Dyes ions have a tendency to self-associate in aqueous solutions. Since almost all textile dyes are applied from aqueous systems, it is important to understand the association of dyes in water, and to determine the number of chemical species presented in the system. The main factors influencing aggregation are dye concentration, electrolyte concentration, and temperature. In the present work, the influence of the coupling component structure on the dye aggregation is presented. The molecular aggregation has been studied spectrophotometrically in aqueous solutions as a function of dye concentration (10^-6 ¸ 10^-3 mol/L). As the concentration increases, different changes were observed in the dyes UV-vis spectra indicating that the molecules are beginning to aggregate. The shapes of the obtained spectra were totally different as the coupling component structure was changed in the dye molecule.From the matriceal analysis, the number of chemical species presented in the system (in domain of concentrations studied) was determined. The mathematical calculations confirm the experimental data regarding the aggregation of the investigated dyes.

Two new symmetrical disazo direct dyes containing 4,4\'-diaminostilbene-2,2\'disulphonic acid as middle component and 3-bromosalicylanilide and 4-bromosalicylanilide as coupling components were synthesized. The dyes were characterised by TLC, VIS, FT/IR, ¹³C-NMR spectroscopy, and HPLC technique. The colour, spectrophotometric study of the two disazo stilbene dyes with symmetrical structure was performed using the CIE 1976 (CIELAB) uniform colur space parameters, under the CIE (Commission Internationale d\'Eclairage) recommended illuminants: D65 (natural day light), A (tungsten light), F2 (fluorescent light) and the standard 10° observer respectively. The colour differences (ΔEab*) and (ΔE_CMC) were calculated against one standard, revealing a high colouring power for the two new studied dyes.

The use of fluorescent probes for detection of biological and organic molecules has increased in the last years due to their high sensitivity and ease of use compared to radiochemical methods. Interference with the measurement of the label fluorescence could occur in many biological samples, which display some fluorescence of their own, usually in the blue or green region of the spectrum. Consequently, in studies with biomolecules it is desirable to improve the sensitivity of detection using dyes with absorption and fluorescence in the red or near infrared spectral region. Therefore, in these spectral regions it is possible the use of inexpensive and effective excitation sources, e.g. laser diodes.^1,2 Having these facts in mind and as a continuation of our previous research,³ fluorescent benzo[a]phenoxazinium chlorides possessing different substituents at position 2, namely propoxyl, 4-ethoxy-4-oxobutoxyl or 3-carboxypropoxyl groups, and at positions 5, 9 and 10 of the tetracyclic system, the amino, ethylamino and methyl groups, respectively, were synthesised. Absorption and emission studies of all compounds were also carried out in ethanol, water and at simulated physiological conditions (pH 7.4). Acknowledgements: Thanks are due to the Foundation for Science and Technology (Portugal) for its financial support of Centre of Chemistry. The NMR spectrometer Bruker Avance III 400 is part of the National NMR Network (RNRMN), and was purchased in the framework of the National Program for Scientific Re-equipment, contract REDE/1517/RMN/2005 with funds from POCI 2010 (FEDER) and FCT. References 1. Gonçalves, M.S.T. Chem. Rev. 2009, 109, 190. 2. Gonçalves, M.S.T. Optimized UV/Visible Fluorescent Markers in Advanced Fluorescence Reporters in Chemistry and Biology I. Fundamentals and Molecular Design, Demchenko A.P. (Volume Ed.), O.S. Wolfbeis (Series Ed.), Springer Series on Fluorescence, Vol. 8, Ch. 2, 27-64, Springer, Heidelberg, Germany, 2010. 3. a) Alves, C.M.A. et al Tetrahedron Lett. 2011, 52, 112. b) Naik, S. et al Eur. J. Org. Chem. 2011, 2491.

