The aminomethylation of hydroxylated isoflavones with 2-aminoethanol, 3-amino-1-propanol, 4-amino-1-butanol, and 5-amino-1-pentanol in the presence of excess formaldehyde led principally to 9-(2-hydroalkyl)-9,10-dihydro-4H,8H-chromeno[8,7-e][1,3]-oxazin-4-ones 4 and/or the tautomeric 7-hydroxy-8-(1,3-oxazepan-3-ylmethyl)-4H-chromen-4-ones 5. The ratio of these tautomers was dependent on solvent...

Herein, we first address the question posed in the title by establishing the tautomerization trajectory via the double proton transfer of the adenine·guanine (A·G) DNA base mispair formed by the canonical tautomers of the A and G bases into the A*·G* DNA base mispair, involving mutagenic tautomers, with the use of the quantum-mechanical calculations and quantum theory of atoms in molecules (QTA...

The current importance of nitrogen heterocyclic carbene (NHC) ligands in several areas of coordination chemistry and catalysis can hardly be overemphasized. The deprotonation of imidazolium salts is the prime route to NHCs; however, the study of the transformations relating imidazole and NHC ligands is still an emerging area of research. The thermodynamic preference for Nor C-coordination in im...

The study of surface adsorption and reaction is not only interesting from a scientific point of view, but also important in many application fields such as energy, environment, catalysis, corrosion, electronic device, and sensor. Theoretical calculations are essential in these studies. In this thesis, first principles studies for the structure and reaction of some important single molecules on ...

The dissociation reaction of nitrosomethane into methyl and nitric oxide and the tautomerization reactions to formaldehyde oxime, nitrone, and methoxy nitrene have been studied with the second-order multiconfigurational perturbation theory (CASPT2) by the computation of numerical energy gradients. The prevailing reactions in both the ground and the excited states are dissociations. The structur...

The polymerization of tetraazaperopyrene molecules on a Cu(111) substrate, as observed in recent scanning tunneling microscopy experiments, has been investigated in detail by first-principles calculations. Tautomerization is the first step required for the formation of molecular dimers and polymers. The substrate has been found to catalyze this tautomerization. SECTION Surfaces, Interfaces, Cat...

are taken into account also in the case when the ionizable atoms are far from each other. We also take advantage of this behavior in the case of large molecules that may have ionization sites far from each other. Proteins are typical molecules in this category. One of the most difficult issues is how the effect of tautomerization and resonance can be taken into account in pK prediction. These t...