The antioxidative potential of flavonoids was one of the earliest functions proposed for these co... more The antioxidative potential of flavonoids was one of the earliest functions proposed for these compounds. The grafting of the rootstock with the orange tree is an agronomical technique used to improve production and quality of the fruit. Ethanolic extracts of peel citrus fruit grafted on 8 rootstocks growing in Tunisia were investigated for their total flavonoids content and their antioxidant activity by radical DPPH method. IC50 (values denote the concentration of sample, which is required to scavenge50% of radical DPPH free radicals) for antioxidant activity ranged from 585.4-1095.1 μg/mL. Total flavonoids content (based on colorimetric AlCl3 method) varied from 11.44-44.34 mg Quercetin equivalent/g of dry extract. There were a correlation between the total flavonoids contents and antioxidant activity of peel extracts (r=-0.8654).
HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific r... more HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.
Here a biological investigationof various extract f rom T. ramosissimum (FamilyLamiaceae), an end... more Here a biological investigationof various extract f rom T. ramosissimum (FamilyLamiaceae), an endemic species from North Africa. Several co mp nents were extracted from the aerial parts using hexane, ethyl acetate, acetone and ethanol. These extracts were then investigated for their effect on two cancer cell lines (MCF-7 and HCT-116). Cytotoxicity of these extracts was measur ed using a colorimetric MTT assay. The results showed that the component extrac ted with ethanol, was the most cytotoxic on all cancer cells tested (IC 50=6 and 17μg/ml for MCF-7 and HCT-116 cell lines, respectively). Furthermore, these extracts w ere screened for their antiinflammatory activity against 5-lipoxygenase enzyme and for their anti-Alzheimer activity against the acetylcholinesterase enzyme. A ll extracts (hexane, ethyl acetate, acetone and ethanol) showed a low inhibition level on 5-lipoxygenase enzyme, 19.1, 39.7, 40.6 and 23.76%, respectively (at 60μg/ml). I n the anti-Alzheimer activity at 60μg/m...
In this work, we theoretically study the hydrogenation reaction of disubstituted cyclopentene 1a-... more In this work, we theoretically study the hydrogenation reaction of disubstituted cyclopentene 1a-d by the (Z)1,2-diazene 2 and by (E)-1,2-diazene 2'. DFT/B3LYP calculations with 6-311G** standard basis set, explain the possibility and the stereoselectivity of these reactions. The transition states of the reaction between (Z)-1,2diazene 2 and disubstituted cyclopentene 1a-d have been calculated and discussed.
Essential oils are a mixture of various compounds that can have acted against insect pests throug... more Essential oils are a mixture of various compounds that can have acted against insect pests through complex mechanisms. Their constituents were shown to be a potent source of biological pesticides. The aims of the present study are to characterize the chemical composition and evaluate the aphidicidal activities of Tunisian Melaleuca styphelioides leaves essential oil. Fumigant and contact toxicities were determined against three major aphid infecting citrus trees: Aphis gossypi, Aphis spiraecola and Myzus persicae. The chemical composition of this oil was characterized by GC-MS. The major common compounds were caryophyllene oxide (23.42%), spathulenol (20.5%), isoaromadendrene epoxide (7.45%), ledol (5.98%), and α-pinene (3.82%).The results showed that M. styphelioides essential oil has a good fumigant and contact toxicity against the three citrus aphids tested. The highest activity was registered on A. spiraecola nymphs (LC 50 = 44.72 μL/L air for the fumigant activity and 115.93 μL/L for the contact toxicity). The adults of A. gossypii seem to be more resistant to essential oil in the contact bioassay with an LC 50 = 3660.99 μL/L. Overall, our work proposes the use of the M. styphelioides essential oil as contact and fumigant bio-insecticides against resistant citrus aphids.
