Experimental matrix isolation and theoretical ab initio HF/6-31G(d, p) studies of infrared spectra of purine, adenine and 2-chloroadenine

Elementary Molecular Mechanisms of the Spontaneous Point Mutations in DNA: A Novel Quantum-Chemical Insight into the Classical Understanding

“…In all of these studies, it was suggested that the 9H amino tautomer of Ade is the dominant contributor to the spectra. The experimental results agree closely with calculations at different levels of theory and consistently show the 9H amino tautomer to be the most stable one (Brovarets' & Hovorun, 2011b;Hanus et al, 2004;Fonseca Guerra et al, 2006;Kwiatkowski & Leszczynski, 1992;Norinder, 1987;Nowak et al, 1989bNowak et al, , 1991Nowak et al, , 1994aNowak et al, , 1994bNowak et al, , 1996Sabio et al, 1990;Saha et al, 2006;Sygula & Buda, 1983;Wiorkiewicz-Kuczera & Karplus, 1990).…”

“…Some of the first IR spectra of Ade recorded in low-temperature inert gas matrices in the 400 to 4000 cm -1 range date back to 1985 (Stepanian et al, 1985). This study was extended by comparing the experimental spectra with calculated IR frequencies at different levels of theory (Brovarets' & Hovorun, 2011b;Nowak et al, 1989bNowak et al, , 1991Nowak et al, , 1994aNowak et al, , 1994bNowak et al, , 1996. It was concluded that the absorption of Ade was due to its 9H tautomer.…”

“…Furthermore, the various tautomeric forms of Ade have been under substantial scrutiny (Hanus et al, 2004;Kwiatkowski & Leszczynski, 1992;Laxer et al, 2001;Mishra et al, 2000;Nowak et al, 1989bNowak et al, , 1991Nowak et al, , 1994aNowak et al, , 1994bNowak et al, , 1996Plützer et al, 2001;Salter & Chaban, 2002), because of their proposed role in mutagenic and carcinogenic processes (Danilov et al, 2005;Harris et al, 2003;Topal & Fresco, 1976). Some of the first IR spectra of Ade recorded in low-temperature inert gas matrices in the 400 to 4000 cm -1 range date back to 1985 (Stepanian et al, 1985).…”

Ab initio Hartree–Fock/6‐31G** calculation on 9‐β‐D‐arabinofuranosyladenine‐5′‐monophosphate molecule: Application to the analysis of its IR and Raman spectra

“…17,19 The band at 919 cm Ϫ1 is due to sugar vibrations (mainly CC stretches) that are coupled with vibrations of the phosphate group. The POOЈ 5 bond stretching contributes to the bands at 784 (47%) 64 and 792 cm Ϫ1 (8%), the latter being mainly due to out of plane bends of the base, in agreement with the results for adenosine. 21 At 729 cm Ϫ1 a strong Raman band appears, which is attributed to different CC and CN stretches of the base.…”

Theoretical studies of force fields and IR spectra of isocytosine

“…In this study, the torsional mode of the NH group, using 2 the optimized scale factors transferred from formamide, is theoretically predicted to be at 581 cm y1 , which is in good agreement with the corresponding experimental value of 578 cm y1 . Nowak w x et al 18 presented the vibrational assignments of the IR spectrum of adenine isolated in inert-gas low-temperature matrices and concluded that the torsional vibration band of the amino in adenine was located in the region of 560᎐590 cm y1 . This result indicates that from our calculations it is likely reasonable that the band at 578 cm y1 is due to the torsion mode of the NH group in the 2 amino-oxo form of isocytosine.…”