal of color and COD due to hydroxyl radical being gradually consumed by both oxidant and catalyst. Percent color removal was higher than COD removal indicating the production of colorless compounds. The second-order polynomial model revealed optimal process factor ratio. The ratio of H2O2/Fe2+/dyestuff which gives a complete color removal and 95% COD removal was found to be 1195 mg/L/90 mg/L/255 mg/L

Application of mechanically alloyed Mn-Al metallic particles to wastewater treatment: a comparative investigation of chemical and bacterial approaches to dye degradation in residual textile waters

Peer ReviewedPostprint (author's final draft

7-Azabicyclo[2.2.1]heptane N-Imide as an Intermediate in the Thermal Decomposition of N-Amino-7-Azabicyclo[2.2.1]heptane and the Corresponding Benzenesulphonamide

An intermediate in the thermal decomposition of N-amino-7-azabicyclo[2.2.1]heptane and the corresponding benzenesulphonamide derivative, whose structure is consistent with the formulation 7-azabicyclo[2.2.1]heptane N-imide, affords on thermal fragmentation the hydrocarbon products hexa-1,5-diene, bicyclo[2.2.0]hexane, and cyclohexene and does not rearrange to the corresponding stable 2,3-diazabicyclo[2.2.2]oct-2-ene isomer