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9 results on '"Bouyacoub, Abdelatif"'

1. Synthesis of achiral rod-shaped triazolic molecules and investigation of their striped texture and propeller-patterned nematic droplets

Author

Benalloua, Souria, Saidi-Besbes, Salima, Bouyacoub, Abdelatif, and Grelet, Eric

Subjects
Condensed Matter - Soft Condensed Matter, Physics - Chemical Physics
Abstract

In this study, novel achiral mesogens containing 4,4'-biphenyl central core connected on both sides through an ester function to 1-(4-(alkyloxy)phenyl)-1H-[1,2,3]-triazolyl group have been synthesized and characterized. Different mesophases have been identified, with the appearance of both a periodic striped pattern and propeller-patterned droplets close to the transition between the nematic and the smectic-C phases. This periodic texture has been found to be independent of the geometry of the sample cell. These observations suggest a spontaneous symmetry breaking which can result either from an intrinsic enantioselective self-sorting process with a chirality synchronization mechanism, or from an extrinsic surface mechanism at the interface between the two phases.

Published
2023
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6. Reactivity of Di- tert-butyl-oxiranyllith­ium - An Ab Initio Study.

Author

Hadjadj‐Aoul, Ratiba, Bouyacoub, Abdelatif, and Volatron, François

Subjects
*REACTIVITY (Chemistry), *ANIONS, *CHEMICAL reactions, *LITHIATION, *METALATION
Abstract

The reactivity of di- tert-butyl-oxiranyllithium has been studied by means of ab initio calculations at the MP2 and CCSD(T)//MP2 levels of calculation. Six reaction pathways have been studied: three ring-opening reactions, two cyclopropanation reactions, and addition to an alkyllithium. In each case, extrema and transition states have been located and characterized at the MP2 level. For all reactions under study, effects of the solvation by one or two additional alkyllithium molecules have been considered. It is found that the cyclopropanation reactions and one ring-opening reaction are the most favorable pathways, which is in agreement with the experimental data. A comparison with the reactivity of mono- tert-butyl-oxiranyllithium (previously studied at the same level of calculations) is presented. The origin of the different reactivities of these two species mainly comes from steric effects, which are more important in the di- tert-butyl-substituted compound. Finally cyclobutanation reactions have been studied for both species. This reaction could be competitive only in the case of the di- tert-butyl species. [ABSTRACT FROM AUTHOR]

Published
2014
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8. Reactivity of Monotertbutyloxiranyllithium: A Theoretical Ab Initio Study

Author

Bouyacoub, Abdelatif, HadjadjAoul, Ratiba, and Volatron, François

Abstract

The reactivity of the lithiated tertbutyloxiranyl anion has been studied by means of ab initio calculations at the CCSDTMP2 level of theory. Four reaction paths have been studied three ringopening reactions and one addition reaction. All extrema were located and characterised. The effects of solvation by one or two MeLi molecules were studied for each reaction path by reoptimising the various extrema. It was found that the addition reaction path becomes competitive when at least two MeLi molecules are taken into account. This shows the catalytic effect of alkyllithium on this reaction path. In no case could a free carbene be characterised as a reaction intermediate. © WileyVCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008

Published
2008
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