Professor at the Federal University of Minas Gerais. It has graduation at Chemistry by Universidade Estadual do Centro-Oeste (2008) , master's at Chemistry by Universidade Estadual de Campinas (2011) , Ph.D. at Chemistry by Universidade Estadual de Campinas (2015) and Postdoctorate by Universidade Estadual de Campinas (2016). It has experience in the area of Chemistry, focused on: Photoreology, TDDFT, Rotational Barriers, Organic Chemistry, DFT.
S- and P-stereogenic heterocycles were synthesized by a remarkably simple enantioselective Heck d... more S- and P-stereogenic heterocycles were synthesized by a remarkably simple enantioselective Heck desymmetrization reaction based on the unprecedented non-covalent directing effect of S=O and P=O functionalities. Selected prochiral symmetric substrates were efficiently arylated using the recently disclosed chiral PyraBOx ligand under mild and open-flask reaction conditions. Several five-membered aryl- sulfones, sulfoxides and phosphine oxides were synthesized in good to excellent yields, in good to high diastereoselectivity, and enantiomeric ratios up to 98:2. Theoretical calculations also support the non-covalent directing effect of the S=O and P=O functionalities during the arylation process.
Wormlike micelles formed by the addition to cetyl-trimethylammonium bromide (CTAB) of a range of ... more Wormlike micelles formed by the addition to cetyl-trimethylammonium bromide (CTAB) of a range of aromatic cosolutes with small molecular variations in their structure were systematically studied. Phenol and derivatives of benzoate and cinnamate were used, and the resulting mixtures were studied by oscillatory, steady-shear rheology, and the microstructure was probed by small-angle neutron scattering. The lengthening of the micelles and their entanglement result in remarkable viscoelastic properties, making rheology a useful tool to assess the effect of structural variations of the cosolutes on wormlike micelle formation. For a fixed concentration of CTAB and cosolute (200 mmol L −1), the relaxation time decreases in the following order: phenol > cinnamate> o-hydroxycinnamate > salicylate > o-methoxycinnamate > benzoate > o-methoxybenzoate. The variations in viscoelastic response are rationalized by using Mulliken population analysis to map out the electronic density of the cosolutes and quantify the barrier to rotation of specific groups on the aromatics. We find that the ability of the group attached to the aromatic ring to rotate is crucial in determining the packing of the cosolute at the micellar interface and thus critically impacts the micellar growth and, in turn, the rheological response. These results enable us for the first time to propose design rules for the self-assembly of the surfactants and cosolutes resulting in the formation of wormlike micelles with the cationic surfactant CTAB.
Enantioselectivec arbonyl-directable Heck reactions using aryldiazonium saltsw ere developed with... more Enantioselectivec arbonyl-directable Heck reactions using aryldiazonium saltsw ere developed with the aim to construct chiral quaternary spiro centers in an efficient manner. Five-a nd six-membered spirooxindoles,s pirolactones,a nd spiro-lactams (36 examples)w ere obtained in good to excellent isolated yieldsw ith diastereoselectivities ranging from 13:1 to > 20:1, and enantiomeric excesses up to 99% in shortr eaction times (1.0–1.5 h) under mild conditions (40 8 8C). Ar ationale for the diastereo-and enantioselectivity based on an unprecedented non-covalent carbonyl group directing effect is also presented, and supported by computational calculations.
