Katarzyna Chruszcz-Lipska

Experimental (FT-IR and FT-RS) and theoretical (QC-DFT) studies of vibrational modes and molecular structure of new low-temperature phases of [Ru(NH3)6](BF4)3 and [Ru(NH3)6](ClO4)3

Vibrational spectra of [Ru(NH(3))(6)](BF(4))(3) and [Ru(NH(3))(6)](ClO(4))(3) in their novel low-temperature solid phases were recorded using FT-IR and FT-RS. Quantum chemical calculations of molecular structure and vibrational modes were made separately for BF(4)(-),ClO(4)(-)and[Ru(NH(3))(6)](3+) ions. The harmonic vibrational frequencies and the related IR and RS bands intensities and activities, respectively, were simulated at the B3LYP/6-311+G(d) and B3LYP/LANL2TZ(f)/6-311+G(d,p) levels of the DFT. Full interpretation of the vibrational spectra has been carried out with the aid of the normal coordinate analysis. The assignments of the vibrational modes were based on the potential energy distribution data, using the MOLVIB program. The calculated Ru-N stretching frequencies are too low, in comparison to experiment, which indicates that B3LYP method underestimates the Ru-N bond strength. Some values of calculated and measured (obtained from X-ray) bond lengths and angles were also compared. Conclusions about possible interactions inside and between the complex ions were drawn.

Raman Optical Activity of Biological Samples

In this Chapter, the fundamentals and instrumentation of vibrational Raman optical activity are briefly presented. Next, we describe selected examples of successful applications of computational approaches to the analysis of ROA spectra of biomolecules showing that such calculations are an important aspect of this incisive structural technique.

(-)-R-mevalonolactone studied by ROA and SERS spectroscopy.

Here we present for the first time the experimental and theoretical (DFT/B3LYP/6-311++G**) Raman optical activity (ROA) spectra of (-)-R-mevalonic acid as the δ-lactone form in neat liquid and in the aqueous solution. Quantum chemical calculations show the conformational diversity of (-)-R-mevalonolactone originated from small energy differences between the various conformation of the six-membered ring and the arrangement of the hydroxyl group. According to calculations, the investigated compound takes predominantly the chair conformation with the hydroxyl group in axial position, but the contribution of the other chair and boat conformers in the equilibrium at room temperature is not negligible. Additionally, we present normal Raman and the surface enhanced Raman (SERS) spectra of (-)-R-mevalonolactone adsorbed on the colloidal silver.