Phosphine Oxides as Spectroscopic Halogen Bond Descriptors: IR and NMR Correlations with Interatomic Distances and Complexation Energy

An extensive series of 128 halogen-bonded complexes formed by trimethylphosphine oxide and various F-, Cl-, Br-, I- and At-containing molecules, ranging in energy from 0 to 124 kJ/mol, is studied by DFT calculations in vacuum. The results reveal correlations between R–X⋅⋅⋅O=PMe3 halogen bond energy ΔE, X⋅⋅⋅O distance r, halogen’s σ-hole size, QTAIM parameters at halogen bond critical point and changes of spectroscopic parameters of phosphine oxide upon complexation, such as 31P NMR chemical shift, ΔδP, and P=O stretching frequency, Δν. Some of the correlations are halogen-specific, i.e., different for F, Cl, Br, I and At, such as ΔE(r), while others are general, i.e., fulfilled for the whole set of complexes at once, such as ΔE(ΔδP). The proposed correlations could be used to estimate the halogen bond properties in disordered media (liquids, solutions, polymers, glasses) from the corresponding NMR and IR spectra.

Hydrogen Bond Contribution to Drug Bioavailability: cheminformatics approach

A review, based mainly on own publications, is devoted to methods of investigation of “structure-bioavailability” relationships. The first part of this review contains information about classification of hydrogen bond descriptors, original 2D hydrogen bond thermodynamic descriptors, program HYBOT, original 3D hydrogen bonding potentials, original hydrogen bond surface area descriptors. The second part includes the results of applications of the above mentioned of hydrogen bond descriptors for prediction of bioavailability components such as lipophilicity, solubility in water and in physiological fluids, absorption and blood-brain barrier permeability.