Dedicated to the memory of Detlef Schröder for his outstanding contributions to mass spectrometry... more Dedicated to the memory of Detlef Schröder for his outstanding contributions to mass spectrometry To address the title question, the relative intrinsic acidities of phenol and benzoic acid as well as the isomeric family of ortho-, meta-, and para-hydroxybenzoic acids were compared. Dissociation of the [PhCO 2 ···H···OPh] – proton-bound dimer showed slightly greater acidity for benzoic acid. Using traveling-wave ion mobility mass spectrometry (TWIM-MS) with CO 2 as the drift gas and post-TWIM collision-induced dissociation, the gaseous deprotonated molecules of the iso-meric hydroxybenzoic acids were properly separated and characterized. For the para isomer, an intrinsic gas-phase acidity order inverse to that in solution was found, as before, that is, the phenol site of para-hydroxybenzoic acid was found to be considerably more acidic than its benzoic acid
Sand P-Stereogenic heterocycles were synthesized by ar emarkablys imple enantioselective Heck de-... more Sand P-Stereogenic heterocycles were synthesized by ar emarkablys imple enantioselective Heck de-symmetrizationr eactionb ased on the unprecedented noncovalentd irecting effect of S=Oa nd P=Of unctionali-ties. Selected prochiral symmetric substratesw ere efficiently arylated using the recently disclosed chiral PyraBOx ligand under mild and open-flask reaction conditions. Several five-membered aryl-s ulfones, sulfoxides,a nd phos-phine oxidesw eres ynthesized in good to excellent yields, in good to high diastereoselectivity,a nd enantiomeric ratios up to 98:2. Theoretical calculations also support the noncovalentdirecting effect of the S=Oand P=Ofunction-alities during the arylation process.
PdIJITMe) 2 (PhCCPh) acts as a highly reactive pre-catalyst in the unprecedented homogenous cataly... more PdIJITMe) 2 (PhCCPh) acts as a highly reactive pre-catalyst in the unprecedented homogenous catalyzed diboration of terminal and internal alkynes, yielding a number of novel and known syn-1,2-diborylalkenes in a 100% stereoselective manner. DFT calculations suggest that a similar reaction pathway to that proposed for platinum phosphine analogues is followed, and that destabilization of key intermediates by the NHCs is vital to the overall success for the palladium-catalyzed B–B addition to alkynes.
Traveling wave ion mobility mass spectrometry (TWIM-MS) is shown to be able to separate and chara... more Traveling wave ion mobility mass spectrometry (TWIM-MS) is shown to be able to separate and characterize several isomeric forms of diterpene glycosides stevioside (Stv) and rebaudioside A (RebA) that are cationized by Na + and K + at different sites. Determination and characterization of these coexisting isomeric species, herein termed catiomers, arising from cationization at different and highly competitive coordinating sites, is particularly challenging for glycosides. To achieve this goal, the advantage of using CO 2 as a more massive and polarizable drift gas, over N 2 , was demonstrated. Post-TWIM-MS/MS experiments were used to confirm the separation. Optimization of the possible geometries and cross-sectional calculations for mobility peak assignments were also performed.
Ion mobility spectrometry (IMS) separates ions while they travel through a buffer gas under the i... more Ion mobility spectrometry (IMS) separates ions while they travel through a buffer gas under the influence of an electrical field. The separation is affected by mass and charge but most particularly by shape (collision cross section). When coupled to MS, IMS-MS offers therefore a powerful tool for structural elucidation and isomer separation. Systematic studies aimed to compare and quantitate the effects of structural changes on drift time such as length and ramification of carbon chain, unsaturation, geometrical isomerism (cis/trans isomers for instance), cyclization and ring size are, however, scarce. Herein we used traveling wave ion mobility mass spectrometry (TWIM-MS) to systematically evaluate the relationship between structure and drift time. For that, a series of deprotonated carboxylic acids were used as model ions with a carboxylate " charge tag " for gas phase MS manipulation. Carboxylic acids showed a near linear correlation between the increase of carbon number and the increase of collision cross section (CCS). The number of double bonds changes slightly the CCS of unsaturated acids. No differences in drift time and no significant differences in CCS of cis-and trans-double bond of oleic and elaidic acids were observed. Cyclization considerably reduces the CCS. In cyclic carboxylic acids, the increase of double bonds and aromatization significantly reduces the CCS and the drift times. The use of a more polar-izable drift gas, CO 2, improved in some cases the separation , as for biomarker isomers of steranoic acids. The β-isomer (cis-decaline) has smaller CCS and therefore displayed lower drift time compared to the α-isomer (trans-decaline). Structural changes revealed by calculations were correlated with trends in drift times.
