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The hybrid quantum/classical (QM/MM) calculations of the aqueous solvent effect on adenine with respect to the [super 1]H and [super 15]N NMR resonance lines and their solvent shifts are presented. The results have indicated that the proper incorporation of electrostatic effects is very important for a correct assignment of the experimental NMR resonances and that the QM/MM scheme is suitable for a reliable description for such effects.

The density functional theory (DFT) is used to study the binding of clusters of gold atoms (Au) with the guanine-cytosine (GC) and adenine-thymine (AT) Watson-Crick DNA base pairs. The analysis has shown that guanine and adenine have high affinity for Au clusters and the calculated adiabatic electron affinities (AEAs) of the GC-[Au.sub.n] complexes (n = 4, 8) are found to be much larger than those of the isolated base pairs.

An experimental and computational study of hydrogen atom adducts to adenine is conducted. The result shows that the relative free energies of adenine radicals in aqueous solution point to the C-8 adducted as the most stable tautomer, which is predicted to be the predominating product at thermal equilibrium in solution at 298 K.

The evaluation of the stabilization energies and stabilization enthalpies of the most favorable H-bonded and stacked structure of the guanine... cytosine (G...C), adenine...thymine(A...T), 9-methylguanine...1-methylcytosine (mG...mC), and 9-methyladenine...1-methylmine (mA...mT) NA base pairs is given. The convergency of the MP2 interaction energy for the present complexes is rather slow, and it is found to be essential to include the extrapolation to the complete basis set limit.

A new form of the uracil-adenine dimer anion [AU (super -)] is considered where the two monomers are connected by an excess electron suspended between them. An AU(super -) anion of this kind can be formed in the gas phase by an attachment of an adenine molecule to a dipole-bound electron of uracil.

A configurational change was predicted for the adenine-imidazole complex upon dipole-bound attachment of an excess electron to this system. The presence of the electron reverses the stability order of the two lowest energy configurations of the complex.

A density functional theory (DFT) study are performed in order to explore the influences of oxygen at the C8 position on the intramolecular proton transfer between the 6-oxo form and 6-hydro form of C8 -oxidative adenine. The 8-oxo form with the oxygen at the C8 position is found to be energetically favored by the purines.

A multiphotone ionization investigation was carried out on hydrated clusters of DNA base adenine in supersonic molecular beams. It is concluded that the change of solvent to those of less proton-donating or even proton-accepting character systematically reduces the tendency of fragmentation.

Nanosecond pulse radiolysis is used for examining the dynamics of excess electrons in duplex DNA. The results have shown that, in duplex oligonucleotides (ODNs), the spectral intermediates of G-C and A-T anions complex are formed.

Several quantum mechanical calculations are conducted to present a comparative study of the acidity, as well as the proton affinity of the damaged base 1,[N.sup.6]-ethenoadenine in the gas phase and in solution. The presence of a nonpolar environment is shown to highly enhance the acidity differences of the complex and adenine and guanine.

The high-resolution scanning tunneling microscopy (STM) used to study the self-assembly of the DNA base molecule adenine (A) revealed two coexisting distinct (homo- and heterochiral) domain of adenine formed at the liquid/solid interface. The STM findings were validated and confirmed by using ab initio density functional theory (DFT) calculations.

A study uses scanning tunneling microscopy (STM) to report well-ordered supramolecular nanopatterns formed by mixing two complementary deoxyribonucleic acid bases, adenine (A) and thymine (T), respectively, at the liquid/solid interface. Interplay between the STM findings and self-consistent charge density-functional based tight-binding (SCC-DFTB) calculation method suggests the formation of the A-T-A quartets constructed on the basis of A-T base pairing.

The molecular structure of a silver-adenine metallamacrocycle, its propensity to aggregate and its luminescent properties are investigated. The unusual coordination mode, resemblance to biological purine quartets and the presence of silver-mediated helical motifs represents an example of metal-nucleobase interaction.