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Quantum-mechanical calculations, at HF level, were performed to gain chemical–physical basis information on the 2,4-dinitro-toluene hydrogenation occurring over palladium catalysts. To investigate the surface characteristics of the species involved in the reaction system, simplified molecular models including small metal clusters were considered. Remarkable findings, useful to elucidate the reaction mechanism and important parameters, working in time dependent Monte-Carlo simulations of the title reaction, were obtained; inter alia: the molar standard free energies of the molecules involved in the reaction, the volume occupied by the species in solution phase and the qualitative order of the desorption activation energy values, of the nitro, amino and hydroxylamino groups of the toluene fragments interacting with the Pd surface. The molecular level interaction modes of the different toluene derivatives on Pd clusters, mimicking the catalyst surface, were visualized. The results have been discussed in terms of microscopic (energetic, structural and steric hindering) factors driving the observed macroscopic reaction.

N -diphenylmethyl-2-propenamide (NDP) was synthesised and characterised. Pharmacological in vitro tests pointed out that NDP had a cytotoxic activity on a human ovarian carcinoma comparable to that of doxorubicin. Hypothesising that this in vitro cytotoxic activity could be mainly due to intercalating interactions, between the drug and DNA fragments, ab initio calculations, at the Hartree–Fock (HF) level, were performed on the structure, and on the conformational properties of NDP, whereas its interaction with an (AC)(TG) dinucleotide triphosphate duplex (DD) was studied by the ONIOM method, at HF and PM3 level for NDP and DD, respectively. The supposed intercalation process with the DNA fragment was discussed in terms of the co-planarity of the aromatic rings present in the NDP molecule.

Quantum mechanical calculations were employed to deepen information about the basic properties of the mechanism occurring in the palladium catalytic hydrogenation involving surface hydrogen species of unsaturated hydrocarbons. Activation energy values of elementary events implicated in the whole reaction were computed by potential energy surface analyses, to determine the corresponding occurrence probabilities of the same events. Different surface hydrogen species were pointed out and their relevance in the overall surface process was discussed together with their geometrical and chemical characteristics.

Quantum mechanical calculations at HF, MP2 and DFT levels were used to rationalise the surface effects of the hydrocarbon lateral interactions occurring on single planar metal surfaces or on different adjacent surfaces during the hydrogenation on palladium catalyst. The different values of electronic charge, found in the different atoms of palladium clusters, were suggested as a possible explanation of the non-homogeneous behaviour already inferred for catalyst surface sites having non-isotropic local arrangement.

The interaction between a dinucleotide triphosphate duplex (DD), mimicking the DNA molecule, and the dimethyltin(IV) cation is studied by the semiempirical PM3 method. The results show that the interaction can occur involving the tin atom and the electron-donor centres of DD, requiring in some cases the presence of water molecules. In particular, the binding of the dimethyltin(IV) moiety with two adjacent phosphate oxygen atoms is allowed by the presence of water molecules coordinating to the tin atom. In this case the tin environment shows a geometry in agreement with 119 Sn Mossbauer and X-ray data.