Métodos compostos adaptados ao método ONIOM foram utilizados no cálculo teórico de afinidades por... more Métodos compostos adaptados ao método ONIOM foram utilizados no cálculo teórico de afinidades por próton (PA) e eletrônica (EA) para um grupo de 50 moléculas (álcoois, cetonas, radicais e alcenos). A energia eletrônica foi descrita considerando-se o escalonamento de ZPE (λ) e a correção de alto nível (HLC). O valor ótimo para λ foi obtido através dos dados de PA. Os cálculos de EA foram utilizados na otimização dos termos presentes em HLC. Foram explorados diferentes tipos de funcionais de troca-correlação. A metodologia ONIOM2(QCISD(T)/6-311++G(2dF,p):HF/6-31G(d))//ONIOM2(B3LYP/6-31G(d):HF/6-31G(d)) forneceu os menores desvios absolutos médios para PA e EA, 5,38 kJ mol-1 e 0,11 eV, respectivamente, em comparação com dados experimentais. Composite methods adapted to the ONIOM approach were used in the description of proton (PA) and electron (EA) affinities for a group of 50 molecules (alcohols, ketones, radicals and alkenes). The electronic energy was described considering the scaling ZPE (λ) and higher level (HLC) corrections. The optimal value for λ was obtained from the PA data. The EA calculations were used for optimization of the terms in HLC. Different performances of exchange-correlation functionals were considered. The methodology ONIOM2(QCISD(T)/6-311++G(2dF,p):HF/6-31G(d))//ONIOM2(B3LYP/6-31G(d):HF/6-31G(d)) provided the smallest median absolute deviation (MAD) for PA and EA, 5.38 kJ mol-1 and 0.11 eV, respectively, in comparison to the experimental data.
Please cite this article in press as: F.M.A. da Silva, et al., Positive electrospray ionization i... more Please cite this article in press as: F.M.A. da Silva, et al., Positive electrospray ionization ion trap mass spectrometry and ab initio computational studies of the multi-pathway fragmentation of oxoaporphine alkaloids, Int. J. Mass Spectrom. (2016), Positive electrospray ionization ion trap mass spectrometry and ab initio computational studies of the multi-pathway fragmentation of oxoaporphine alkaloids a b s t r a c t We report herein the first collision induced dissociation (CID) study with oxoaporphine alkaloids by electrospray ionization ion-trap mass spectrometry (ESI-IT-MS) associated with ab initio computational studies and isotope labeling experiments. Product ion spectra for a set of 11 oxoaporphine alkaloids were carefully analyzed to assign fragmentation patterns for this natural products class. All common possibilities for different arrangements of the peripheral groups, methylene dioxide bridge, methoxyl, and hydroxyl substituents, were discussed based on MS data and ab initio calculations. We observed that the most suitable protonation site generally occurs on the heterocyclic nitrogen instead of the carbonyl oxygen atom at C-7. In some special cases, a gas-phase proton transfer occurs for compounds bearing a hydroxyl group at C-3, as confirmed by isotope labeling experiments. Results point that the substitution pattern drives the dissociation behaviors of oxoaporphine alkaloids.
Recebido em 16/7/10; aceito em 26/11/10; publicado na web em 9/2/11 COMPUTATIONAL VALIDATION OF C... more Recebido em 16/7/10; aceito em 26/11/10; publicado na web em 9/2/11 COMPUTATIONAL VALIDATION OF COMPOSITE METHODS IN THE STUDY OF MOLECULAR PROPERTIES. Composite methods using ONIOM and different basis sets have been used to calculate proton and electron affinities for a set of alcohols at QCISD(T)/6-311++G(2df,p) level of theory. The study was carried out considering HF, MP2 and DFT (25 exchange correlation functional) methods. The calculation performed at ONIOM2(QCISD(T)/6-311++G(2df,p):HF/6-31G(d))//ONIOM2(O3LYP/6-31G(d):HF/6-31G(d)) resulted in the smallest average absolute deviation for AP and AE, 4,75 kJ/mol e 0,43 eV, respectively.