Seeking to explore new local natural resources, volatile profile as well as essential oil composi... more Seeking to explore new local natural resources, volatile profile as well as essential oil compositions of Tunisian Borago officinalis L. were analyzed. The current study aims at investigating the effects of the geographic origin and the plant part (flowers, leaves, and rosettes leaves) on the volatile profile of Borago officinalis L. The aerial parts were collected from three bioclimate zones in Tunisia namely Tunis, Bizerte, and Zaghouan. The essential oils were extracted by hydro distillation. The chemical composition of the latter was determined by gas chromatography coupled to mass spectrometry. Furthermore, an experimental procedure combining solid phase microextraction and gas chromatography coupled to mass spectrometry was implemented to study the volatile profile of Borago officinalis L. It was set up to assess the influence of different plant organs obtained from various sites on the aromatic profile. Essential oil yields ranged from 0.14 ± 0.00% to 0.18 ± 0.01%. Benzenacetaldehyde was the major compound of the essential oils (7.11-9.16%). Chromatographic analysis revealed that the chemical compositions vary considerably from one region to another. The ones extracted from Bizerte and Zaghouan collections were characterized by the predominance of aldehydes (27.02% and 35.16%), followed by oxygenated monoterpenes (20.64% and 20.58%). The essential oils obtained from the third collection (Tunis) showed the predominance of oxygenated monoterpenes (27.23%), followed by aldehydes (23.93%) and oxygenated sesquiterpenes (12.22%). The aldehydes were identified as the major chemical class in the flowers' volatile compounds dominated by octanal (13.32-16.42%) as well as in the leaves where nonanal was the major one (10.49-11.55%). In the rosettes aromatic profile, the oxygenated monoterpenes were the main chemical class with a percentage ranging from 39.45 to 46.64%. A relatively high content of acids (10.15%) was exclusively determined in Zaghouan flowers' volatile profile. Principal Component Analyses and Hierarchical Clustering Analyses were pertinent tools to differentiate the volatile fractions. The findings showed a remarkable difference and significant variations in quality and quantity of the secondary metabolites.
International Symposium on Medicinal and Aromatic Plants - SIPAM2009, 2010
La valorisation des plantes aromatiques et médicinales passe obligatoirement par l'extraction de ... more La valorisation des plantes aromatiques et médicinales passe obligatoirement par l'extraction de leurs huiles essentielles. Or cette extraction est confrontée, entre autres, à la faible teneur en huile essentielle dans la matière végétale. Par conséquent, des solutions technologiques, permettant la récupération aussi complète que possible des huiles essentielles de bonne qualité, sont à rechercher même lorsqu'il s'agit du plus ancien des procédés d'extraction. En outre, si les techniques extractives ont gardé, au cours des siècles, leurs principes de base, la recherche dans ce domaine s'est orientée vers la maîtrise et l'optimisation des paramètres liés aussi bien aux particularités de la matière végétale à traiter, qu'au procédé lui-même afin d'obtenir un produit de bonne qualité et de minimiser le temps d'extraction. C'est dans ce cadre que se situe notre travail qui vise à déterminer les conditions opératoires optimales d'extraction de huile essentielle du myrte obtenues par le procédé d'hydrodistillation à l'échelle du laboratoire. L'étude a porté sur trois facteurs à savoir : la durée d'exposition de la matière végétale aux ultrasons, le rapport masse de la matière végétale/masse d'eau, et le débit de condensation. L'optimisation a été réalisée dans un premier temps par une méthode paramétrique, puis en deuxième temps selon la méthode de la planification des expériences en utilisant un plan factoriel complet 2 3 . Ce plan associé à un modèle mathématique sous forme de polynôme du premier degré, a permis de calculer la réponse moyenne, les effets des facteurs ainsi que leurs interactions. Les résultats ont montré que le rapport masse de la matière végétale/masse d'eau et le débit de condensation ont un effet significatif (en valeur absolue) sur le rendement en huiles essentielles du myrte (respectivement -0,137 et 0,095) alors que le facteur d'ultrasons a montré un effet négligeable (de l'ordre de -0,045). Le rendement en huile essentielle récupérée à partir de 50 g de feuilles de myrte est, en moyenne de 0,87%.
