On the Aromatic Character of the Heterocyclic Bases of DNA and RNA

Cyrański, Michał K.; Gilski, Mirosław; Jaskólski, Mariusz; Krygowski, Tadeusz M.

doi:10.1021/jo034760e

Cited by 69 publications

(69 citation statements)

References 55 publications

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“…The canonical tautomer C2 is less delocalized (HOMED8 0.79) than the C1a and C1b isomers, but it is still aromatic. Similar p-electron delocalization has been previously reported for the canonical tautomer using various measures of aromaticity [70][71][72][73]. The N1 atom in C2 taking the labile proton retains its planarity.…”

Section: Resultssupporting

confidence: 83%

DFT studies on the favored and rare tautomers of neutral and redox cytosine

Raczyńska

Sapuła²,

Zientara‐Rytter³

et al. 2015

Struct Chem

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The complete tautomeric mixture consisting of nine prototropic tautomers has been studied in the gas phase at the DFT(B3LYP)/6-311?G(d,p) level for neutral, oxidized, and reduced cytosine. Rotational isomerism of the exo -OH group and geometrical isomerism of the exo =NH group have also been considered. Tautomeric conversions possible for cytosine have been compared with those for its structural models, 4-amino-and 2-hydroxypyrimidine. Effects of intramolecular interactions between neighboring groups for cytosine are analogous to those observed for model compounds. Although they are not very strong, they are sufficient to influence tautomeric equilibria and relative stabilities of individual tautomers. One-electron oxidation and one-electron reduction change tautomeric preferences. Tautomers that are rare forms for neutral cytosine become favored ones for oxidized and reduced cytosine. Aromaticity is not the main factor that dictates the tautomeric preferences. Stability of functional groups seems to be more important than full electron delocalization.

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Section: Resultssupporting

confidence: 83%

DFT studies on the favored and rare tautomers of neutral and redox cytosine

Raczyńska

Sapuła²,

Zientara‐Rytter³

et al. 2015

Struct Chem

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“…[3,20] It has also been demonstrated that the differences in the isotropic chemical shifts between the two tautomers are very similar to the differences observed for the corresponding N7/N9 substituted compounds, [3] which enables us to use here the N-substituted adenines as model compounds for adenine tautomers. The CST data [21,22] as well as the NICS indices [23,24] have already been reported for the major N9-H tautomer of adenine.…”

Section: Introductionmentioning

confidence: 80%

Chemical Shift Tensors in Isomers of Adenine: Relation to Aromaticity of Purine Rings?

et al. 2010

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The (13)C and (15)N chemical shift tensors are measured, calculated, and compared for three N-benzyladenine isomers with an attempt to characterize differences in electron distribution in the purine ring related to the position of the substituent. Furthermore, the aromaticity of the purine rings is evaluated on the basis of nucleus-independent chemical shifts, and variations among the isomers are discussed. Both parameters indicate significant differences between the electronic properties of the N3-substituted compound and the N7/N9 pair of structures, which can be viewed more generally as the reason for the different stabilities of the individual tautomers.

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“…It follows from previous studies 28,47 that H-bonding in the guanine-cytosine (G-C) Watson-Crick base pair does not change the aromaticity of the cytosine ring (cyt1) in any significant way (HOMA = 0.7). However, intermolecular interactions of the G-C pair with metal cations can increase the aromaticity of this ring up to 0.8 HOMA unit.…”

Section: Cytosine and Their H-bonded Complexesmentioning

confidence: 97%

Metal Complexation and H-bonding Effects on Electronic Structure of Cytosine Studied in the Gas Phase

Stasyuk¹,

Szatyłowicz²,

Krygowski³

2014

Croat. Chem. Acta

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Abstract.The influence of H-bonding and complexation with cations (probed by HF, F -, Li + , Na + and K + ) on structural and π-electron changes in the six most stable cytosine tautomers has been studied in the gas phase using the B3LYP/6-311++G(2d,2p) computational level. The presence of two exo-groups (amino/imino and carbonyl/hydroxyl) in cytosine tautomers significantly increases their sensitivity to structural changes due to intra-and intermolecular interactions. These interactions induce large changes in aromaticity of the rings and in the CX (X = N, O) bond lengths of exocyclic groups. Three types of H-bonds, considering their strength, could be distinguished: (i) charge-assisted X -···HF, X = N or O, as the strongest, (ii) neutral X···HF, where X is the nitrogen atom of the ring or imino group or the keto form oxygen atom and (iii) also neutral X···HF, where X being either amino N or alternatively hydroxylic O. Hydrogen bond energy decreases approximately twice in the above listed sequence of interactions. Structural consequences of H-bonding and metal complexation have been observed not only in the immediate region of the interaction but also in other parts of the molecule (the shape of the amino group, changes in CO and CN bond lengths). Complexation of the cytosine tautomers with cations leads to monotonic changes in aromaticity in line with an increase of their ionic radii.

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On the Aromatic Character of the Heterocyclic Bases of DNA and RNA

Cited by 69 publications

References 55 publications

DFT studies on the favored and rare tautomers of neutral and redox cytosine

DFT studies on the favored and rare tautomers of neutral and redox cytosine

Chemical Shift Tensors in Isomers of Adenine: Relation to Aromaticity of Purine Rings?

Metal Complexation and H-bonding Effects on Electronic Structure of Cytosine Studied in the Gas Phase

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