Tautomers of Adenine, Cytosine, Guanine, and Thymine
Jul 17, 2007 · The four bases of DNA can exist in at least two tautomeric forms as shown below. Adenine and cytosine (which are cyclic amidines) can exist in either amino or imino forms, and guanine, thymine, and uracil (which are cyclic amides) can …
Tautomers of cytosine and their excited electronic states: a …
We have measured the IR and UV spectra of cytosine in a low-temperature argon matrix. An attempt was made to determine the tautomeric ratios existing in the matrix, making use of the matrix-isolation IR spectrum and computed IR intensities of …
On tautomerism of the cytosine molecule - PubMed
Tautomerism of the cytosine molecule is discussed in connection with recent experimental matrix-isolation infrared spectroscopic measurements and recent ab initio calculations of relative stabilities of tautomers and of IR spectra for different tautomeric forms of the compound.
A theoretical study on cytosine tautomers in aqueous media by …
Feb 4, 2000 · The present results show the importance of electrostatic solvent effects in determining observable properties of the cytosine tautomers. The amino-oxo form (C1) is the most abundant tautomer in aqueous media while the other amino-oxo form (C4) is the most energetically favored when solvent effects are included.
Tautomerism of cytosine, cytidine, and deoxycytidine: Proton …
Altogether six tautomers of cytosine and three tautomers of cytidine and deoxycytidine are studied theoretically in the gas phase and in a microhydrated environment. Their structures are optimized at MP2/6–31 + G(d,p) level. The relative energies of the isolated and the hydrated tautomers included the correction to higher correlation energy ...
(PDF) Tautomerism of cytosine, cytidine, and deoxycytidine: …
Aug 1, 2022 · Five‐hydrated cytosine tautomeric forms of are investigated at CPCM/SCS‐MP2/6–31 + G (d,p) level to evaluate the interconversion barriers between them and to explain the coexistence,...
DFT Study on tautomerism of cytosine and its 5 ... - ResearchGate
Mar 1, 2021 · Relative stabilities of the different tautomers in the molecules of cytosine, 5-fluorocytosine (5-FC), 5-chlorocytosine (5-ClC) and 5-bromocytosine (5-BrC) calculated at the CCSD (T)/...
Photophysics of cytosine tautomers: new insights into the …
Aug 7, 2013 · A comprehensive picture of the ultrafast nonradiative decay mechanisms of three cytosine tautomers (amino-keto, imino-keto, and amino-enol forms) is revealed by high-level ab initio potential energy calculations using the multistate (MS) CASPT2 method and also by on-the-fly excited-state molecular d …
Excited State Dynamics of Cold Protonated Cytosine Tautomers ...
Protonated cytosine is chosen as a benchmark system in which the locally excited 1 ππ* state decays in the femtosecond range toward long-lived charge transfer and triplet states with lifetimes ranging from microseconds to milliseconds, respectively.
Tautomers of cytosine. In a) the keto form, in b) the enol form …
Cytosine exists primarily in three tautomers, the keto, enol and imino-forms, see Fig. 1. Since the keto tautomer is the biologically relevant one and the only one found in aqueous solution and...