W1 theory is characterized by a rigorous well-defined series of ab initio calculations not explic... more W1 theory is characterized by a rigorous well-defined series of ab initio calculations not explicitly including any empirical adjustment based on experimental results. To expand its applicability to large molecules , a compact effective pseudopotential was included in its computational procedure and the combination is referred to as W1CEP. The values obtained by W1CEP are very close to the original W1 theory, with a mean absolute deviation of 1.2 kcal mol À1 for W1 and of 1.4 kcal mol À1 for W1CEP. The range of the deviations with a 95% confidence interval are ±3.4 kcal mol À1 for W1 and ±4.0 kcal mol À1 for W1CEP. In addition to accuracy of the results, another important result is that the calculations using W1CEP decrease the CPU time by 13–30%.
Theoretical calculations of the binding energies of metal-polyphenols and metal-cellulose, as wel... more Theoretical calculations of the binding energies of metal-polyphenols and metal-cellulose, as well as the hydration energies of metal-polyphenols were used to support the results obtained for the bioaccessibility of aluminium, cadmium, iron and zinc from four types of lettuce and one type of cole that were evaluated using an in vitro gastrointestinal digestion model and inductively coupled plasma-mass spectrometry. The bioaccessibility of Al found in the vegetables were less than 11% of the total Al content, whereas Cd exhibited average bioaccessibility of approximately 14% for the fresh samples and 41% considering the dried vegetables studied. However, the results indicated average bioaccessibility of 35% and 26% for Zn and average bioaccessibility of 19% and 21% for Fe in fresh and dried samples, respectively. The low bioaccessibility of Al is due to its strong binding with all of the vegetable components, whereas the low bioaccessibility of Fe and Zn are due to their interactions with phytates. Cd was observed to be the most bioaccessible element in the dried samples because of its weak interaction with other components in the vegetables.
S- and P-stereogenic heterocycles were synthesized by a remarkably simple enantioselective Heck d... more S- and P-stereogenic heterocycles were synthesized by a remarkably simple enantioselective Heck desymmetrization reaction based on the unprecedented non-covalent directing effect of S=O and P=O functionalities. Selected prochiral symmetric substrates were efficiently arylated using the recently disclosed chiral PyraBOx ligand under mild and open-flask reaction conditions. Several five-membered aryl- sulfones, sulfoxides and phosphine oxides were synthesized in good to excellent yields, in good to high diastereoselectivity, and enantiomeric ratios up to 98:2. Theoretical calculations also support the non-covalent directing effect of the S=O and P=O functionalities during the arylation process.
Wormlike micelles formed by the addition to cetyl-trimethylammonium bromide (CTAB) of a range of ... more Wormlike micelles formed by the addition to cetyl-trimethylammonium bromide (CTAB) of a range of aromatic cosolutes with small molecular variations in their structure were systematically studied. Phenol and derivatives of benzoate and cinnamate were used, and the resulting mixtures were studied by oscillatory, steady-shear rheology, and the microstructure was probed by small-angle neutron scattering. The lengthening of the micelles and their entanglement result in remarkable viscoelastic properties, making rheology a useful tool to assess the effect of structural variations of the cosolutes on wormlike micelle formation. For a fixed concentration of CTAB and cosolute (200 mmol L −1), the relaxation time decreases in the following order: phenol > cinnamate> o-hydroxycinnamate > salicylate > o-methoxycinnamate > benzoate > o-methoxybenzoate. The variations in viscoelastic response are rationalized by using Mulliken population analysis to map out the electronic density of the cosolutes and quantify the barrier to rotation of specific groups on the aromatics. We find that the ability of the group attached to the aromatic ring to rotate is crucial in determining the packing of the cosolute at the micellar interface and thus critically impacts the micellar growth and, in turn, the rheological response. These results enable us for the first time to propose design rules for the self-assembly of the surfactants and cosolutes resulting in the formation of wormlike micelles with the cationic surfactant CTAB.
