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Synthesis and characterization of the thermal and the solvatochromic properties...
Raposo, M. Manuela M.; Ferreira, Ana M. P. F.; Amaro, Mariana; Belsley, M.; Moura, João C. V. P.A series of heterocyclic azo dyes was synthesized by diazotation of several substituted anilines and coupling with 5-N,N-dialkylamino-2,2´-bithiophenes to give 4-phenylazo-5-N,N-dialkylamino-2,2´-bithiophenes 4-7. This reaction contrasts with the behavior of 5-alkoxy-2,2´-bithiophenes towards aryldiazonium salts which gave 5-phenylazo-5-alkoxy-2,2´-bithiophenes. The thermal stability of the derivatives was eval...
Novel photochromic 2,2´-bithiophene azo dyes
Coelho, Paulo J.; Carvalho, Luís H. Melo de; Moura, João C. V. P.; Raposo, M. Manuela M.The photochromic behaviour of two series of 2,2’-bithiophene azo dyes in THF solutions was studied. The photochromic properties and colour constancy were strongly dependent on the substitution pattern of the dyes. Under visible irradiation (> 420 nm) while some dyes exhibited a significant change in the colour intensity others exhibited an almost stable absorption. The photokinetic parameters of these systems a...
5-Arylazo-2,2´-bithiophenes : a novel promising series of NLO chromophores
Raposo, M. Manuela M.; Ferreira, Ana M. P. F.; Belsley, M.; Gomes, E. Matos; Moura, João C. V. P.The synthesis of 5-arylazo- substituted bithiophenes and their UV-visible, solvatochromic and nonlinear optical properties (NLO) are described. In agreement with the solvatochromic data and also with the second-order molecular NLO characterization, the new donor-acceptor systems could find application as suitable solvatochromic probes and also as new NLO materials.
5´-alkoxy-2,2´-bithiophene azo dyes : a novel promising series of NLO chromophores
Raposo, M. Manuela M.; Ferreira, Ana M. P. F.; Belsley, M.; Moura, João C. V. P.A series of bithienyl azo dyes has been prepared from their corresponding coupling components, 5-alkoxy-2,2´-bithiophenes. The solvatochromic behavior of the compounds was investigated. The hyperpolarizabilities β of derivatives 3-5 were measured using hyper-Rayleigh scattering and thermogravimetric analysis (TGA) was used to evaluate their thermal stability. The experimental results indicate that, good nonlin...
Synthesis and fluorescence properties of side-chain carboxylated 5,9-diaminoben...
Frade, Vânia H. J.; Gonçalves, M. Sameiro T.; Moura, João C. V. P.The efficient synthesis of a series of novel side-chain carboxylated 5,9-diaminobenzo[a]phenoxazinium salts is described. The ring system was prepared by the reaction of 5-alkylamino-2-nitrosophenol hydrochlorides with the appropriate N-alkylated-naphthylamine. Evaluation of the visible and fluorescence properties of the cationic dyes was carried out in ethanol and water at physiological pH. In both solvents th...
Chromophoric azo reagents for amino acid and peptide labeling
Fraga, Susana M. B.; Gonçalves, M. Sameiro T.; Moura, João C. V. P.; Rani, KavithaFour carboxylic azo dyes are presented as new markers with spectroscopic absorption peaks ranging from 400 to 500 nm for amino acid and peptide labeling at their N-terminus. Labeling can also be performed at side chain residues as it is exemplified with lysine and serine.
Reaction of carboxylic dyes with wool and polyamide : part. III : effect of the...
Gomes, Jaime Rocha; Gonçalves, M. Sameiro T.; Campos, Ana M. F. Oliveira; Moura, João C. V. P.; Maia, Hernâni L. S.; Hrdina, RadimDyes containing a carboxylic acid group had been shown to react with wool and polyamide fibres when activated with ethyl chloroformate (Parts I and II). One of the dyes, 3-aminobenzoic acid →N,N-dimethylaniline, was, in this work, activated with other chlorofirmates, so as to improve the dyeing conditions. Benzyl chloroformate was found to be a good substitute since it is not as volatile as ethyl chloroformate,...
A novel carboxy-dye reactive system of potential applicability to Wool and Nylo...
Gomes, Jaime Rocha; Moura, João C. V. P.; Campos, Ana M. F. Oliveira; Maia, Hernâni L. S.Dyes containing carboxylic acid groups have the potential to be reacted with the amino groups of wool and nylon fibres by prior activation with ethyl chloroformate (forming a mixed anhydride). The scope of this reaction has been examined in solution using a range of carboxy dyes with cyclohexyl-amine or lysine as model amine substrates. The expected amides are formed in good yields, and have been isolated and c...
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