Pyridinethiones are important ligand precursors of coordination complexes of therapeutic value. In aqueous solution, pyridinethiones can dimerize and tautomerize to the corresponding thiols. However, the tautomerism of pyridinethiones, which can impact on therapeutic performance, is yet not fully understood. To resolve this important issue, we have carried out ab initio and DFT calculations to ...

The title chiral photochromic Schiff base compound, C(21)H(19)N(3)O, was synthesized from (R)-1-phenyl-ethyl-amine and the salicylaldehyde of an azobenzene derivative. The mol-ecule corresponds to the phenol-imine tautomer, the C=N and N-C bond distances being 1.279 (3) and 1.477 (3) Å, respectively. An intra-molecular O-H⋯N hydrogen bond occurs. The diazenyl group adopts a trans form with an N...

In drug discovery, protonation states and tautomerization are easily overlooked. Through a Merck-Rutgers collaboration, this paper re-examined the initial settings and preparations for the Thermodynamic Integration (TI) calculation in AMBER Free-Energy Workflows, demonstrating the value of careful consideration of ligand protonation and tautomer state. Finally, promising results comparing AMBER...

The acidity constants Ka1 and Ka2 of 2-(5-mercapto-1,3,4-thiadiazol-2-ylthio)acetic acid have been determined both by experimental and theoretical methods. pKa computations at B3LYP/6-311+G(d,p) level of theory were carried out for the two tautomeric forms, thiol and thione, of the above-mentioned acid. Comparisons between the experimental and theoretical values led to the establishing of the m...

The crystal structure of the title compound, 4-hydr-oxy-2-pyridone, C(5)H(5)NO(2), which has been the subject of several determinations using X-rays and neutron diffraction, was first reported by Low & Wilson [Acta Cryst. (1983). C39, 1688-1690]. It has been redetermined, providing a significant increase in the precision of the derived geometric parameters. The asymmetric unit comprises a plana...