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A
Rationalizing the role of the anion in CO2 capture and conversion using imidazolium-based ionic liquid modified mesoporous sílica, Aquino, Aline S., Bernard FL, Borges JV, Mafra Luis, Dalla Vecchia Felipe, Vieira MO, Ligabue R., Chaban VV, Cabrita E. J., and Einloft S. , RSC Advances, Volume 5, p.64220-64227, (2015)
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An Alternative Mechanism for Diels-Alder Reactions of Evans Auxiliary Derivatives, Bakalova, Snezhana M., Duarte Filipe J. S., Georgieva Miglena K., Cabrita Eurico J., and Santos Gil A. , Chemistry-a European Journal, 2009, Volume 15, Number 31, p.7665-7677, (2009) Abstract
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Assessing diffusion in enzyme loaded sol–gel matrices, Barreira, Gustavo, Ferreira Ana S. D., Vidinha Pedro, Cabral Joaquim M. S., Martinho José M. G., Lima João Carlos, Cabrita Eurico J., and Barreiros Susana , RSC Advances, Volume 4, p.25099-25105, (2014) AbstractWebsite

Pulsed field gradient spin echo high resolution magic angle spinning nuclear magnetic resonance spectroscopy is a powerful technique to characterize confined biosystems. We used this approach to assess the diffusion of solvent and reaction species within sol–gel matrices differing in enzyme loading.

Intermolecular interaction as investigated by NOE and diffusion studies, Brand, T., Cabrita E. J., and Berger S. , Progress in Nuclear Magnetic Resonance Spectroscopy, SEP 1 2005, Volume 46, Number 4, p.159-196, (2005) Abstract
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Residue-specific NH exchange rates studied by NMR diffusion experiments, Brand, Torsten, Cabrita Eurico J., Morris Gareth A., Guenther Robert, Hofmann Hans-Jorg, and Berger Stefan , Journal of Magnetic Resonance, JUL 2007, Volume 187, Number 1, p.97-104, (2007) Abstract
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Residue-specific NH exchange rates studied by NMR diffusion experiments (vol 187, pg 97, 2007), Brand, Torsten, Cabrita Eurico J., Morris Gareth A., Guenther Robert, Hofmann Hans-Joerg, and Berger Stefan , Journal of Magnetic Resonance, OCT 2007, Volume 188, Number 2, p.387-387, (2007) Abstract
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Theory and Application of NMR Diffusion Studies , Brand, T., Cabrita E. J., and Berger S. , Modern Magnetic Resonanc, p.131-139, (2006)
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Imide-amide rearrangement of cyclic phosphorimidates: A mechanistic study, Cabrita, E. J., Afonso CAM, and Santos AGD , Chemistry-a European Journal, APR 1 2001, Volume 7, Number 7, p.1455-1467, (2001) Abstract
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High-resolution DOSY NMR with spins in different chemical surroundings: Influence of particle exchange, Cabrita, E. J., Berger S., Brauer P., and Karger J. , Journal of Magnetic Resonance, JUL 2002, Volume 157, Number 1, p.124-131, (2002) Abstract
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HR-DOSY as a new tool for the study of chemical exchange phenomena, Cabrita, E. J., and Berger S. , Magnetic Resonance in Chemistry, DEC 2002, Volume 40, p.S122-S127, (2002) Abstract
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Novel acid catalysed 1,4-addition-type ring-opening polymerisation of cyclic phosphorimidates, Cabrita, E. J., Candeias SX, Ramos A. M., Afonso CAM, and Santos AG , Tetrahedron Letters, JAN 1 1999, Volume 40, Number 1, p.137-140, (1999) Abstract
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DOSY studies of hydrogen bond association: tetramethylsilane as a reference compound for diffusion studies, Cabrita, E. J., and Berger S. , Magnetic Resonance in Chemistry, DEC 2001, Volume 39, p.S142-S148, (2001) Abstract
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Application of HR-MAS NMR in the solid-phase synthesis of a glycopeptide using Sieber amide resin, Carvalho, Luisa R., Corvo Marta C., Enugala Ramu, Marques Manuel M. B., and Cabrita Eurico J. , Magnetic Resonance in Chemistry, APR 2010, Volume 48, Number 4, p.323-330, (2010) Abstract
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Understanding the Ion Jelly Conductivity Mechanism, Carvalho, T., Augusto V., Brás A. R., Lourenço N. M. T., Afonso CAM, Barreiros S., Correia N. T., Vidinha P., Cabrita E. J., Dionísio M., and Roling B. , Journal of Physical Chemistry B, Volume 116, p.2664-2676, (2012) Abstract

