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Quantum calculations show that replacement of the H-bonds within DNA base pairs by halogen bonds can enhance their binding to one another. 

Abstract A halobenzene molecule contains several sites that are capable of acting in an electron‐donating capacity within a H−bond. One set of such sites comprise the lone electron pairs of the halogen (X) atoms on the periphery of the ring. The π‐electron system above the ring plane can also fulfill this function in many cases. DFT calculations are applied to compare and contrast the propensity of these two site types to engage in such a H−bond within the context of mono, di, tri, tetra, and hexasubstituted halobenzenes. The X atoms chosen for study comprise the full set: F, Cl, Br, and I. It is found that even when the electrostatic potential of the X lone pair is more negative than that above the ring, it is the latter position which is the preferred binding site of HCl in most cases. This preference switches over to the X lone pair only for higher order of substitution, with n=4 or 6. This pattern is explained in large measure by the higher contribution of dispersion when the proton donor is located above the ring. 

The five-membered heteroaromatic thiazole molecule contains a number of electron-rich regions that could attract an electrophile, namely the N and S lone pairs that lie in the molecular plane, and π-system areas above the plane. 

The relationship between the strength of a halogen bond (XB) and various IR and NMR spectroscopic quantities is assessed through DFT calculations. Three different Lewis acids place a Br or I atom on a phenyl ring; each is paired with a collection of N and O bases of varying electron donor power. The weakest of the XBs display a C–X bond contraction coupled with a blue shift in the associated frequency, whereas the reverse trends occur for the stronger bonds. The best correlations with the XB interaction energy are observed with the NMR shielding of the C atom directly bonded to X and the coupling constants involving the C–X bond and the C–H/F bond that lies ortho to the X substituent, but these correlations are not accurate enough for the quantitative assessment of energy. These correlations tend to improve as the Lewis acid becomes more potent, which makes for a wider range of XB strengths. 

DFT calculations evaluate the strength of σ-hole bonds formed by ZH₃and ZMe₃(Z = N, P, As, Sb) acting as electron donor. 

Abstract The propensity of the π‐electron system lying above a polycyclic aromatic system to engage in a halogen bond is examined by DFT calculations. Prototype Lewis acid CF₃I is placed above the planes of benzene, naphthalene, anthracene, phenanthrene, naphthacene, chrysene, triphenyl, pyrene, and coronene. The I atom positions itself some 3.3–3.4 Å above the polycyclic plane, and the associated interaction energy is about 4 kcal/mol. This quantity is a little smaller for benzene, but is roughly equal for the larger polycyclics. The energy only oscillates a little as the Lewis acid slides across the face of the polycyclic, preferring regions of higher π‐electron density over minima of the electrostatic potential. The binding is dominated by dispersion which contributes half of the total interaction energy. 

Abstract The lone pair of the N atom is a common electron donor in noncovalent bonds. Quantum calculations examine how various aspects of the base on which the N is located affect the strength and other properties of complexes formed with Lewis acids FH, FBr, F₂Se, and F₃As that respectively encompass hydrogen, halogen, chalcogen, and pnicogen bonds. In most cases the halogen bond is the strongest, followed in order by chalcogen, hydrogen, and pnicogen. The noncovalent bond strength increases in the sp²³order of hybridization of N. Replacement of H substituents on the base by a methyl group or substituting N by C atom to which the base N is attached, strengthens the bond. The strongest bonds occur for trimethylamine and the weakest for N₂.