The proton affinities, gas phase basicities and adiabatic ionization energies and electron affinities of some important hydroxylamines and alkanolamines were calculated using B3LYP, CBS-Q and G4MP2 methods. Also, the B3LYP method was used to calculate vertical ionization energies and electron affinities of the molecules. The calculated ionization energies are in the range of 8-10.5 eV and they decrease as the number of carbon atoms increases. Computational results and ion mobility spectrometry study confirm that some alkanolamines lose a water molecule due to protonation at oxygen site and form cationic cyclic compounds. Effect of different substitutions on the cyclization of ethanolamine was studied theoretically.

Adsorption of CO, N₂, H₂O, O₂, H₂ and NO molecules on B₃₆ cluster was studied using density functional theory (DFT) with B3LYP functional and 6-311+G(d,p) basis set. Energies, enthalpies and Gibbs free energies of the adsorption processes were calculated. The thermodynamic data showed that the B₃₆ cluster is a good adsorbent only for CO, O₂ and NO molecules. The calculated energies of adsorption of N₂, H₂ O and H₂ on the B₃₆ cluster were positive values. CO molecule is adsorbed via the carbon atom more effectively, while the nitrogen atom of NO is adsorbed better than the oxygen atom. Also, when NO and O₂ are adsorbed synchronously via both atoms, they dissociate. The edge boron atoms of the B₃₆ cluster showed more reactivity than the inner atoms.

Structural and thermodynamic properties of 10 isomers of cyanuric acid were studied in aqueous and gas phases, employing B3LYP/6-311++G(d,p) method. The aromaticities of these isomers were evaluated using nucleus-independent chemical shift (NICS) index. The calculations showed that as the number of the ketogroups increases the stability of the isomers increases and the aromaticity decreases. Mono- and di-hydrations of the isomers did not change the stability trend, so that the tri-keto isomer was the most stable isomer amongthe hydrated and non-hydrated isomers. The activation energies (Ea) of the intramolecular proton transfers (tautomerisms) and energy barriers of H-rotations around its C-O axis in enolic isomers were calculated. The energy barriers were smaller than 45 kJ/mol for the H-rotations while the Ea values of the proton transfers were in the range of 130-210 kJ/mol. Effect of micro-hydrations on the transition state structures and the energy barriers of the tautomerisms were investigated. The mono- and di-hydrations lower the activation energies to100-130 kJ/mol and 110-145 kJ/mol, respectively.

Abstract. Structural and energetic properties of Na_n (n=1–8) nanoclusters were studied employing the B3LYP method and using 6-31+(d,p) basis set. Comparison of the calculated binding energies per atom (E_b) of the cluster shows that the Na₈ cluster with D₂d symmetry group is the most stable structure among the Na_n clusters. Adsorption of neutral and protonated forms of ammonia, methylamine, ethylamine, hydrazine, guanidine, pyridine, methanolamine, and methanimine on Na₈ cluster was studied. Interaction of the neutral Lewis bases with Na₈ was very weak such that the interaction energies were smaller than − 50 kJ mol^-1 However, the protonated bases interact with Na₈ more strongly with interaction energies generally in the range of − 90 to −350 kJ mol^-1. The protonated forms of methanolamine undergo dissociative adsorption on Na₈ with adsorption energies of about − 800 kJ mol^-1. Since the protonated bases are stabilized more than the corresponding neutral ones upon adsorption on Na₈ cluster, the basicity of the Lewis bases enhances in the presence of Na8. The calculated proton affinities of the isolated Lewis bases were smaller than 990 kJ mol ^-1 while in the presence of the Na₈ cluster, the basicity increases so that the calculated proton affinities were higher than 1000 kJ mol ^-1.