توجه: محتویات این صفحه به صورت خودکار پردازش شده و مقاله‌های نویسندگانی با تشابه اسمی، همگی در بخش یکسان نمایش داده می‌شوند.
۱A computational study on AIM and NBO analyses of Cation–π interactions
نویسنده(ها): ،
اطلاعات انتشار: سومین همایش ملی فن آوری های نوین شیمی و مهندسی شیمی، سال
تعداد صفحات: ۹
Cation–π complexes between the Be2+ cation and different π–systems such as parasubstituted(H, F, and NH2) benzene derivatives have been investigated by UB3LYP method using6–311++G** basis set in the gas phase and the water solution. The Be2+ ion has shown cation–πinteraction with the aromatic motifs. The natural bond orbital (NBO) analysis and the Bader’squantum theory of atoms in molecules (AIMs) are also used to elucidate the interactioncharacteristics of the investigated complexes. The HOMA, FLU, and FLUπ indices as wellestablishedaromaticity indicators have been examined. The MEP is given the visual representationof the chemically active sites and comparative reactivity of atoms.<\div>

۲A theoretical study on H–bonded complexes of thiouracil with leucine
نویسنده(ها): ،
اطلاعات انتشار: سومین همایش ملی فن آوری های نوین شیمی و مهندسی شیمی، سال
تعداد صفحات: ۸
The structure and stability in H–bonded complexes formed from interaction betweenthiouracil (T) and ieucine(L) have been investigated using B3LYP method with 6–311++G** basissets. With tree preferential interaction sites in the vicinity of the tiouracil, and two sites in thevicinity of the leucine six cyclic complexes (TL1–6) with two intermolecular hydrogen bonds(S)OT…H–O(N)L and OL…H–N(O)T were found on the potential energy surface. Six HB complexeshave electronic interaction energies (IEs) in the range of –57.534 to–24.937 kJ\mol that show thosemonomers are stabled by hydrogen bonding formation. The most stable complex is formed via NHbond of T with CO group of L and NH bond of L with CS group of T. The topological properties ofthe electron density distributions for intermolecular bridges have been analyzed in terms of theBader theory of atoms in molecules (AIM). Natural population analysis data, the electron densityand Laplacian properties have been used to evaluate the hydrogen bonding interactions. NBO andAIM analyses confirm that the charge transfer takes place from sulfur (oxygen) lone pair to s*O(N)–H antibond. Furthermore, calculated 1H NMR chemical shifts (δH) showed that the strengthening ofhydrogen bond causes 1H chemical shift of H moves to down fields.<\div>

۳AIM and NBO analyses of cation–thymine interaction
نویسنده(ها): ،
اطلاعات انتشار: سومین همایش ملی فن آوری های نوین شیمی و مهندسی شیمی، سال
تعداد صفحات: ۸
Interaction of the most stable thymine tautomer base (T1) with Li(+), Na(+), K(+), Be(2+) and Mg(2+)was studied to explore the interaction energy (IE) of thymine with cations. All the studiedcomplexes have been optimized at the B3LYP\6–311++G** level of theory in gas phase. The moststable complexes are formed in the location of the O4 atom (T1 Mn+(II). The topological propertiesof the electron density distributions for O–M bonds have been analyzed in terms of the Bader theoryof atoms in molecules (AIM). Natural population analysis data, the electron density and Laplacianproperties, as well as, Mulliken charges have been used to evaluate the cation bonding interactions.The calculated electron density properties for T1M(n+) show that O–M bonds have closed shell andnoncovalent interactions.<\div>

۴The role of H…π interaction on calculated AIM, NBO, and NMR data
نویسنده(ها): ،
اطلاعات انتشار: سومین همایش ملی فن آوری های نوین شیمی و مهندسی شیمی، سال
تعداد صفحات: ۹
The effects of F–H…π interaction are considered where the HF acts as a proton donor anddifferent π–systemssuch as para–substituted (H, OH, and CH3) benzene derivatives act as a protonacceptor. The complexes are optimized by B3LYP method using 6–311++G** basis set in the gasphase and the water solution. In addition to geometrical parameters and binding energies,topological properties of electron charge density are calculated by atoms in molecules (AIM)method. The natural bond orbital (NBO) analysis is applied to get a more precise insight into thenature of such H…π interactions. Furthermore, the effects of interactions on NMR data and theHOMO–LUMO energieshave been used to more investigation of the studied compounds.<\div>

۵H–bonded complexes of the 5–fluorouracil anticancer drug with various six–membered cyclic nitrosamine compounds:A quantum chemical study
نویسنده(ها): ،
اطلاعات انتشار: کنفرانس بین المللی مهندسی، هنر و محیط زیست، سال
تعداد صفحات: ۱۶
We present detailed theoretical studies of the H–bonded complexes formed from interaction between 5–fluorouracil and various six–membered cyclic nitrosamine compounds. In this study, an investigation on intermolecular interactions in X–NA…5FU (X = CH2, SiH2,BH, AlH, NH, PH, O and S) complexes is carried out using density functional theory. The calculations are conducted on B3LYP\6–311++G** level of theory for optimization of geometries of complexes and monomers. Furthermore, quantum theory of ‘‘Atoms in Molecules’’ (AIM) and natural bond orbital (NBO) method are applied to analyze H–bond interactions in respective complexes. The electron density (?) and Laplacian (?2?) properties, estimated by atoms in molecules calculations, indicate that O…H bonds possess low ? and positive ?2? values that these properties are typical for closed shell interactions. In addition, the examination of H–bond in these complexes by quantum theory of NBO method supports the ab initio results. Natural population analysis data, the electron density, and Laplacian properties, as well as, the ?(C–H) and ?(N–H) frequencies of complexes, calculated at the B3LYP\6–311++G** level of theory, are used to evaluate the H–bond interactions. Several correlations between topological, geometrical and energetic parameters are also found.<\div>
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