Adenine nucleobases

Figure 5) corresponding to the completely delocalized exciton over one strand of the (A) 12 (T) i2- This indicates that both eigenstates <13> and <22> which are localized on the transition associated with adenine remains localized on only one strand of the (A) 12 (T) 12 composed of adenine nucleobases. 

Figure 19. Metalated cyclic nucleobase quartet containing dianionic guanine and monoanionic adenine nucleobases. [Reprinted with permission from M. S. Liith, E. Freisinger, F. Glahe, and B. Fippert, Inorg. Chem., 37, 5044 (1998). Copyright American Chemical Society.]...

The binding of first-row transition metal monocations (Sc -Cu ) to N7 of guanine and N7 or N3 of adenine nucleobases was studied using the DFT approach with B3LYP functional. The electrostatic character of these interactions is mainly represented by metal-ligand repulsion. 

Sponer (Sponer et al. 1999) explored metalation of the exocyclic amino group of cytosine and adenine nucleobases by Pt(II) and Hg(II) complexes. Metalation induces protonation of the N3 site of cytosine and N1 atom of adenine. Hence, it causes a proton shift from an exocyclic to... 

Noguera, M., Branchadell, V., Constantino, E., Rios-Font, R., Sodupe, M., 8c Rodriguez-Santiago, L. (2007). On the bonding of first-row transition metal cations to guanine and adenine nucleobases. The Journal of Physical Chemistry A, 111, 9823. 

Sponer, J. E., Leszczynski, J., Glahe, E., Lippert, B., Sponer, J. (2001). Protonation of platinated adenine nucleobases. Gas phase vs condensed phase picture. Inorganic Chemistry, 40, 3269. 

FIGURE 2. Some of the noncovalent interactions present in adenine nucleobase. 

In the zigzag polymeric chains of compounds [M(p-ox)(H20)(7/7-ade-KA )] 2(9i/-ade) (H20) (M° = Co, Zn), the adenine nucleobase binds to the metal centres through the less basic pyrimidinic N3 atom (Fig. 10) in contrast to what occurs in the previously described purine compounds where the organic ligands are coordinated through the imidazole N9 atom. 

The different coordination sites of the adenine nucleobase generate a markedly different topology of the polymerie ehains, relative to the purine complexes. The coordinated adenine molecules are almost perpendicular to the metal-oxalato framework instead of being arranged along the growing axis of the polymeric chain like in the purine complexes. This feature results in the presence of bulkier chains, which leads to a less effective packing with crystallization water molecules and noncoordinated adenine molecules inserted between the chains. 

To verify the feasible stabilization of noncanonical forms of the protonated adenine nucleobase, we extended our B3LYP/6-31G(d) calculations to the study of the tautomeric forms of isolated cations on a water-simulated dielectric medium and including different metal-oxalato surroundings simulating those experimentally found in the eompoimds. 

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