International Symposium on Medicinal and Aromatic Plants - SIPAM2009, 2010
During the past few decades, the need for safer means of pest management have become crucial due ... more During the past few decades, the need for safer means of pest management have become crucial due to the harmful effects of synthetic insecticides on the environment, problems related to pests' resurgence and resistance to pesticide and risk for users. Therefore, a growing interest in research concerning the possible use of plant extracts as alternatives to synthetic insecticides was developed. In this study, we report first investigations on chemical constituents and fumigant toxicity of Pistacia lentiscus L. (Anacardiacea) essential oil against 1-7 day-old adults of Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae) and Lasioderma serricorne (F.) (Coleoptera: Anobiidae). The major compounds of the essential oil determined using the GC and the GC-MS were: α-phellandrene (3.20%), α-pinene (9.48%) and limonene (19.11%). Oil amounts tested were 5 and 45 µl in each 44 ml Plexiglas bottle with capacity corresponding to concentrations 114 and 1023 µl/L air. Great differences in insect mortality were observed within insect species, oil concentrations and exposure time. The fumigant toxicity potential of P. lentiscus on L. serricorne was higher (LC 50 = 8.44 µl/L, LC 95 = 43.68 µl/L) than T. castaneum (LC 50 =28.03 µl/L, LC 95 =63.46 µl/L). The results suggested that P. lentiscus essential oil may have potential as a control agent against these two stored product beetles.
The authors have evaluated the temperature dependence of the tight-binding transfer integral betw... more The authors have evaluated the temperature dependence of the tight-binding transfer integral between neighbouring cation molecules for some representative compounds of the (TMTSF)2X and (TMTTF)2X families using their recently determined low-temperature and/or high-pressure crystallographic structures. The changes in the transverse integrals in going from the new structures to the ambient temperature and pressure structures are largest for those integrals which
Tin tetrachloride adducts of the type SnCl4·2L (L=(Me2N)3P(O) (1), (Me2N)2P(O)F (2), Me2NP(O)F2 (... more Tin tetrachloride adducts of the type SnCl4·2L (L=(Me2N)3P(O) (1), (Me2N)2P(O)F (2), Me2NP(O)F2 (3) and P(O)F3 (4)) have been theoretically studied by means of DFT geometry optimisation (B3LYP/LANL2DZ) and 119Sn chemical shift calculations (B3LYP/SV). A good correlation was found between calculated and experimental data. On going from complex 1 to 4, the SnL bond underwent considerable lengthening, while that of SnCl was shortened (SnO: 2.11 in cis-1 vs. 2.37Å in cis-4; SnCl: 2.43 in cis-1 vs. 2.37Å in cis-4). In the same way, the SnOP bond angle was found to decrease from 147° for cis-1 to 136° for cis-4. The trends are in good agreement with the calculated metal–ligand binding energies of complexes 1–4. Interestingly, the structural changes are accompanied by increased 119Sn chemical shifts towards higher frequencies as the Me2N groups in the ligand are substituted by fluorine atoms. The theoretical results showed that the use of the all-electron SV basis set for tin, together with the 6-31G∗ basis set for the other atoms could efficiently predict the 119Sn NMR chemical shifts in the complexes SnCl4·2L.
ABSTRACT In this theoretical work, we computed the equilibrium geometries and a set of rotational... more ABSTRACT In this theoretical work, we computed the equilibrium geometries and a set of rotational and vibrational spectroscopic parameters for cyano substituted 2-pyridones neutral or cationic and their tautomers (cyano 2-hydroxypyridines). We examined also the effect of tautomerism equilibrium on those systems. In our analysis, we mostly focused on the perturbations induced by the CN group on the electronic structure and on the spectroscopy of 2-pyridone / 2-hydroxypyridine block. Moreover, we investigated the pattern of their low lying electronic states at both the PBE0/aug-cc-pVDZ Density Functional Theory (DFT) and the CASSCF/aug-cc-pVTZ levels of theory. Vertical excitation spectra and both adiabatic and vertical ionization energies were performed.
