In the field of in silico screening, many applications do not automatically consider possible tautomeric states of molecules. However, the detection of new compound candidates might rely on correct structural description, which is important for the perfect fit toward the biologically relevant interactions. In this paper, we present a new exhaustive tautomer enumeration approach implemented by m...

A combined matrix isolation FTIR and theoretical DFT/B3LYP/6-311++G(d,p) study of the molecular structure and photochemistry of 1-(tetrazol-5-yl)ethanol [1-TE] was performed. The potential energy surface landscapes of the 1H and 2H tautomers of the compound were investigated and the theoretical results were used to help characterize the conformational mixture existing in equilibrium in the gas ...

The possibility of electron binding to the HNNH3 and H2NNH2 tautomers of hydrazine was studied at the coupled cluster level of theory with single, double, and noniterative triple excitations. The HNNH3 tautomer, with a dipole moment of 5.4 D, binds an electron by 1076 cm-1 whereas the H2NNH2 tautomer forms neither a dipolenor valence-bound anionic state. It is suggested that the HNNH3 tautomer,...

A comprehensive investigation of the pp*, np* and ps* excited states of xanthine has been performed with the CASSCF, CASPT2, CC2 and ADC(2) methods. The 7H-diketo and 9H-diketo tautomers of xanthine, which are the lowest-energy tautomers in the ground state, have been studied. Out-of-plane deformation of the purine system in the lowest pp* state as well as dissociation of the NH bonds in the lo...

A comprehensive investigation of the (1)pi pi*, (1)n pi* and (1)pi sigma* excited states of xanthine has been performed with the CASSCF, CASPT2, CC2 and ADC(2) methods. The 7H-diketo and 9H-diketo tautomers of xanthine, which are the lowest-energy tautomers in the ground state, have been studied. Out-of-plane deformation of the purine system in the lowest (1)pi pi* state as well as dissociation...

Knowledge about tautomer forms of a structure is important since, e.g., a property prediction for a molecule can yield to different results which depend on the individual tautomer. Tautomers are isomers that can be transformed to each other through chemical equilibrium reactions. In this paper the first exact Branch-and-Bound (B&B) algorithm to calculate tautomer structures is proposed. The alg...

The gas-phase acidities of adenine, 9-ethyladenine, and 3-methyladenine have been investigated for the first time, using computational and experimental methods to provide an understanding of the intrinsic reactivity of adenine. Adenine is found to have two acidic sites, with the N9 site being 19 kcal mol(-1) more acidic than the N10 site; the bracketed acidities are 333 +/- 2 and 352 +/- 4 kcal...

Deoxycitidine in solution exists as two tautomers one of which is an “uncanonical” imino one. The latter can dominate with such derivatives as 5methyl, 5-hydroxymethyland 5-formylcytosine. The imino tautomer potentially is able to form a hoosteen GC base pair. To detect such pair, it is suggested to use 1H15N NMR. Formation of GC-Hoogsteen base pair with imino tautomer of cytosine can be a reas...

This communication describes the preparation and characterization of a valence tautomer complex covalently attached to gold nanoparticles. Variable-temperature IR spectroscopy is used to determine the equilibrium thermodynamic parameters for the valence tautomerization. These results are compared with a nonsurface combined valence tautomer complex. The results show that surface confinement atte...