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H-Bonding And Stacking Interactions Between Chloroquine And Temozolomide, Okuma Emile Kasende, Vincent De Paul Nzuwah-Nziko, Steve Scheiner
H-Bonding And Stacking Interactions Between Chloroquine And Temozolomide, Okuma Emile Kasende, Vincent De Paul Nzuwah-Nziko, Steve Scheiner
Chemistry and Biochemistry Faculty Publications
The interactions between temozolomide and chloroquine were examined via Dispersion-Corrected Density Functional Theory and MP2 methods. Chloroquine was considered in both its lowest energy structure and in a local minimum where its aromatic system and secondary amine group are free to interact directly with temozolomide. The accessibility of these two components to intermolecular interaction makes the lowest energy dimer of this local monomer minimum competitive in total energy with that involving chloroquine’s most stable monomer geometry. In either case, the most stable heterodimer places the aromatic ring systems of the two molecules parallel and directly above one another in a …
Hydrogen Bonded And Stacked Geometries Of The Temozolomide Dimer, Okuma Emile Kasende, Jules Tshishimbi Muya, Vincent De Paul Nzuwah-Nziko, Steve Scheiner
Hydrogen Bonded And Stacked Geometries Of The Temozolomide Dimer, Okuma Emile Kasende, Jules Tshishimbi Muya, Vincent De Paul Nzuwah-Nziko, Steve Scheiner
Chemistry and Biochemistry Faculty Publications
Dispersion-corrected Density Functional Theory (DFT) and MP2 quantum chemical methods are used to examine homodimers of temozolomide (TMZ). Of the twelve dimer configurations found to be minima, the antarafacial stacked dimer is the most favored, lower in energy than coplanar dimers which are stabilized by H-bonds. The comparison between B3LYP and B3LYP-D binding energies points to dispersion as a primary factor in stabilizing the stacked geometries. CO(π)→CO(π*)charge transfers between amide groups in the global minimum are identified by NBO, as well as a pair of weak CH∙∙N H-bonds. AIM analysis of the electron density provides an alternative description which includes …
Catalysis Of The Aza-Diels-Alder Reaction By Hydrogen And Halogen Bonds, Vincent De Paul Nzuwah-Nziko, Steve Scheiner
Catalysis Of The Aza-Diels-Alder Reaction By Hydrogen And Halogen Bonds, Vincent De Paul Nzuwah-Nziko, Steve Scheiner
Chemistry and Biochemistry Faculty Publications
The combination of H2C=NH and cis-1,3-butadiene to form a six-membered ring was examined by quantum calculations. The energy barrier for this reaction is substantially lowered by the introduction of an imidazolium catalyst with either a H or halogen (X) atom in the 2-position, which acts via a H or halogen bond to the N atom of the imine, respectively. X=I has the largest effect, and Cl the smallest; Br and H are roughly equivalent. The catalyst retards the formation of the incipient N-C bond from imine to diene while simultaneously accelerating the C-C bond formation. The energy of the π* …
Comparison Of Π-Hole Tetrel Bonding With Σ-Hole Halogen Bonds In Complexes Of Xcn (X = F, Cl, Br, I) And Nh3, Steve Scheiner, Vincent De Paul Nziko
Comparison Of Π-Hole Tetrel Bonding With Σ-Hole Halogen Bonds In Complexes Of Xcn (X = F, Cl, Br, I) And Nh3, Steve Scheiner, Vincent De Paul Nziko
Chemistry and Biochemistry Faculty Publications
In addition to the standard halogen bond formed when NH3 approaches XCN (X=F,Cl,Br,I) along its molecular axis, a perpendicular approach is also possible, toward a π-hole that is present above the X-C bond. MP2/aug-cc-pVDZ calculations indicate the latter geometry is favored for X=F, and the σ-hole structure is preferred for the heavier halogens. The π-hole structure is stabilized by charge transfer from the NH3 lone pair into the π*(CN) antibonding orbital, and is characterized by a bond path from the N of NH3 to the C atom of XCN, a form of tetrel bond. The most stable …