Impregnation of size-selected titanium-oxo-alkoxy nanoparticles into monolithic ultraporous alumi... more Impregnation of size-selected titanium-oxo-alkoxy nanoparticles into monolithic ultraporous alumina (UPA) permits nanoparticulate photocatalytic media with an extended activity into the high-temperature range up to 1000 °C, which is explained by anatase TiO 2 phase stability due to the inhibited nanoparticles aggregation. In this Article we report on the effect of the nanoparticle polymorphism and size on the photocatalytic ethylene gas decomposition. Use of UPA supports of γ, θ, and α polymorphs, covered with silica or not, and thermal treatment at different temperatures allow modification of the nanoparticles size and crystalline composition. In all cases, the interaction between titania and UPA support is found to affect the polymorph stability. In particular, a separating layer of silica increases the temperature of the anatase-rutile transformation. The main conclusion is that anatase nanoparticles exhibit the higher activity compared to rutile and composite anatase/rutile nanoparticles. The rutile activity strongly decreases with size 2R ≥ 5 nm, while that of anatase nanoparticles does not appreciably change for sizes 5 nm ≤ 2R ≤ 10 nm. The material activity strongly decreases when rutile phase is nucleated onto the anatase one.
A systematic theoretical DFT study of the bonding between the cation Fe 3C and the anion H 2 PO 4... more A systematic theoretical DFT study of the bonding between the cation Fe 3C and the anion H 2 PO 4 K was carried out. By interesting in tetrahedral, bipyramidal and octahedral environments around the iron ion, several isomers were studied and their geometries were established in each case. Calculated infra-red spectra were also done.
The crystallographic structures under constraints of representatives salts of the title families ... more The crystallographic structures under constraints of representatives salts of the title families lead to unexpected variations of the corresponding band structures and Fermi surfaces. We discuss in this study the role of the anion size for X-=ClO4,Re04 on the transfer integrals magnitude at different temperatures. For (TMTSF)2ReO 4 at 125K, the two inequivalent dimers resulting from the anion ordering along a lead to a calculated site energy difference of 72 meV. For the same salt, it is found that in the 125K averaged structure, the interchain transfer integrals are very close to the (TMTSF)2CIO 4 ones. Thus, it would be mainly the a-axis anion ordering which prevents at low T and ambient pressure the appearance of SC in the Re04 salt.
Crystallographic structures of (TNTSF)~ PF6 at low temperature (T=4K) or under joint T and P effe... more Crystallographic structures of (TNTSF)~ PF6 at low temperature (T=4K) or under joint T and P effects (T=I.TK~ P=TXlO2fPa) have been investigated. Results are compared to those obtained at room temperature when pressure is applied up to lO×lO=KPa. Evidence is thus given of non-cumulative temperature and pressure effects on the 'rfTsF packing, The calculated transfer integrals are discussed in relation to their room temperature and ambient pressure values, Induced changes in the Fermi surface are presented, They lead to a close dependence of the nesting vector with T and/or P experimental conditions, At T=I,TK~ P=TxIO~IiPa, the calculated nesting vector is nearly (2k~,x/2b) pointing to a SD¥ wave vector close to (1/2,114).
The G3(MP2) method has been employed to study the 1,4-addition reactions between singlet oxygen a... more The G3(MP2) method has been employed to study the 1,4-addition reactions between singlet oxygen and five acenes, including benzene, naphthalene, anthrecene, tetracene, and pentacene. In all, nine pathways between O 2 and the five acenes have been investigated. Our calculated results indicate that all nine pathways are concerted and exothermic and that the most reactive sites on the acenes are the center ring's meso-carbons. In addition, reactivity increases along the series benzene < naphthalene < anthrecene < tetracene < pentacene. This trend is identical to that of aromaticity for the five acenes. A correlation between reactivity and aromaticity is briefly rationalized with natural bond orbital (NBO) analysis and frontier molecular orbital (FMO) analysis. Furthermore, some experimental kinetics data from the literature supporting the calculated results are cited.
In this work, we theoretically study Diels-Alder reactions between cyclohexadiene and a series of... more In this work, we theoretically study Diels-Alder reactions between cyclohexadiene and a series of 2-aryl-4,6-dinitrobenzotriazole 1-oxides (5a-d). Based on various calculation methods such as SCF/6–31G* and DFT/B3LYP with the 6–31G* standard basis set, we discuss the thermodynamic possibility of these reactions. The reactions between a series of 6-nitrobenzotriazole 1-oxides(5aa 1 -ab 1 ) and cyclohexadiene are also studied.
