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Encouraged by the excellent antiplatelet properties of novel imatinib and nilotinib analogues in our previous study and based on a fact that slight structural changes, such as the incorporation of different substituents at the final phenyl ring of imatinib and nilotinib, have a strong impact on their antiplatelet potency, two pairs of constitutional isomers of the imatinib analogues 1, 2 and 3, 4, have been designed, synthesized and evaluated for their antiplatelet characteristics. The structure geometry of the imatinib analogues 1–4 and NBO (Natural Bond Orbital) charges of the lower energy conformation each of the analogues were explored by DFT. Molecular docking studies were also performed. All compounds were less efficient in inhibiting platelet aggregation induced by ADP or TRAP‐6 in comparison with arachidonic acid (AA). Similar results were obtained for the membrane expression of P‐selectin. The most active compound was also tested to inhibit c‐Src kinase. The present study demonstrates that appropriate modifications of the imatinib structure, may confer on this molecule potent antiplatelet characteristics. [ABSTRACT FROM AUTHOR]

Density functional theory (DFT) calculations of δ(13C) and δ(1H) chemical shifts and 3J(13COO1H) coupling constants of three model hydroperoxides of the naturally occurring cis‐11‐OOH and trans‐9‐OOH isomers of oleate and 9‐cis, 11‐trans‐16‐OOH endo hydroperoxide of methyl linolenate are reported. The computational δ(OOH) for various functionals and basis sets were found to be nearly identical for the cis/trans geometric isomers. The chemical shifts of the methine CHOOH protons and carbons, on the contrary, are highly diagnostic for the identification of cis/trans geometric isomerism. The chemical shifts of the olefinic protons and carbons strongly depend on the orientation of the hydroperoxide unit relative to the double bond and, thus, of importance in conformational analysis. The results are in very good agreement with the available experimental data. For the various diastereomeric pairs of the model endo‐hydroperoxide, the strongly deshielded OOH resonances, due to the presence of an intramolecular hydrogen bond between the hydroperoxide proton and an oxygen of the endo‐peroxide ring, along with the δ(CHOOH), are highly diagnostic for identification and structure elucidation of complex erythro‐ and threo‐ diastereomeric pairs of endo‐hydroperoxides; the computational results are in very good agreement with the available experimental data. The 3J(13COO1H) coupling constants were found to be < 2 Hz for the cis–trans geometric models and < 0.5 Hz for the endo‐hydroperoxide and, thus, unimportant in stereochemical analysis. Sharp resonances of the hydroperoxide protons, with Δν1/2 < 3 Hz, are required for the successful implementation of the 1H13C heteronuclear multiple bond correlation (HMBC) technique. [ABSTRACT FROM AUTHOR]

Application of the Restricted Active Space Self‐Consistent Field Theory on the S2 excited state potential energy surface of benzene shows the existence of three minima. Of these, the first one is planar with a D6h molecular point group, while the other two have a boat type structure with an approximate C2v symmetry. All three minima have a biradicaloid structure and constitute potential candidates for new photochemical pathways on the S2 surface. A common S2/S1 Conical Intersection, which is accessible from all three S2 minima has been found which decays to the S1 potential energy surface (PES) giving benzene S1 minimum as the only photoproduct. [ABSTRACT FROM AUTHOR]