We have used the Chemical Structure DataBase (CSDB) of the NCI CADD Group, an aggregated collection of over 150 small-molecule databases totaling 103.5 million structure records, to conduct tautomerism analyses on one of the largest currently existing sets of real (i.e. not computer-generated) compounds. This analysis was carried out using calculable chemical structure identifiers developed by ...

The properties of xanthurenic acid (XAN) in ground and photoexcited states have been studied using steady-state and time-resolved optical methods as well as quantum chemistry calculations. In neutral aqueous solution and in alcohols, XAN is present in a single tautomeric form (keto form), whereas in aprotic solvents and probably in basic aqueous solutions, more than one tautomeric form is prese...

The very fast relaxation of the excited states to the ground state in DNA/RNA bases is a necessary process to ensure the photostability of DNA and its rate is highly sensitive to the tautomeric form of the bases. Protonation of the bases plays a crucial role in many biochemical and mutagenic processes and it can result in alternative tautomeric structures, thus making important the knowledge of...

Tautomeric effects in the UV-absorption of trans-urocanic acid in the gas phase are investigated by means of quantum chemical calculations of sixteen tautomers at different levels, followed by absorption cross section simulations. It is shown that several trans tautomers give significant contributions to the total spectrum and that cis tautomers should not contribute to the spectrum at room tem...

The asymmetric unit of the title co-crystal, C12H9N5O·C7H6O3, contains one mol-ecule of N6-benzoyl-adenine (BA) and one mol-ecule of 4-hy-droxy-benzoic acid (HBA). The N6-benzoyl-adenine (BA) has an N(7)-H tautomeric form with nonprotonated N-1 and N-3 atoms. This tautomeric form is stabilized by a typical intra-molecular N-H⋯O hydrogen bond between the carbonyl (C=O) group and the N(7)-H hydro...

The properties of xanthurenic acid (XAN) in ground and photoexcited states have been studied using steady-state and time-resolved optical methods as well as quantum chemistry calculations. In neutral aqueous solution and in alcohols, XAN is present in a single tautomeric form (keto form), whereas in aprotic solvents and probably in basic aqueous solutions, more than one tautomeric form is prese...