The antioxidative potential of flavonoids was one of the earliest functions proposed for these co... more The antioxidative potential of flavonoids was one of the earliest functions proposed for these compounds. The grafting of the rootstock with the orange tree is an agronomical technique used to improve production and quality of the fruit. Ethanolic extracts of peel citrus fruit grafted on 8 rootstocks growing in Tunisia were investigated for their total flavonoids content and their antioxidant activity by radical DPPH method. IC50 (values denote the concentration of sample, which is required to scavenge50% of radical DPPH free radicals) for antioxidant activity ranged from 585.4-1095.1 μg/mL. Total flavonoids content (based on colorimetric AlCl3 method) varied from 11.44-44.34 mg Quercetin equivalent/g of dry extract. There were a correlation between the total flavonoids contents and antioxidant activity of peel extracts (r=-0.8654).
HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific r... more HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.
Here a biological investigationof various extract f rom T. ramosissimum (FamilyLamiaceae), an end... more Here a biological investigationof various extract f rom T. ramosissimum (FamilyLamiaceae), an endemic species from North Africa. Several co mp nents were extracted from the aerial parts using hexane, ethyl acetate, acetone and ethanol. These extracts were then investigated for their effect on two cancer cell lines (MCF-7 and HCT-116). Cytotoxicity of these extracts was measur ed using a colorimetric MTT assay. The results showed that the component extrac ted with ethanol, was the most cytotoxic on all cancer cells tested (IC 50=6 and 17μg/ml for MCF-7 and HCT-116 cell lines, respectively). Furthermore, these extracts w ere screened for their antiinflammatory activity against 5-lipoxygenase enzyme and for their anti-Alzheimer activity against the acetylcholinesterase enzyme. A ll extracts (hexane, ethyl acetate, acetone and ethanol) showed a low inhibition level on 5-lipoxygenase enzyme, 19.1, 39.7, 40.6 and 23.76%, respectively (at 60μg/ml). I n the anti-Alzheimer activity at 60μg/m...
In this work, we theoretically study the hydrogenation reaction of disubstituted cyclopentene 1a-... more In this work, we theoretically study the hydrogenation reaction of disubstituted cyclopentene 1a-d by the (Z)1,2-diazene 2 and by (E)-1,2-diazene 2'. DFT/B3LYP calculations with 6-311G** standard basis set, explain the possibility and the stereoselectivity of these reactions. The transition states of the reaction between (Z)-1,2diazene 2 and disubstituted cyclopentene 1a-d have been calculated and discussed.
Essential oils are a mixture of various compounds that can have acted against insect pests throug... more Essential oils are a mixture of various compounds that can have acted against insect pests through complex mechanisms. Their constituents were shown to be a potent source of biological pesticides. The aims of the present study are to characterize the chemical composition and evaluate the aphidicidal activities of Tunisian Melaleuca styphelioides leaves essential oil. Fumigant and contact toxicities were determined against three major aphid infecting citrus trees: Aphis gossypi, Aphis spiraecola and Myzus persicae. The chemical composition of this oil was characterized by GC-MS. The major common compounds were caryophyllene oxide (23.42%), spathulenol (20.5%), isoaromadendrene epoxide (7.45%), ledol (5.98%), and α-pinene (3.82%).The results showed that M. styphelioides essential oil has a good fumigant and contact toxicity against the three citrus aphids tested. The highest activity was registered on A. spiraecola nymphs (LC 50 = 44.72 μL/L air for the fumigant activity and 115.93 μL/L for the contact toxicity). The adults of A. gossypii seem to be more resistant to essential oil in the contact bioassay with an LC 50 = 3660.99 μL/L. Overall, our work proposes the use of the M. styphelioides essential oil as contact and fumigant bio-insecticides against resistant citrus aphids.
