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A Reusable Eu3+ Complex for Naked-Eye Discrimination of Methanol from Ethanol with a Ratiometric Fluorimetric Equilibrium in Methanol/Ethanol Mixtures
Publication . Leal, João P.; Paz, Filipe A. Almeida; Mendes, Ricardo F.; Moreira, Tiago; Outis, Mani; Laia, César A. T.; Monteiro, Bernardo; Pereira, Cláudia C. L.; LAQV@REQUIMTE; DQ - Departamento de Química; Wiley-VCH Verlag Berlin
Immediate naked eye distinction of methanol from ethanol can be performed by simple dissolution, in each of these solvents, of either [Na][EuFOD4] (1) complex or in mixture of products from the reaction between [P6,6,6,14][Eu(FOD)4] and NaOPhMe3, referred as 2, ([P6,6,6,14]+ = trihexyltetradecylphosphonium cation, FOD– = 1,1,1,2,2,3,3-heptafluoro-7,7-dimethyloctane-4,6-dionate). Additionally, an easy, low-cost, efficient and fast spectrofluorimetric method for the detection and quantification of methanol in mixtures with ethanol is described. This method is based on the changes in the Eu3+ luminescence in the visible region due to the interaction of the [P6,6,6,14][Eu(FOD)4] complex with these alcohols. A limit of detection as low as 15 % (w/w) of methanol in mixtures of ethanol/methanol is discussed considering a linear calibration curve.
Roman copper metallurgy: the Conimbriga situlae handle attachments
Publication . Lopes, Filipa Mendes da Ponte; Araújo, Maria de Fátima; Silva, Rui; Correia, Virgílio
The Romans are probably the best-known civilization of the Ancient times in the Western world – from architecture to monumental statuary, from the monetary system to the military strategies and the development of mining on an industrial scale, among many other fields of knowledge, have been widely studied. This vast amount of knowledge has been built largely due to archaeological evidence, but also because of the existence of contemporary written sources. In the Iberian Peninsula context, Conimbriga arises as one of the most important Roman archaeological sites when looking at the quantity, quality and diversity of their heritage. Concerning the Cu-based metallurgical productions, little is known in contrast with other imperial territories. The purpose of this study is the investigation of copper alloys from situlae and their components – handles and attachments – from Conimbriga in order to establish eventual relationships between elemental composition, thermomechanical processes and typology.
Additionally, similar artefacts from Bracara Augusta and Corredores were also studied in order to verify eventual correlations with Conimbriga “productions”, and also, to identify the possibility of local productions versus the importing of artefacts by comparing the results with those obtained on similar artefacts recovered from other Roman sites with the aim of providing a better comprehension of the Roman copper-based metallurgy in the Iberian Peninsula. The archaeometallurgical study was performed using non-invasive and micro-analytical techniques, such as micro-energy dispersive X-ray fluorescence spectrometry, optical microscopy and scanning electron microscopy, in order to respect the ethical principles applied to the study of cultural heritage.
The main results showed that the Cu-based metallurgy of roman situlae, attachments and handles from the Portuguese territory reveals some conservatism by the singularity of the presence of leaded coppers in some of the attachments and handles in comparison to the italic productions dominated by the presence of significant levels of Sn. In opposition, it also showed the prevalence of the usage of contemporary Roman Cu-based alloys, such as the mixture of Cu with Sn and Zn with or without Pb, besides the consistent usage of leaded bronzes as it was observed in other Roman provinces, namely in Britannia. This particular metallurgical production from Conimbriga also evidences technological versus economic factors as the main vectors for the type of alloy chosen to produce the different type of artefacts and lastly the aesthetical reasons related to the golden colour appearance promoted by the presence of the more expensive alloying elements found in the Roman Cu-based alloys: Sn and Zn. The incursion through the joining processes led to some important results in the particular field of Roman soldering, pointing to the use of Sn or Sn-rich soft solder to join the attachments to the situla.
Treatment of paper biodeterioration by fungi: An NMR approach to the preservation of human history
Publication . Barrulas, Raquel Alexandra Valadares; Corvo, Marta
The main goal of this dissertation was to develop a new class of materials in order to provide an improved solution to clean fungal staining in paper. Initially a screening of favourable interactions between pigment model compounds and ionic liquids (ILs) was accessed through Nuclear Magnetic Resonance (NMR) protocol. The most promising IL moieties were incorporated into polymer matrices. The final products were tested against contaminated paper samples.
