Sousa, MM, Melo MJ, Parola AJ, de Melo JSS, Catarino F, Pina F, Cook FEM, Simmonds MSJ, Lopes JA.
2008.
Flavylium chromophores as species markers for dragon's blood resins from Dracaena and Daemonorops trees, 2008. Journal of Chromatography A. 1209:153-161.
AbstractA simple and rapid liquid chromatographic method with diode-array UV-vis spectrophotometric detection has been developed for the authentication of dragon's blood resins from Dracaena and Daemonorops trees. Using this method it was discovered that the flavylium chromophores, which contribute to the red colour of these resins, differ among the species and could be used as markers to differentiate among species. A study of parameters, such as time of extraction, proportion of MeOH and pH, was undertaken to optimise the extraction of the flavyliums. This method was then used to make extracts from samples of dragon's blood resin obtained from material of known provenance. From the samples analysed 7,6-dihydroxy-5-methoxyflavylium (dracorhodin), 7,4'-dihydroxy-5-methoxyflavylium (dracoflavylium) and 7,4'-dihydroxyflavylium were selected as species markers for Daemonorops spp., Dracaena draco and Dracaena cinnabari, respectively. The chromatograms from these samples were used to build an HPLC-DAD database. The ability to discriminate among species of dragon's blood using the single marker compounds was compared with a principal components analysis of the chromatograms in the HPLC-DAD database. The results from the HPLC-DAD method based on the presence of these flavylium markers was unequivocal. The HPLC-DAD method was subsequently applied to 37 samples of dragon blood resins from the historical samples in the Economic Botany Collection, Royal Botanic Gardens, Kew. The method identified anomalies in how samples in this collection had been labelled. It is clear that the method can be used to evaluate the provenance of samples used in different areas of cultural heritage. It also could be used to monitor the trade of endangered species of dragon's blood and the species being used in complex formulations of traditional Chinese medicine. (C) 2008 Elsevier B.V. All rights reserved.
Vidinha, P, Lourenco NMT, Pinheiro C, Bras AR, Carvalho T, Santos-Silva T, Mukhopadhyay A, Romao MJ, Parola J, Dionisio M, Cabral JMS, Afonso CAM, Barreiros S.
2008.
Ion jelly: a tailor-made conducting material for smart electrochemical devices, 2008. Chemical Communications. :5842-5844.
AbstractWe present a new concept for the design of a polymeric conducting material that combines the chemical versatility of an organic salt ( ionic liquid) with the morphological versatility of a biopolymer ( gelatin); the resulting 'ion jelly' can be applied in electrochemical devices, such as batteries, fuel cells, electrochromic windows or photovoltaic cells.
Sousa, MM, Miguel C, Rodrigues I, Parola AJ, Pina F, de Melo JSS, Melo MJ.
2008.
A photochemical study on the blue dye indigo: from solution to ancient Andean textiles, 2008. Photochemical & Photobiological Sciences. 7:1353-1359.
AbstractThe degradation of indigo and its water soluble derivative indigo carmine was investigated under light excitation in the presence and absence of molecular oxygen in solution (homogeneous) and gels (heterogeneous) media. Collagen and carboxymethylcellulose (CMC) aqueous gels were chosen to simulate a natural textile environment, wool and cotton, respectively. Isatin was found to be the major degradation product of indigo. In solution, the photodegradation quantum yields (Phi(R)) were in the order of 10(-4), with the exception of aqueous media (Phi(R) = 9 x 10(-6)), and dependent on the irradiation wavelength. In the case of indigo carmine the Phi(R) values were found to suffer a 2-fold increase upon going from water to gels. The results indicate the absence of degradation products involving singlet oxygen and suggest peroxides, or other oxygen based radicals, to have a key role in the degradation of indigo. Finally, the relevance of the simulation is discussed by comparing the main degradation products to those found in the blues of millenary Andean textiles.
Sousa, MM, Melo MJ, Parola AJ, Morris PJT, Rzepa HS, de Melo JSS.
2008.
A Study in Mauve: Unveiling Perkin's Dye in Historic Samples, 2008. Chemistry-a European Journal. 14:8507-8513.
AbstractThe analysis of different historic mauve samples-mauve salts and dyed textiles-was undertaken to establish the exact nature of the iconic dye produced by W.H. Perkin in the nineteenth century. Fourteen samples from important museum collections were analyzed, and it was determined that. in contrast to the general wisdom that mauveine consists of C, and C, structures. Perkin's mauveine is a complex mixture of at least thirteen methyl derivatives (C, to C(28)) with a 7-amino5-phenyl-3-(phenylamino)phenazin-5- ium core. A fingerprint was established in which mauveines A or B were dominant, and in which mauveines B2 and C(25) were found to be important tracers to probe the original synthesis. Counterion analysis showed that all the mauve salts should be dated after 1862. Perkin's original recipe could be identified in three textile samples, and in these cases, mauveines A and C25 were found to he the major chromophores. These are now shown to be the samples containing the "original mauve".
Rodriguez, L, Lima JC, Parola JA, Pina F, Meitz R, Aucejo R, Garcia-Espana E, Llinares JM, Soriano C, Alarcon J.
2008.
Anion detection by fluorescent Zn(II) complexes of functionalized polyamine ligands. Inorganic Chemistry. 47:6173-6183., Number 14
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Sousa, MM, Melo MJ, Parola JA, Seixas de Melo SJ, Catarino F, Pina F, Cook FEM, Simmonds MSJ, Lopes JA.
2008.
Flavylium chromophores as species markers for dragon's blood resins from Dracaena and Daemonorops trees. Journal of Chromatography A. 1209:153-161., Number 1-2
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