Enantioselectivec arbonyl-directable Heck reactions using aryldiazonium saltsw ere developed with... more Enantioselectivec arbonyl-directable Heck reactions using aryldiazonium saltsw ere developed with the aim to construct chiral quaternary spiro centers in an efficient manner. Five-a nd six-membered spirooxindoles,s pirolactones,a nd spiro-lactams (36 examples)w ere obtained in good to excellent isolated yieldsw ith diastereoselectivities ranging from 13:1 to > 20:1, and enantiomeric excesses up to 99% in shortr eaction times (1.0–1.5 h) under mild conditions (40 8 8C). Ar ationale for the diastereo-and enantioselectivity based on an unprecedented non-covalent carbonyl group directing effect is also presented, and supported by computational calculations.
Dedicated to the memory of Detlef Schröder for his outstanding contributions to mass spectrometry... more Dedicated to the memory of Detlef Schröder for his outstanding contributions to mass spectrometry To address the title question, the relative intrinsic acidities of phenol and benzoic acid as well as the isomeric family of ortho-, meta-, and para-hydroxybenzoic acids were compared. Dissociation of the [PhCO 2 ···H···OPh] – proton-bound dimer showed slightly greater acidity for benzoic acid. Using traveling-wave ion mobility mass spectrometry (TWIM-MS) with CO 2 as the drift gas and post-TWIM collision-induced dissociation, the gaseous deprotonated molecules of the iso-meric hydroxybenzoic acids were properly separated and characterized. For the para isomer, an intrinsic gas-phase acidity order inverse to that in solution was found, as before, that is, the phenol site of para-hydroxybenzoic acid was found to be considerably more acidic than its benzoic acid
Sand P-Stereogenic heterocycles were synthesized by ar emarkablys imple enantioselective Heck de-... more Sand P-Stereogenic heterocycles were synthesized by ar emarkablys imple enantioselective Heck de-symmetrizationr eactionb ased on the unprecedented noncovalentd irecting effect of S=Oa nd P=Of unctionali-ties. Selected prochiral symmetric substratesw ere efficiently arylated using the recently disclosed chiral PyraBOx ligand under mild and open-flask reaction conditions. Several five-membered aryl-s ulfones, sulfoxides,a nd phos-phine oxidesw eres ynthesized in good to excellent yields, in good to high diastereoselectivity,a nd enantiomeric ratios up to 98:2. Theoretical calculations also support the noncovalentdirecting effect of the S=Oand P=Ofunction-alities during the arylation process.
PdIJITMe) 2 (PhCCPh) acts as a highly reactive pre-catalyst in the unprecedented homogenous cataly... more PdIJITMe) 2 (PhCCPh) acts as a highly reactive pre-catalyst in the unprecedented homogenous catalyzed diboration of terminal and internal alkynes, yielding a number of novel and known syn-1,2-diborylalkenes in a 100% stereoselective manner. DFT calculations suggest that a similar reaction pathway to that proposed for platinum phosphine analogues is followed, and that destabilization of key intermediates by the NHCs is vital to the overall success for the palladium-catalyzed B–B addition to alkynes.
Traveling wave ion mobility mass spectrometry (TWIM-MS) is shown to be able to separate and chara... more Traveling wave ion mobility mass spectrometry (TWIM-MS) is shown to be able to separate and characterize several isomeric forms of diterpene glycosides stevioside (Stv) and rebaudioside A (RebA) that are cationized by Na + and K + at different sites. Determination and characterization of these coexisting isomeric species, herein termed catiomers, arising from cationization at different and highly competitive coordinating sites, is particularly challenging for glycosides. To achieve this goal, the advantage of using CO 2 as a more massive and polarizable drift gas, over N 2 , was demonstrated. Post-TWIM-MS/MS experiments were used to confirm the separation. Optimization of the possible geometries and cross-sectional calculations for mobility peak assignments were also performed.