The NMR approach allowed profiling the molecular interactions prevailing between ILs with cations such as 1-butyl-3-methylimidazolium ([BMIM]+), 1-ethyl-3-methylimidazolium ([EMIM]+), 1-butyl-2,3-dimethylimidazolium ([BDMIM]+), 1-benzyl-3-methylimidazolium ([BZMIM]+); and anions such as chloride, trifluoromethanesulfonate ([OTf]-), dicyanamide ([DCA]-) and tricyanomethanide (TCN]-), and model compounds (naphthalene, L-DOPA, veratrole, alizarin and quinizarin) with identification of the structural features in the IL pair responsible for the preferential interactions. The ILs [EMIM][TCN], [EMIM][OTf] and [EMIM][DCA] exhibited better interaction abilities with stronger interactions – hydrophobic and π-π stacking interactions. The monomers with cations [ETVIM]+ and [BVIM]+ as well as with anions [DCA]-, [OTf]-, bromide and [NTf2]- were synthetized and polymerized afterwards, with very high yields. Hydrogels derived from polymeric ILs (PILs) and agarose and/or PVP were obtained. The efficacy of the hydrogels obtained was tested on contaminated paper samples with A. niger, C. cladosporioides, P. chrysogenum and F. oxysporum. The most promising results were obtained with hydrogels with poly([ETVIM][DCA]) and poly([BVIM][OTf]) against P. chrysogenum and A. niger, respectively.
The gourd-shaped vessel: a Portuguese product?
Publication . Coutinho, Inês; Medici, Teresa; Wiley, Robert Christopher; Alves, Luís C.; Gratuze, Bernard; Vilarigues, Márcia; DCR - Departamento de Conservação e Restauro; VICARTE - Vidro e Cerâmica para as Artes; Corning Museum of Glass
Several glass assemblages excavated in Portugal and dated to the 17th century include a shape, derived from the traditional dried gourd bottle, that is uncommon elsewhere in Europe. Ten gourd-shaped bottles were selected from two archaeological assemblages (the monasteries of Santa Clara-a-Velha in Coimbra and Sao Joao de Tarouca) to be studied and chemically characterized by p-PIXE and LA-ICP-MS. The bright colors were analyzed by UV-Vis reflectance spectroscopy to identify the metallic ions responsible for those colors, thus revealing potential insights into color intent. Considering the complexity of the shape, some reproductions were made, indicating that the original glassmakers exercised high levels of temperature control and fully understood the Venetian technique of half-molding. Very high contents of alumina were found in the glass, which may indicate that the gourds were produced in Portugal using local raw materials.
Impact on CO2/N2 and CO2/CH4 separation performance using Cu-BTC with supported ionic liquids-based mixed matrix membranes
Publication . Monteiro, Bernardo; Nabais, Ana R.; Casimiro, Maria H.; Martins, Ana P. S.; Francisco, Rute O.; Neves, Luísa A.; Pereira, Cláudia C. L.; LAQV@REQUIMTE; DQ - Departamento de Química; MDPI AG
The efficient separation of gases has industrial, economic, and environmental importance. Here, we report the improvement in gas separation performance of a polyimide-based matrix (Matrimid®5218) filled with a Cu-based metal organic framework [MOF, Cu3(BTC)2] with two different ionic liquids (ILs) confined within the pores. The chosen ILs are commonly used in gas solubilization, 1-ethyl-3-methylimidazolium tetrafluoroborate ([EMIM][BF4]) and 1-Ethyl-3-methylimidazolium trifluoromethanesulfonate ([EMIM][OTf]), and the incorporation of the [EMIM][BF4]@Cu-BTC and [EMIM][OTf]@Cu-BTC composites in Matrimid®5218 proved to be an efficient strategy to improve the permeability and selectivity toward CO2/N2 and CO2/CH4 mixtures.
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Entidade financiadora
Fundação para a Ciência e a Tecnologia
Programa de financiamento
5876
Número da atribuição
UID/Multi/04349/2013