Towards an unified chemical model of secondary bonding.

The concept of secondary bond covers a wide range of non-covalent interactions involving an acceptor (or electrophilic) molecule and an electron donor (or nucleophilic) one. It involves triel, tetrel, pnictogen, chalcogen, halogen, and aerogen bonds as well as hydrogen bonds. Such interactions yield complexes in which the internuclear distance of the electrophilic and nucleophilic centers is intermediate between the sums of the covalent and van der Waals radii of these atoms.

Hydrogen bonding and delocalization in the ELF analysis approach.

Delocalization of the electron density in the proton donor fragment has been studied for 21 complexes, A-HB (A = F, Cl; B = Ne, Ar, CO, N, FH, ClH, HO, PH, NH, Cl, F, covering the whole range of hydrogen bond strength. The proton donor and proton acceptor fragments are defined by a minimum variance principle achieved by the ELF partition. It is shown that the variance of the proton donor population as well as the charge transfer between the fragments calculated from the ELF partition is always smaller than that evaluated within the QTAIM framework.

Polarised IR and Raman spectra of the gamma-glycine single crystal.

Complete (full) set of the polarised IR and Raman spectra for the gamma-glycine single crystal at room temperature are presented. The polarised IR spectra were measured by the specular reflection method and the spectra of the imaginary parts of the refractive indices were computed by Kramers-Kronig transformation. The polarised properties of the bands are discussed with respect to the normal coordinate analysis (literature data) and diffraction crystal data (oriented gas model approximation).

Chronic liver and renal diseases differently affect structure of human serum albumin.

Human serum albumin (HSA) binding with endogenous metabolites and drugs is substantially decreased in chronic renal and liver diseases. To test the hypothesis that the decreased binding ability is caused by conformational changes of the protein, we analyzed infrared and Raman spectra of HSA isolated from healthy donors and patients with chronic uremia and liver cirrhosis. Uremia did not affect the secondary structure of HSA but modified the environment of its Asp/Glu residues.