Seeking to explore new local natural resources, volatile profile as well as essential oil composi... more Seeking to explore new local natural resources, volatile profile as well as essential oil compositions of Tunisian Borago officinalis L. were analyzed. The current study aims at investigating the effects of the geographic origin and the plant part (flowers, leaves, and rosettes leaves) on the volatile profile of Borago officinalis L. The aerial parts were collected from three bioclimate zones in Tunisia namely Tunis, Bizerte, and Zaghouan. The essential oils were extracted by hydro distillation. The chemical composition of the latter was determined by gas chromatography coupled to mass spectrometry. Furthermore, an experimental procedure combining solid phase microextraction and gas chromatography coupled to mass spectrometry was implemented to study the volatile profile of Borago officinalis L. It was set up to assess the influence of different plant organs obtained from various sites on the aromatic profile. Essential oil yields ranged from 0.14 ± 0.00% to 0.18 ± 0.01%. Benzenacetaldehyde was the major compound of the essential oils (7.11-9.16%). Chromatographic analysis revealed that the chemical compositions vary considerably from one region to another. The ones extracted from Bizerte and Zaghouan collections were characterized by the predominance of aldehydes (27.02% and 35.16%), followed by oxygenated monoterpenes (20.64% and 20.58%). The essential oils obtained from the third collection (Tunis) showed the predominance of oxygenated monoterpenes (27.23%), followed by aldehydes (23.93%) and oxygenated sesquiterpenes (12.22%). The aldehydes were identified as the major chemical class in the flowers' volatile compounds dominated by octanal (13.32-16.42%) as well as in the leaves where nonanal was the major one (10.49-11.55%). In the rosettes aromatic profile, the oxygenated monoterpenes were the main chemical class with a percentage ranging from 39.45 to 46.64%. A relatively high content of acids (10.15%) was exclusively determined in Zaghouan flowers' volatile profile. Principal Component Analyses and Hierarchical Clustering Analyses were pertinent tools to differentiate the volatile fractions. The findings showed a remarkable difference and significant variations in quality and quantity of the secondary metabolites.
International Symposium on Medicinal and Aromatic Plants - SIPAM2009, 2010
La valorisation des plantes aromatiques et médicinales passe obligatoirement par l'extraction de ... more La valorisation des plantes aromatiques et médicinales passe obligatoirement par l'extraction de leurs huiles essentielles. Or cette extraction est confrontée, entre autres, à la faible teneur en huile essentielle dans la matière végétale. Par conséquent, des solutions technologiques, permettant la récupération aussi complète que possible des huiles essentielles de bonne qualité, sont à rechercher même lorsqu'il s'agit du plus ancien des procédés d'extraction. En outre, si les techniques extractives ont gardé, au cours des siècles, leurs principes de base, la recherche dans ce domaine s'est orientée vers la maîtrise et l'optimisation des paramètres liés aussi bien aux particularités de la matière végétale à traiter, qu'au procédé lui-même afin d'obtenir un produit de bonne qualité et de minimiser le temps d'extraction. C'est dans ce cadre que se situe notre travail qui vise à déterminer les conditions opératoires optimales d'extraction de huile essentielle du myrte obtenues par le procédé d'hydrodistillation à l'échelle du laboratoire. L'étude a porté sur trois facteurs à savoir : la durée d'exposition de la matière végétale aux ultrasons, le rapport masse de la matière végétale/masse d'eau, et le débit de condensation. L'optimisation a été réalisée dans un premier temps par une méthode paramétrique, puis en deuxième temps selon la méthode de la planification des expériences en utilisant un plan factoriel complet 2 3 . Ce plan associé à un modèle mathématique sous forme de polynôme du premier degré, a permis de calculer la réponse moyenne, les effets des facteurs ainsi que leurs interactions. Les résultats ont montré que le rapport masse de la matière végétale/masse d'eau et le débit de condensation ont un effet significatif (en valeur absolue) sur le rendement en huiles essentielles du myrte (respectivement -0,137 et 0,095) alors que le facteur d'ultrasons a montré un effet négligeable (de l'ordre de -0,045). Le rendement en huile essentielle récupérée à partir de 50 g de feuilles de myrte est, en moyenne de 0,87%.