Several research studies involving fused heteroaromatic dyes based on the oxazine moiety have been focused on their absorption and fluorescence spectroscopic properties.¹ These long-wavelength fluorophores find applications as biological probes, namely in covalent labeling of amino acids, proteins, peptides and DNA.² Also, more frequently they have been used in non-covalent labeling, such as staining nucleic acids in a variety of context, monitoring protein conformation alterations or for therapeutic purposes.³ Although the interest of photophysical properties, several compounds possessing the phenoxazine nucleus have been stressed due to their antiproliferative properties with potential applications both as antitumour and as antimicrobial agents. Considering our promising previous results in this field,⁴ and having in mind future evaluation of biological activity, we decided to synthesise new benzo[a]phenoxazinium salts having chlorinated terminals at their substituents in 2- and 9- positions. Furthermore, these compounds can also be used as covalent and non-covalent probes, and consequently the photophysical properties were also studied in ethanol and water in simulated physiological conditions. Acknowledgements: Thanks are due to the Foundation for Science and Technology (Portugal) for its financial support of Centre of Chemistry. The NMR spectrometer Bruker Avance III 400 is part of the National NMR Network (RNRMN) and was purchased in the framework of the National Program for Scientific Re-equipment, contract REDE/1517/RMN/2005 with funds from POCI 2010 (FEDER) and FCT. References 1. Jose, J.; Burgess, K. Tetrahedron 2006, 62, 11021-11037. 2. Salomi, B. S. B.; Mitra, C. K.; Gorton, L. Synth. Met. 2005, 155, 426-429. 3. Nakanishi, J.; Nakajima, T.; Sato, M.; Ozawa, T.; Tohda, K.; Umezawa, Y. Anal. Chem. 2001, 73, 2920-2928. 4. Frade, V. H. J.; Sousa, M. J.; Moura, J. C. V. P.; Gonçalves, M. S. T. Bioorg. Med. Chem. 2008, 16, 3274-3282.

In this work we studied changes in poly(vinyl alcohol) (PVA) conformations with respect to the polymer concentrations, using Langevin dynamics at 300 ± 10 K. Constructed polymer chain consisted of 90 units and the friction coefficient of the solvent (water) was set to 55 ps^-1. We also turned to quantum mechanical calculations, using B3LYP/6-31+G* level of theory in order to investigate the association via hydrogen bonds (HB) between two OH-groups of PVA and between OH-group and water. It was demonstrated that in dilute solutions PVA macromolecules tend to shrink and form more dense coils by comparison with polymers in more concentrated solutions, where two or more chains overlap, entangle and associate via intermolecular hydrogen bonding. We also established that HB between OH-groups and water molecules are less stable than those between two not adjacent OH-groups of one or various chains. The obtained data allow us to consider that in the case of low PVA concentrations, the distances between parts of one chain tend to decrease that leads to the polymer conformation favorable for the intramolecular cross-linking when the acetalization reaction of PVA takes place. As far as the cross-linking occurs within the coil, the resulting product should loss it flexibility. We assumed that the mass-transfer in this system should be slower than the subsequent chemical reaction, so the acetalization of partially modified PVA should proceed with essential retardation.

Corannulene is an unsaturated hydrocarbon composed of fused rings, one central five-membered ring and five peripheral six-membered rings. Its structure can be considered as a portion of C₆₀. Corannulene is a curved pi surface, but unlike C₆₀, it has two completely different faces: one concave (inside) and one convex (outside). In this work, computational modeling of the binding between alkali metals cations and corannulene has been performed at the DFT and MP2 levels. Different isomers of the corannulene/M⁺ binding have been studied and the transition states interconnecting local minima were located. The alkali cations can be bound to five or six membered ring in both faces. In DFT calculations, the binding to the convex face (outside) is favored relative to the concave face for the three alkali cations as it already has been published [R.C. Dunbar, J. Phys. Chem. A 2002, 106, 9809]. For Li⁺ and Na⁺, MP2 calculations are very similar and show the same trend, but for K⁺ the calculations are quite different and the trend is reversed. According to our results, migration of cations can take place over the convex or the concave pi-face. There are two ways to transform a concave complex in a convex complex: migration across the edge of corannulene and bowl-to-bowl inversion.

Novel mulriple polymer polyaniline/Bi₂SnTiO₇ was synthesized by chemical oxidation in-situ polymerization method and sol-gel method for the first time. The structural and photocatalytic properties of novel polyaniline/Bi₂SnTiO₇ have been characterized by X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy and X-ray spectrometry. The photocatalytic degradation of methylene blue was realized under visible light irradiation with novel polyaniline/Bi₂SnTiO₇ as catalyst. The results showed that novel polyaniline/Bi₂SnTiO₇ owned higher catalytic activity compared with Bi₂SnTiO₇ or pure TiO₂ or N-doped TiO₂ for photocatalytic degradation of methylene blue under visible light irradiation. The photocatalytic degradation of methylene blue with novel polyaniline/Bi₂SnTiO₇ or N-doped TiO₂ as catalyst followed the first-order reaction kinetics, and the first-order rate constant was 0.01350 or 0.00333 min-1. After visible light irradiation for 220 min with novel polyaniline/Bi₂SnTiO₇ as catalyst, complete removal and mineralization of methylene blue was observed. The reduction of the total organic carbon, the formation of inorganic products, SO₄^2- and NO₃^-, and the evolution of CO₂ revealed the continuous mineralization of methylene blue during the photocatalytic process. The possible photocatalytic degradation pathway of methylene blue was obtained under visible light irradiation. Novel mulriple polymer polyaniline/Bi₂SnTiO₇/(visible light) photocatalysis system was found to be suitable for textile industry wastewater treatment and could be used to solve other environmental chemical pollution problems.