Ion mobility spectrometry (IMS) separates ions while they travel through a buffer gas under the i... more Ion mobility spectrometry (IMS) separates ions while they travel through a buffer gas under the influence of an electrical field. The separation is affected by mass and charge but most particularly by shape (collision cross section). When coupled to MS, IMS-MS offers therefore a powerful tool for structural elucidation and isomer separation. Systematic studies aimed to compare and quantitate the effects of structural changes on drift time such as length and ramification of carbon chain, unsaturation, geometrical isomerism (cis/trans isomers for instance), cyclization and ring size are, however, scarce. Herein we used traveling wave ion mobility mass spectrometry (TWIM-MS) to systematically evaluate the relationship between structure and drift time. For that, a series of deprotonated carboxylic acids were used as model ions with a carboxylate " charge tag " for gas phase MS manipulation. Carboxylic acids showed a near linear correlation between the increase of carbon number and the increase of collision cross section (CCS). The number of double bonds changes slightly the CCS of unsaturated acids. No differences in drift time and no significant differences in CCS of cis-and trans-double bond of oleic and elaidic acids were observed. Cyclization considerably reduces the CCS. In cyclic carboxylic acids, the increase of double bonds and aromatization significantly reduces the CCS and the drift times. The use of a more polar-izable drift gas, CO 2, improved in some cases the separation , as for biomarker isomers of steranoic acids. The β-isomer (cis-decaline) has smaller CCS and therefore displayed lower drift time compared to the α-isomer (trans-decaline). Structural changes revealed by calculations were correlated with trends in drift times.
Métodos compostos adaptados ao método ONIOM foram utilizados no cálculo teórico de afinidades por... more Métodos compostos adaptados ao método ONIOM foram utilizados no cálculo teórico de afinidades por próton (PA) e eletrônica (EA) para um grupo de 50 moléculas (álcoois, cetonas, radicais e alcenos). A energia eletrônica foi descrita considerando-se o escalonamento de ZPE (λ) e a correção de alto nível (HLC). O valor ótimo para λ foi obtido através dos dados de PA. Os cálculos de EA foram utilizados na otimização dos termos presentes em HLC. Foram explorados diferentes tipos de funcionais de troca-correlação. A metodologia ONIOM2(QCISD(T)/6-311++G(2dF,p):HF/6-31G(d))//ONIOM2(B3LYP/6-31G(d):HF/6-31G(d)) forneceu os menores desvios absolutos médios para PA e EA, 5,38 kJ mol-1 e 0,11 eV, respectivamente, em comparação com dados experimentais. Composite methods adapted to the ONIOM approach were used in the description of proton (PA) and electron (EA) affinities for a group of 50 molecules (alcohols, ketones, radicals and alkenes). The electronic energy was described considering the scaling ZPE (λ) and higher level (HLC) corrections. The optimal value for λ was obtained from the PA data. The EA calculations were used for optimization of the terms in HLC. Different performances of exchange-correlation functionals were considered. The methodology ONIOM2(QCISD(T)/6-311++G(2dF,p):HF/6-31G(d))//ONIOM2(B3LYP/6-31G(d):HF/6-31G(d)) provided the smallest median absolute deviation (MAD) for PA and EA, 5.38 kJ mol-1 and 0.11 eV, respectively, in comparison to the experimental data.