International Symposium on Medicinal and Aromatic Plants - SIPAM2009, 2010
During the past few decades, the need for safer means of pest management have become crucial due ... more During the past few decades, the need for safer means of pest management have become crucial due to the harmful effects of synthetic insecticides on the environment, problems related to pests' resurgence and resistance to pesticide and risk for users. Therefore, a growing interest in research concerning the possible use of plant extracts as alternatives to synthetic insecticides was developed. In this study, we report first investigations on chemical constituents and fumigant toxicity of Pistacia lentiscus L. (Anacardiacea) essential oil against 1-7 day-old adults of Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae) and Lasioderma serricorne (F.) (Coleoptera: Anobiidae). The major compounds of the essential oil determined using the GC and the GC-MS were: α-phellandrene (3.20%), α-pinene (9.48%) and limonene (19.11%). Oil amounts tested were 5 and 45 µl in each 44 ml Plexiglas bottle with capacity corresponding to concentrations 114 and 1023 µl/L air. Great differences in insect mortality were observed within insect species, oil concentrations and exposure time. The fumigant toxicity potential of P. lentiscus on L. serricorne was higher (LC 50 = 8.44 µl/L, LC 95 = 43.68 µl/L) than T. castaneum (LC 50 =28.03 µl/L, LC 95 =63.46 µl/L). The results suggested that P. lentiscus essential oil may have potential as a control agent against these two stored product beetles.
The authors have evaluated the temperature dependence of the tight-binding transfer integral betw... more The authors have evaluated the temperature dependence of the tight-binding transfer integral between neighbouring cation molecules for some representative compounds of the (TMTSF)2X and (TMTTF)2X families using their recently determined low-temperature and/or high-pressure crystallographic structures. The changes in the transverse integrals in going from the new structures to the ambient temperature and pressure structures are largest for those integrals which
Tin tetrachloride adducts of the type SnCl4·2L (L=(Me2N)3P(O) (1), (Me2N)2P(O)F (2), Me2NP(O)F2 (... more Tin tetrachloride adducts of the type SnCl4·2L (L=(Me2N)3P(O) (1), (Me2N)2P(O)F (2), Me2NP(O)F2 (3) and P(O)F3 (4)) have been theoretically studied by means of DFT geometry optimisation (B3LYP/LANL2DZ) and 119Sn chemical shift calculations (B3LYP/SV). A good correlation was found between calculated and experimental data. On going from complex 1 to 4, the SnL bond underwent considerable lengthening, while that of SnCl was shortened (SnO: 2.11 in cis-1 vs. 2.37Å in cis-4; SnCl: 2.43 in cis-1 vs. 2.37Å in cis-4). In the same way, the SnOP bond angle was found to decrease from 147° for cis-1 to 136° for cis-4. The trends are in good agreement with the calculated metal–ligand binding energies of complexes 1–4. Interestingly, the structural changes are accompanied by increased 119Sn chemical shifts towards higher frequencies as the Me2N groups in the ligand are substituted by fluorine atoms. The theoretical results showed that the use of the all-electron SV basis set for tin, together with the 6-31G∗ basis set for the other atoms could efficiently predict the 119Sn NMR chemical shifts in the complexes SnCl4·2L.
ABSTRACT In this theoretical work, we computed the equilibrium geometries and a set of rotational... more ABSTRACT In this theoretical work, we computed the equilibrium geometries and a set of rotational and vibrational spectroscopic parameters for cyano substituted 2-pyridones neutral or cationic and their tautomers (cyano 2-hydroxypyridines). We examined also the effect of tautomerism equilibrium on those systems. In our analysis, we mostly focused on the perturbations induced by the CN group on the electronic structure and on the spectroscopy of 2-pyridone / 2-hydroxypyridine block. Moreover, we investigated the pattern of their low lying electronic states at both the PBE0/aug-cc-pVDZ Density Functional Theory (DFT) and the CASSCF/aug-cc-pVTZ levels of theory. Vertical excitation spectra and both adiabatic and vertical ionization energies were performed.
