Substituent effects on the properties of the hemi-bonded complexes (XH2P···NH2Y)+ (X, Y=H, F, Cl, Br, NH2, CH3, OH)

Abstract

Ab initio calculations have been performed to study the structures, binding energies, and bonding properties of the hemi-bonded binary complexes (XH2P···NH2Y)(+) with the substituents X and Y being H, F, Cl, Br, NH2, CH3, and OH. The P···N interactions in these open-shelled systems have typical pnicogen bond characteristics but much stronger than the usual pnicogen bonds in closed-shell systems. This P···N bond can be strengthened by an electron-withdrawing substituent X or an electron-donating substituent Y, the bonding energy varies from 17 kcal mol(-1) of (CH3H2P···NH2F)(+) to 54 kcal mol(-1) of (FH2P···NH2CH3)(+). A nearly linear X-P···N arrangement is required by the pnicogen bond P···N and results in a strong hyperconjugation and charge transfer from the N lone pair to the X-P σ* antibond orbital for α spin, the P···N interaction is described as a single-electron σ bond of β spin. The AIM and NBO analyses revealed that the P···N bonds in the majority of the hemi-bonded complexes are partly covalent in nature. Graphical Abstract The P···N interactions in the open-shelled systems (XH2P···NH2Y)(+) (X, Y=H, F, Cl, Br, NH2, CH3, OH) with bonding energy of 17~54 kcal mol(-1) have typical pnicogen bond characteristics but much stronger than the usual pnicogen bonds in closed-shell systems. This P···N bond can be strengthened by an electron-withdrawing substituent X or an electron-donating substituent Y.

Super-pnicogen bonding in the radical anion of the fluorophosphine dimer

“…The radical cation has been investigated before. [34,35,36] Coupled cluster calculations describe the monocation and dication dimers 4 and 5 both as stable local minima. The first ionization requires 8.66 eV, and the second ionization another 12.95 eV, i.e.…”

Cellular Ontogeny and Hierarchy Influence the Reprogramming Efficiency of Human B Cells into Induced Pluripotent Stem Cells

“…Induced pluripotent stem cells (iPSCs) hold tremendous potential to explore donor/patientspecific somatic cells for regenerative medicine, compound screening, tissue development, and disease modeling [1]. Human iPSCs have been generated from many tissues including fibroblasts, keratinocytes [2], mesenchymal stem cells [3], nasal epithelial cells [4], and several blood cell populations such as hematopoietic stem/progenitor cells (HSPCs) [5][6][7][8], T cells [8][9][10], and myeloid cells [8][9][10]. Very recently, iPSCs were generated at very low efficiency from cord blood (CB) and peripheral blood (PB) B cells representing a breakthrough advance since human B cells had been shown previously to be refractory to reprogramming into pluripotency [11].…”

A method for predicting individual residue contributions to enzyme specificity and binding-site energies, and its application to MTH1

“…Based on the structure of the complex in 3ZR0, a negative charge must exist in the assembly composed of Asp119, Asp120, and the guanine of the substrate. A precise definition of the location of this charge at one or the other of the aspartic acid residues or at the guanine group could not be made [ 26 ] because of the very strong hydrogen bonding that was present; however, once the substrate was separated from the binding site so that the guanine became neutral, the anionic site would necessarily become localized on the two Asp residues in order for the charge to be conserved.…”

“…To a large degree, much of the geometric difference in the binding site could be attributed to the consequences of the motion of residues that were not involved in binding; in general [ 26 ], this motion is both large and involves very little energy. If this motion could be reduced without compromising the integrity of the model of the binding site, then the usefulness of the model would be increased.…”