The properties of the light flexible device, ion jelly, which combines gelatin with an ionic liquid (IL) were recently reported being promising to develop safe and highly conductive electrolytes. This article aims for the understanding of the ion jelly conductive mechanism using dielectric relaxation spectroscopy (DRS) in the frequency range 10−1−106 Hz; the study was complemented with differential scanning calorimetry (DSC) and pulse field gradient nuclear magnetic resonance (PFG NMR) spectroscopy. The room temperature ionic liquid 1-butyl-3-methylimmidazolium dicyanamide (BMIMDCA) used as received (1.9% w/w water content) and with 6.6% (w/w) of water content and two ion jellies with two different ratios BMIMDCA/gelatin/water % (w/w), IJ1 (41.1/46.7/12.2) and IJ3 (67.8/25.6/6.6), have been characterized. A glass transition was detected by DSC for all materials allowing for classifying them as glass formers. For the ionic liquid, it was observed that the glass transition temperature decreases with the increase of water content. While in subsequent calorimetric runs crystallization was observed for BMIMDCA with negligible water content, no crystallization was detected for any of the ion jelly materials upon themal cycling. To the dielectric spectra of all tested materials, both dipolar relaxation and conductivity contribute; at the lowest frequencies, electrode and interfacial polarization highly dominate. Conductivity, which manifests much more intensity relative to dipolar reorientations, strongly evidences subdiffusive ion dynamics at high frequencies. From dielectric measures, transport properties as mobility and diffusion coefficients were extracted. Data treatment was carried out in order to deconvolute the average diffusion coefficients estimated from dielectric data in its individual contributions of cations (D+) and anions (D−). The D+ values thus obtained for IJ3, the ion jelly with the highest IL/gelatin ratio, cover a large temperature range up to room temperature and revealed excellent agreement with direct measurements from PFG NMR, obeying to the same VFT equation. For BMIMDCA6.6%water, which has the same water amount as IJ3, the diffusion coefficients were only estimated from DRS measurements over a limited temperature range; however, a single VFT equation describes both DRS and PFG NMR data. Moreover, it was found that the diffusion coefficients and mobility are similar for the ionic liquid and IJ3, which points to a role of both water and gelatin weakening the contact ion pair, facilitating the translational motion of ions and promoting its dissociation; nevertheless, it is conceivable that a critical composition of gelatin that leads to those properties. The VFT temperature dependence observed for the conductivity was found to be determined by a similar dependence of the mobility. Both conductivity and segmental motion revealed to be correlated as inferred by the relatively low values of the decoupling indexes. The obtained results show that ion jelly could be in fact a very promising material to design novel electrolytes for different electrochemical devices, having a performance close to the IL but presenting an additional stability regarding electrical measurements and resistance against crystallization relative to the bulk ionic liquid.

Synthesis and evaluation of new benzimidazole-based COX inhibitors: a naproxen-like interaction detected by STD-NMR, Carvalho, L. C. R., Ribeiro D., Seixas R. S. G. R., Silva A. M. S., Nave M., Martins A. C., Erhardt S., Fernandes E., Cabrita E. J., and Marques M. M. B. , RSC Advances, Volume 5, p.49098-49109, (2015) AbstractWebsite

Non-steroidal anti-inflammatory drugs exert their pharmacological activity through inhibition of cyclooxygenase 1 and 2 (COX-1 and COX-2). Recent research suggests that a balanced inhibition of both COX-1 and COX-2 is the key to reduce the side-effects exhibited by COX inhibitors. We developed new benzimidazole-based compounds that showed a balanced COX inhibition, supported by molecular docking screening. The human whole blood assays demonstrated that the ester derivatives were potent inhibitors. Competitive saturation transfer difference (STD)-NMR experiments, in the presence of COX-2, using naproxen and diclofenac demonstrated that ester derivatives do not compete with diclofenac for the same binding site, but compete with the allosteric inhibitor naproxen. Combination of NMR spectroscopy with molecular docking has permitted us to detect a new naproxen-like inhibitor, which could be used for future drug development.

