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Projeto de investigação
Centro de Química Estrutural
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Publication . Morais, Tânia S.; Fernandes, Alexandra R.; Baptista, Pedro V.; Gambino, Dinorah; UCIBIO - Applied Molecular Biosciences Unit; DCV - Departamento de Ciências da Vida; Frontiers Media
A bio-based alginate aerogel as an ionic liquid support for the efficient synthesis of cyclic carbonates from co2 and epoxides
Publication . Paninho, Ana B.; Mustapa, Ana N.; Mahmudov, Kamran T.; Pombeiro, Armando J. L.; Guedes da Silva, M. Fátima C.; Bermejo, María D.; Martín, Ángel; Cocero, María J.; Nunes, Ana V. M.; LAQV@REQUIMTE; DQ - Departamento de Química; MDPI - Multidisciplinary Digital Publishing Institute
In this work, the ionic liquid [Aliquat][Cl] was supported into alginate and silica aerogel matrices and applied as a catalyst in the cycloaddition reaction between CO2 and a bio-based epoxide (limonene oxide). The efficiency of the alginate aerogel system is much higher than that of the silica one. The method of wet impregnation was used for the impregnation of the aerogel with [Aliquat][Cl] and a zinc complex. The procedure originated a well-defined thin solvent film on the surface of support materials. Final materials were characterised by Fourier Transform Infrared Spectroscopy, N2 Adsorption–Desorption Analysis, X-ray diffraction, atomic absorption and Field Emission Scanning Microscopy. Several catalytic tests were performed in a high-pressure apparatus at 353.2 K and 4 MPa of CO2.
Evidence of Strong Guest–Host Interactions in Simvastatin Loaded in Mesoporous Silica MCM-41
Publication . Cordeiro, Teresa; Matos, Inês; Danède, Florence; Sotomayor, João C.; Fonseca, Isabel M.; Corvo, Marta C.; Dionísio, Madalena; Viciosa, María Teresa; Affouard, Frédéric; Correia, Natália T.; LAQV@REQUIMTE; DQ - Departamento de Química; DCM - Departamento de Ciência dos Materiais; CENIMAT-i3N - Centro de Investigação de Materiais (Lab. Associado I3N); MDPI AG
A rational design of drug delivery systems requires in-depth knowledge not only of the drug itself, in terms of physical state and molecular mobility, but also of how it is distributed among a carrier and its interactions with the host matrix. In this context, this work reports the behavior of simvastatin (SIM) loaded in mesoporous silica MCM-41 matrix (average pore diameter ~3.5 nm) accessed by a set of experimental techniques, evidencing that it exists in an amorphous state (X-ray diffraction, ssNMR, ATR-FTIR, and DSC). The most significant fraction of SIM molecules corresponds to a high thermal resistant population, as shown by thermogravimetry, and which interacts strongly with the MCM silanol groups, as revealed by ATR-FTIR analysis. These findings are supported by Molecular Dynamics (MD) simulations predicting that SIM molecules anchor to the inner pore wall through multiple hydrogen bonds. This anchored molecular fraction lacks a calorimetric and dielectric signature corresponding to a dynamically rigid population. Furthermore, differential scanning calorimetry showed a weak glass transition that is shifted to lower temperatures compared to bulk amorphous SIM. This accelerated molecular population is coherent with an in-pore fraction of molecules distinct from bulklike SIM, as highlighted by MD simulations. MCM-41 loading proved to be a suitable strategy for a long-term stabilization (at least three years) of simvastatin in the amorphous form, whose unanchored population releases at a much higher rate compared to the crystalline drug dissolution. Oppositely, the surface-attached molecules are kept entrapped inside pores even after long-term release assays.
Irradiation-responsive polysulfone film as a colorimetric UVA/UVB differentiator
Publication . Monteiro, Bernardo; Leal, João Paulo; Outis, Mani; Casimiro, Maria Helena; Pereira, Cláudia C. L.; LAQV@REQUIMTE; DQ - Departamento de Química; RSC - Royal Society of Chemistry
A wearable, small size, flexible and energy consumable free colorimetric detector of UVA radiation and UVB/UVA differentiation was created based on the peculiar stimuli-responsive behaviour of an imidazolium based ionic liquid. Semi-transparent polysulfone films are transformed into opaque and homogenous red films under UVA radiation (315-360 nm), while lower wavelength exposure (280-315 nm) induces increased emission detectable under dark light, with no colour modification of the film under visible light. Thermal analysis (TGA and DSC), spectroscopic analysis (FT-IR, 1H-NMR and UV-Vis), scanning electronic microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS) were conducted to elucidate confinement mechanism and irradiation effects.
Triazaphosphaadamantane-functionalized terpyridine metal complexes
Publication . Librando, Ivy L.; Paul, Anup; Mahmoud, Abdallah G.; Gurbanov, Atash V.; Carabineiro, Sónia A. C.; Silva, M. Fátima C. Guedes da; Geraldes, Carlos F. G. C.; Pombeiro, Armando J. L.; LAQV@REQUIMTE; DQ - Departamento de Química; RSC - Royal Society of Chemistry
In accordance with UN's Sustainable Development Goal (UN's SDG) 12 which encompasses the sustainable use of chemical products and a sound circular economy, this work is focused on the synthesis of Co(II), Ni(II) and Mn(II) complexes bearing combined 1,3,5-triaza-7-phosphaadamantane and benzyl terpyridine core moieties (PTA–Bztpy) as ligand, followed by their evaluation as catalysts for the microwave-assisted cyclohexane oxidation using tert-butyl hydroperoxide (TBHP) as oxidant. The most active catalyst, with a manganese metal center, was heterogenized on six different carbon materials. The results disclosed the influence of several reaction parameters, such as catalyst loading, temperature, reaction time and solvent, on the catalytic activity and selectivity of the homogeneous and carbon-supported catalysts. Recyclability of the carbon-supported catalyst allowed facile separations, recovery and reuse for five consecutive cycles.
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Entidade financiadora
Fundação para a Ciência e a Tecnologia
Programa de financiamento
6817 - DCRRNI ID
Número da atribuição
UIDB/00100/2020