Impregnation of size-selected titanium-oxo-alkoxy nanoparticles into monolithic ultraporous alumi... more Impregnation of size-selected titanium-oxo-alkoxy nanoparticles into monolithic ultraporous alumina (UPA) permits nanoparticulate photocatalytic media with an extended activity into the high-temperature range up to 1000 °C, which is explained by anatase TiO 2 phase stability due to the inhibited nanoparticles aggregation. In this Article we report on the effect of the nanoparticle polymorphism and size on the photocatalytic ethylene gas decomposition. Use of UPA supports of γ, θ, and α polymorphs, covered with silica or not, and thermal treatment at different temperatures allow modification of the nanoparticles size and crystalline composition. In all cases, the interaction between titania and UPA support is found to affect the polymorph stability. In particular, a separating layer of silica increases the temperature of the anatase-rutile transformation. The main conclusion is that anatase nanoparticles exhibit the higher activity compared to rutile and composite anatase/rutile nanoparticles. The rutile activity strongly decreases with size 2R ≥ 5 nm, while that of anatase nanoparticles does not appreciably change for sizes 5 nm ≤ 2R ≤ 10 nm. The material activity strongly decreases when rutile phase is nucleated onto the anatase one.
A systematic theoretical DFT study of the bonding between the cation Fe 3C and the anion H 2 PO 4... more A systematic theoretical DFT study of the bonding between the cation Fe 3C and the anion H 2 PO 4 K was carried out. By interesting in tetrahedral, bipyramidal and octahedral environments around the iron ion, several isomers were studied and their geometries were established in each case. Calculated infra-red spectra were also done.
The crystallographic structures under constraints of representatives salts of the title families ... more The crystallographic structures under constraints of representatives salts of the title families lead to unexpected variations of the corresponding band structures and Fermi surfaces. We discuss in this study the role of the anion size for X-=ClO4,Re04 on the transfer integrals magnitude at different temperatures. For (TMTSF)2ReO 4 at 125K, the two inequivalent dimers resulting from the anion ordering along a lead to a calculated site energy difference of 72 meV. For the same salt, it is found that in the 125K averaged structure, the interchain transfer integrals are very close to the (TMTSF)2CIO 4 ones. Thus, it would be mainly the a-axis anion ordering which prevents at low T and ambient pressure the appearance of SC in the Re04 salt.
Crystallographic structures of (TNTSF)~ PF6 at low temperature (T=4K) or under joint T and P effe... more Crystallographic structures of (TNTSF)~ PF6 at low temperature (T=4K) or under joint T and P effects (T=I.TK~ P=TXlO2fPa) have been investigated. Results are compared to those obtained at room temperature when pressure is applied up to lO×lO=KPa. Evidence is thus given of non-cumulative temperature and pressure effects on the 'rfTsF packing, The calculated transfer integrals are discussed in relation to their room temperature and ambient pressure values, Induced changes in the Fermi surface are presented, They lead to a close dependence of the nesting vector with T and/or P experimental conditions, At T=I,TK~ P=TxIO~IiPa, the calculated nesting vector is nearly (2k~,x/2b) pointing to a SD¥ wave vector close to (1/2,114).
The G3(MP2) method has been employed to study the 1,4-addition reactions between singlet oxygen a... more The G3(MP2) method has been employed to study the 1,4-addition reactions between singlet oxygen and five acenes, including benzene, naphthalene, anthrecene, tetracene, and pentacene. In all, nine pathways between O 2 and the five acenes have been investigated. Our calculated results indicate that all nine pathways are concerted and exothermic and that the most reactive sites on the acenes are the center ring's meso-carbons. In addition, reactivity increases along the series benzene < naphthalene < anthrecene < tetracene < pentacene. This trend is identical to that of aromaticity for the five acenes. A correlation between reactivity and aromaticity is briefly rationalized with natural bond orbital (NBO) analysis and frontier molecular orbital (FMO) analysis. Furthermore, some experimental kinetics data from the literature supporting the calculated results are cited.
In this work, we theoretically study Diels-Alder reactions between cyclohexadiene and a series of... more In this work, we theoretically study Diels-Alder reactions between cyclohexadiene and a series of 2-aryl-4,6-dinitrobenzotriazole 1-oxides (5a-d). Based on various calculation methods such as SCF/6–31G* and DFT/B3LYP with the 6–31G* standard basis set, we discuss the thermodynamic possibility of these reactions. The reactions between a series of 6-nitrobenzotriazole 1-oxides(5aa 1 -ab 1 ) and cyclohexadiene are also studied.
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Papers by M. Abderrabba