Ion Jelly Conductive Properties Using Dicyanamide-Based Ionic Liquids, Carvalho, T., Augusto V., Rocha A., Lourenco N. M. T., Correia N. T., Barreiros S., Vidinha P., Cabrita E. J., and Dionisio M. , Journal of Physical Chemistry B, Volume 118, Issue 31, p.9445-59, (2014) AbstractWebsite

The thermal behavior and transport properties of several ion jellys (IJs), a composite that results from the combination of gelatin with an ionic liquid (IL), were investigated by dielectric relaxation spectroscopy (DRS), differential scanning calorimetry (DSC), and pulsed field gradient nuclear magnetic resonance spectroscopy (PFG NMR). Four different ILs containing the dicyanamide anion were used: 1-butyl-3-methylimidazolium dicyanamide (BMIMDCA), 1-ethyl-3-methylimidazolium dicyanamide (EMIMDCA), 1-butyl-1-methylpyrrolidinium dicyanamide (BMPyrDCA), and 1-butylpyridinium dicyanamide (BPyDCA); the bulk ILs were also investigated for comparison. A glass transition was detected by DSC for all materials, ILs and IJs, allowing them to be classified as glass formers. Additionally, an increase in the glass transition temperature upon dehydration was observed with a greater extent for IJs, attributed to a greater hindrance imposed by the gelatin matrix after water removal, rendering the IL less mobile. While crystallization is observed for some ILs with negligible water content, it was never detected for any IJ upon thermal cycling, which persist always as fully amorphous materials. From DRS measurements, conductivity and diffusion coefficients for both cations (D+) and anions (D–) were extracted. D+ values obtained by DRS reveal excellent agreement with those obtained from PFG NMR direct measurements, obeying the same VFTH equation over a large temperature range (ΔT ≈ 150 K) within which D+ varies around 10 decades. At temperatures close to room temperature, the IJs exhibit D values comparable to the most hydrated (9%) ILs. The IJ derived from EMIMDCA possesses the highest conductivity and diffusion coefficient, respectively, 10–2 S·cm–1 and 10–10 m2·s–1. For BMPyrDCA the relaxational behavior was analyzed through the complex permittivity and modulus formalism allowing the assignment of the detected secondary relaxation to a Johari–Goldstein process. Besides the relevant information on the more fundamental nature providing physicochemical details on ILs behavior, new doorways are opened for practical applications by using IJ as a strategy to produce novel and stable electrolytes for different electrochemical devices.

Synthesis and characterization of novel γ-induced porous PHEMA–IL composites, Casimiro, MH, Corvo Marta C., Ramos A. M., Cabrita E. J., Ramos A. M., and Ferreira LM , Materials Chemistry and Physics, Volume 138, Issue 1, p.11-16, (2013) AbstractWebsite

A novel porous polymer-ionic liquid composite with poly(2-hydroxyethyl methacrylate) (PHEMA) and 1-butyl-3-methylimidazolium hexafluorophosphate (BMIPF6) has been synthesized by γ-irradiation without heat or chemical initiators. The products can be reversibly converted into organogels. The composites are potential candidates for electrochemical applications. The use of γ-radiation can be a simple and versatile alternative way to obtain these materials.