Please cite this article in press as: F.M.A. da Silva, et al., Positive electrospray ionization i... more Please cite this article in press as: F.M.A. da Silva, et al., Positive electrospray ionization ion trap mass spectrometry and ab initio computational studies of the multi-pathway fragmentation of oxoaporphine alkaloids, Int. J. Mass Spectrom. (2016), Positive electrospray ionization ion trap mass spectrometry and ab initio computational studies of the multi-pathway fragmentation of oxoaporphine alkaloids a b s t r a c t We report herein the first collision induced dissociation (CID) study with oxoaporphine alkaloids by electrospray ionization ion-trap mass spectrometry (ESI-IT-MS) associated with ab initio computational studies and isotope labeling experiments. Product ion spectra for a set of 11 oxoaporphine alkaloids were carefully analyzed to assign fragmentation patterns for this natural products class. All common possibilities for different arrangements of the peripheral groups, methylene dioxide bridge, methoxyl, and hydroxyl substituents, were discussed based on MS data and ab initio calculations. We observed that the most suitable protonation site generally occurs on the heterocyclic nitrogen instead of the carbonyl oxygen atom at C-7. In some special cases, a gas-phase proton transfer occurs for compounds bearing a hydroxyl group at C-3, as confirmed by isotope labeling experiments. Results point that the substitution pattern drives the dissociation behaviors of oxoaporphine alkaloids.
Recebido em 16/7/10; aceito em 26/11/10; publicado na web em 9/2/11 COMPUTATIONAL VALIDATION OF C... more Recebido em 16/7/10; aceito em 26/11/10; publicado na web em 9/2/11 COMPUTATIONAL VALIDATION OF COMPOSITE METHODS IN THE STUDY OF MOLECULAR PROPERTIES. Composite methods using ONIOM and different basis sets have been used to calculate proton and electron affinities for a set of alcohols at QCISD(T)/6-311++G(2df,p) level of theory. The study was carried out considering HF, MP2 and DFT (25 exchange correlation functional) methods. The calculation performed at ONIOM2(QCISD(T)/6-311++G(2df,p):HF/6-31G(d))//ONIOM2(O3LYP/6-31G(d):HF/6-31G(d)) resulted in the smallest average absolute deviation for AP and AE, 4,75 kJ/mol e 0,43 eV, respectively.
W1 theory is characterized by a rigorous well-defined series of ab initio calculations not explic... more W1 theory is characterized by a rigorous well-defined series of ab initio calculations not explicitly including any empirical adjustment based on experimental results. To expand its applicability to large molecules , a compact effective pseudopotential was included in its computational procedure and the combination is referred to as W1CEP. The values obtained by W1CEP are very close to the original W1 theory, with a mean absolute deviation of 1.2 kcal mol À1 for W1 and of 1.4 kcal mol À1 for W1CEP. The range of the deviations with a 95% confidence interval are ±3.4 kcal mol À1 for W1 and ±4.0 kcal mol À1 for W1CEP. In addition to accuracy of the results, another important result is that the calculations using W1CEP decrease the CPU time by 13–30%.
Theoretical calculations of the binding energies of metal-polyphenols and metal-cellulose, as wel... more Theoretical calculations of the binding energies of metal-polyphenols and metal-cellulose, as well as the hydration energies of metal-polyphenols were used to support the results obtained for the bioaccessibility of aluminium, cadmium, iron and zinc from four types of lettuce and one type of cole that were evaluated using an in vitro gastrointestinal digestion model and inductively coupled plasma-mass spectrometry. The bioaccessibility of Al found in the vegetables were less than 11% of the total Al content, whereas Cd exhibited average bioaccessibility of approximately 14% for the fresh samples and 41% considering the dried vegetables studied. However, the results indicated average bioaccessibility of 35% and 26% for Zn and average bioaccessibility of 19% and 21% for Fe in fresh and dried samples, respectively. The low bioaccessibility of Al is due to its strong binding with all of the vegetable components, whereas the low bioaccessibility of Fe and Zn are due to their interactions with phytates. Cd was observed to be the most bioaccessible element in the dried samples because of its weak interaction with other components in the vegetables.
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