Bifurcated Chalcogen Bonds Based on One σ-Hole

Asymmetric bifurcated halogen bonds.

Halogen bonding (XB) is being extensively explored for its potential use in advanced materials and drug design. Despite significant progress in describing this interaction by theoretical and experimental methods, the chemical nature remains somewhat elusive, and it seems to vary with the selected system. In this work we present a detailed DFT analysis of three-center asymmetric halogen bond (XB...

Σ-Protocols Based on n-One-Way Group Homomorphisms

NMR detection of bifurcated hydrogen bonds in large proteins.

Hydrogen bonds play critical roles in protein structure, stability, and function. Most hydrogen bonds in proteins are derived from their crystal structures and the use of standard covalent geometry information, because the positions of hydrogen atoms are defined only in a limited number of ultrahigh-resolution crystal structures. On the other hand, NMR structure calculations rely mostly on the ...

Geometric criteria of hydrogen bonds in proteins and identification of "bifurcated" hydrogen bonds.

Empirical criteria for identification of hydrogen bonds were analyzed to produce a set of geometrically consistent criteria. For a data set of 30 structures, application of a set of purely geometrical criteria, along with exclusion of abnormal backbone conformations, also excluded a common interaction of Ser/Thr side chains with Asp/Glu side chains ([ST]/[DE] pairs). These interactions were ter...

ETS-NOCV description of σ-hole bonding

The ETS-NOCV analysis was applied to describe the σ-hole in a systematic way in a series of halogen compounds, CF3-X (X = I, Br, Cl, F), CH3I, and C(CH3)nH3-n-I (n = 1,2,3), as well as for the example germanium-based systems. GeXH3, X = F, Cl, H. Further, the ETS-NOCV analysis was used to characterize bonding with ammonia for these systems. The results show that the dominating contribution to t...