The three new Au (III), Pt (II) and Pd (II) complexes with pentapeptide glycyl-glycyl-(L)-methyonyl-glycyl-glycine have been synthesized, isolated, and spectroscopically and structurally elucidated in solution and in the solid-state. Solid-state linear-dichroic infrared (IR-LD) spectroscopy of oriented colloids in a nematic liquid crystal host, (1)H- and (13)C-NMR, TGA and DSC, UV-VIS spectroscopy, EPR, ESI- and FAB- mass spectrometry and HPLC tandem mass spectrometry (HPLC-MS/MS) have been used. Quantum chemical calculations and molecular modelling were carried out in order to determine the structures and spectroscopic properties of the ligand, the newly synthesised metal complexes and their interactions with calf thymus DNA. The pentapeptide coordinates in a tetradentate manner with the metal ions via an S-atom on the methyonyl-side chain, two N-amide nitrogens, (after a deprotonation of gly(1) and gly(2) residues) and the primary NH(2) nitrogen of N(termini). The MN(3)S chromophores are distorted to near square planar geometry. Their interaction with calf thymus DNA shows the competitive N7 (G) coordination position, where the pentapeptide residues is coordinated with the metal centers in a tridentate manner through the S-atom and both N-amide centers. This interaction leads to a transfer from a distorted square planar geometry (D(4h) symmetry) to a pseudo tetrahedral (T(d) symmetry) of the metal ions with the obtained dihedral angle values of the MN(3)N7(G) chromophors within 114.67 degrees to 110.92 degrees . The isolated Au (III) complex is stable for about 1.5 months, while the stability of the Au (III) complex/DNA adduct is decreased to 33 days.

A distortion of the aromatic character as a result of the N py protonation of 2-aminopyridine was established by conventional and linear-polarized IR-spectroscopy, UV-and 1 H-NMR-spectral analysis of model system 2-aminopyridinium tetrachlorocuprate (II) salt. Quantum chemical ab initio calculations are performed at MP2 and B3LYP levels of theory and 6-311 ??G** basis set in order to determine the changes in the geometrical parameters and IR-spectroscopic characteristics as a result of N py protonation. The observed crystallochromy effect is discussed as well.

Dipeptide (L)-threonyl-(L)-methionine (Thr-Met) is characterized structurally by means of a solid-state linear polarized IR- spectroscopy (IR-LD) of oriented samples as a colloidal suspension in nematic liquid crystal and quantum chemical ab initio calculations. Vibrational analysis supports the experimental data as well. The role of intermolecular hydrogen bonding on conformational behavior and spectroscopic properties of the compound, studied in solid state is determined.

A detailed experimental and theoretical UV-spectral analysis of the tautomeric forms of 3-methyl-1-phenyl pyrazol-5-one and 1,3-diphenyl pyrazol-5-one as well as of the UV-irradiated photoinduced products of the latter compound were carried out. The experimental UV-spectra were compared with the theoretical ones obtained by CIS/6-31G**. Selected geometrical parameters of the different tautomers were estimated by ab initio calculations using the RHF/6-31G** level of theory and basis set, which have also been discussed with a view to the corresponding UV-results.

The self-association of 2- and 3-(acetylamino)pyridines in a condensed phase was investigated by conventional and linear-polarized IR spectroscopy. Interpretation of spectra of the monomer and associated forms was carried out by the reducing-difference procedure. Theoretical quantum chemical calculations at the B3LYP level of theory and with 6-31±G** basis set were performed in order to obtain the electronic structure and vibrational characteristics of both compounds.