Bacterial diseases of freshwater fish epithelia have been extensively studied; however in marine fishes relatively few bacterial skin and gill diseases have been characterized. Tenacibaculum maritimum, a Gram-negative and filamentous bacterium, has been described as the etiological agent of tenacibaculosis in marine fish. Since 1990, as the farming of fish became a steadily growing industry, this disease has been widely distributed in several countries and is considered a limiting factor for the culture of many species of commercial value in the world. Among the drugs used in the past few years enrofloxacin proved to be the most useful compound in the control of tenacibaculosis outbreaks, although the rapid appearance of resistant strains has already been described. Therefore, it is important to discover new classes of selective antimicrobial drugs. Coumarin derivatives are a class of compounds that present a wide range of pharmacological activities. Among others, recent studies pay special attention to the antibiotic properties of the coumarin moiety. In order to contribute to the development of new agents, in the present communication we have synthesized new 3-arylcoumarin derivatives, structurally related with well know antibiotic novobiocin. On this scaffold we introduced substituents with different electronic, steric and/or lipophilic properties in different positions of the aromatic rings. The compounds have been prepared via a palladium-catalyzed coupling type Suzuki reaction of phenyliodonium zwitterion species previously synthesized by us. Further, were evaluated for antibacterial activity against bacterial and fungal strains. The preliminary results of biological activity and/or selectivity against Tenacibaculum Maritimum will be presented.

Aliphatic polyesters are one of the classes of materials that can potentially meet the varying requirements put for tissue scaffolds. In recent years, much attention was paid to design biocompatible scaffolds for tissues that would have the similarity to natural tissues in terms of stiffness, flexibility and endurance. Polyesters of citric acid and diols are promising materials for tissue scaffolds. They are characterized by simplicity of synthesis, use of low-cost and non-toxic monomers as well as ease of controlling properties of obtained products by polymerization process operating conditions. Many attempts at modification of polyesters based on citric acid with natural polyols such as xylitol and mannitol have been observed in recent years. Synthetic polyesters can also be modified with vegetable oil-based polyols being diverse in terms of hydroxyl number and functionality, which leads to change of mechanical properties of obtained polyesters. In this work, the effect of rapeseed oil-based polyols addition on the properties of citric acid-based polyesters has been investigated. It has been found that modification with polyols leads to improvement of tensile strength of obtained materials and additionally in reduction of elongation at break values. However, the modification had no significant influence on swelling properties of achieved polyesters.

The extraordinary structures and properties of fullerenes have had an important impact on nanotechnology as these compounds exhibit outstanding mechanical and electronic properties. 1,3-Dipolar cycloadditions (1,3-DCs) have proved to be a powerful way to functionalize these conjugated ? systems and have offered wide opportunities for the creation of new nanocarbon structures with potential application in biological, biotechnology, material science and medicinal chemistry. The 1,3-DCs of fullerene (C60) with nitrile oxides, RCNO, have been studied in the gas phase using density functional theory (DFT) at the B3LYP/6-31G(d) level. Energetic and kinetic parameters have been determined at room temperature so as to investigate the effect of electron-withdrawing (R = F, Cl, Br, NC, CN and NO2) and electron-releasing (R = Me and Et) substituents attached to the nitrile oxides on the 1,3-DCs. These parameters have been interpreted in terms of group electronegativity and DFT reactivity indices. An unexpected behaviour was observed for the 1,3-DC involving FCNO as these reactions have some pseudodiradical character. Inspired by the results of the 1,3-DCs of nitrile oxides to C60, we have extended this theoretical gas phase research to the addition of a second HCNO to the cycloadduct of the addition of HCNO on C60. The various possibilities for the second addition are being explored with the aim of determining the thermodynamic and kinetic products. The findings of our research should be helpful to experimentalists in their quests for functionalized fullerenes.