The Quest for Anticancer Vaccines: Deciphering the Fine-Epitope Specificity of Cancer-Related Monoclonal Antibodies by Combining Microarray Screening and Saturation Transfer Difference NMR, Coelho, Helena, Matsushita T., Artigas G., Hinou H., Cañada FJ, Lo-Man R., Leclerc C., Cabrita E. J., Jiménez-Barbero J., Nishimura S. - I., Garcia-Martín F., and Marcelo F. , J. Am. Chem. Soc., Volume 137, p.12438-12441, (2015)
A rational approach to sustainable CO2-capture by imidazolium ionic liquids: tuning CO2 solubility by cation alkyl branching, Corvo, Marta C., Sardinha João, Casimiro Teresa, Marin Graciane, Seferin Marcus, Einloft Sandra, Menezes Sonia C., Dupont Jairton, and Cabrita Eurico J. , Chem. Sus. Chem., Volume 8, p.1935-1946, (2015)
Solvation of CO2 in [C4mim][BF4] and [C4mim][PF6] ionic liquids revealed by High Pressure NMR, Corvo, Marta C., Sardinha João, Menezes Sonia C., Einloft Sandra, Seferin Marcus, Dupont Jairton, Casimiro Teresa, and Cabrita Eurico J. , Angewandte Chemie International Edition, Volume 49, Issue 52, p.13024-13027, (2013) Website
Analysis of nucleotides binding to chromatography supports provided by nuclear magnetic resonance spectroscopy, Cruz, Carla, Cabrita Eurico J., and Queiroz Joao A. , Journal of Chromatography a, JUN 3 2011, Volume 1218, Number 22, p.3559-3564, (2011) Abstract
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Binding analysis between l-histidine immobilized and oligonucleotides by SPR and NMR, Cruz, Carla, Santos Sandra D., Cabrita Eurico J., and Queiroz João A. , International Journal of Biological Macromolecules, Volume 56, p.175-180, (2013) AbstractWebsite

Saturation transfer difference (STD) NMR technique and surface plasmon resonance (SPR) are used to study amino acid affinity supports–nucleotides interactions with l-histidine amino acid immobilized on a surface as model support. We have immobilized l-histidine ligand on a carboxymethyldextran- modified gold surface intended for surface plasmon resonance and we analyze the binding profiles of synthetic polynucleotides (1–6 base, sugar and backbone) by determining the equilibrium dissociation constant (KD). The SPR binding profile (square-shaped) is identical for all the complexes and the highest binding affinity can be found for polyA6 followed by polyG6 . As expected, the 5′ -mononucleotides have the lowest affinity. To further study the structural aspects of the interaction we investigate the polynucleotide binding preferences to l-histidine chromatography support by STD-NMR spectroscopy. These results revealed that an increase in the number of bases and backbone to 6 units leads to more contacts with the support, where the main driving force for the interaction with polynucleotides are through the base, except for polyC6 , which is mainly through sugar-phosphate backbone. Therefore, the combination of SPR measurements with STD-NMR technique allowed to establish fine details of the molecular recognition process involved in amino acid affinity supports–nucleotides complexes.

Screening nucleotide binding to amino acid-coated supports by surface plasmon resonance and nuclear magnetic resonance, Cruz, Carla, Cabrita Eurico J., and Queiroz Joao A. , Analytical and Bioanalytical Chemistry, AUG 2011, Volume 401, Number 3, p.983-993, (2011) Abstract
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Lewis Acid Catalyzed Reactions of Chiral Imidazolidinones and Oxazolidinones: Insights on the Role of the Catalyst, Duarte, Filipe J. S., Bakalova Snezhana M., Cabrita Eurico J., and Santos Gil A. , Journal of Organic Chemistry, Volume 76, Issue 17, p.6997-7004, (2011) Abstract

The mechanism proposed by Evans to justify the selectivity obtained in Lewis acid catalyzed Diels-Alder reactions of cyclopentadiene with acyloxazolidinones has been generalized and used in the rationalization of selectivities obtained in many other systems. However, we recently proposed an alternative mechanism, on the basis of open-chain mono- and bicomplexes, that avoids the need for chelates and explains the selectivity obtained by Evans. In this manuscript we apply our proposal to the catalyzed conjugated addition of amines to acylimidazolidinones, reported by Cardillo, and we clearly show that aluminum chelates are not involved in the reaction, as they induce no selectivity, while Cardillo observed high experimental selectivities. Our data equally show that bicomplexes with carbonyl parallel orientation, proposed by Cardillo to justify the experimental selectivity with nonchelating Lewis acids, indeed induce the opposite selectivity and have also to be dismissed. On the other hand, our mechanistic proposal allows for the full rationalization of the data obtained by Cardillo with aluminum, boron, or zinc Lewis acids and supports our previous proposal on DA cycloadditions of dienes to Evans chiral auxiliary derivatives.

Density Functional Study of Proline-Catalyzed Intramolecular Baylis-Hillman Reactions, Duarte, Filipe J. S., Cabrita Eurico J., Frenking Gernot, and Santos Gil A. , Chemistry-a European Journal, 2009, Volume 15, Number 7, p.1734-1746, (2009) Abstract
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