Free jet absorption millimeter wave spectrum of purine

Camináti, Walther; Maccaferri, Gianni; Favero, Paolo G.; Favero, Laura B.

doi:10.1016/0009-2614(96)00093-0

Cited by 32 publications

(30 citation statements)

References 26 publications

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“…To study the geometries of all possible individual tautomers and their energetic stabilities, quantum-chemical methods were chosen, because experimental techniques cannot give the complete information on all possible tautomers and on all possible tautomeric equilibria [7–29]. Experimental methods are able to detect solely the major tautomers.…”

Section: Resultsmentioning

confidence: 99%

“…In the absence of the water molecules, they found large barriers (≥ 60 kcal mol −1 ) for the intramolecular proton-transfer. These barriers explain the preference of one N9H tautomer in the gas phase [28, 29] and in low-temperature rare-gas matrices [22–27]. Microsolvation, particularly hydrogen bonding with water molecules, dramatically lowers the barriers (by 30–40 kcal mol −1 ) of the tautomeric conversions by the concerted multipole proton transfer mechanism.…”

Section: Resultsmentioning

confidence: 99%

“…There are only a few experimental reports, probably because of high melting point of purine (215 °C). The first direct experimental evidence that in the gas phase the N9H tautomer is the favored form, has been reported by Caminati et al [29] who used a free jet milimeter wave absorption spectrometer. The observed rotational spectrum clearly showed that the assigned rotational lines belong to the N9H tautomer.…”

Section: Introductionmentioning

confidence: 99%

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Variations of the tautomeric preferences and π-electron delocalization for the neutral and redox forms of purine when proceeding from the gas phase (DFT) to water (PCM)

Raczyńska

Kamińska

2013

J Mol Model

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Quantum-chemical calculations were performed for all possible nine neutral tautomers of purine and their oxidized and reduced forms in water {PCM//DFT(B3LYP)/6−311+G(d,p)} and compared to those in the gas phase {DFT(B3LYP)/6−311+G(d,p)}. PCM hydration influences geometries, π-electron delocalization, and relative energies of purine tautomers in different ways. Generally, the harmonic oscillator model of electron delocalization (HOMED) indices increase when proceeding from the gas phase to aequeous solution for the neutral and redox forms of purine. Their changes for the neutral and oxidized tautomers are almost parallel to the relative energies showing that aromaticity plays an important role in the tautomeric preferences. Tautomeric stabilities and tautomeric preferences vary when proceeding from the gas phase to water indicating additionally that intra- and intermolecular interactions affect tautomeric equilibria. The tautomeric mixture of neutral purine in the gas phase consists mainly of the N9H tautomer, whereas two tautomers (N9H and N7H) dominate in water. For oxidized purine, N9H is favored in the gas phase, whereas N1H in water. A gain of one electron dramatically changes the relative stabilities of the CH and NH tautomers that C6H and C8H dominate in the tautomeric mixture in the gas phase, whereas N3H in water. These variations show exceptional sensitivity of the tautomeric purine system on environment in the electron-transfer reactions.Electronic supplementary materialThe online version of this article (doi:10.1007/s00894-013-1926-5) contains supplementary material, which is available to authorized users.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Variations of the tautomeric preferences and π-electron delocalization for the neutral and redox forms of purine when proceeding from the gas phase (DFT) to water (PCM)

Raczyńska

Kamińska

2013

J Mol Model

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“…[2b] With these facts in mind, we synthesized tetrachloro-substituted perylene bisimides 1 a ± c (Scheme 1) and unsubstituted perylene bisimide 2 [12] as reference material to elucidate the effect of the bay-positioned chlorine atoms on the electron affinity, the solid-state ordering and the chargetransport properties of these materials. An enhancement of the electron affinity of perylene bisimides by four chlorine substituents was observed by cyclic voltammetry of 1 a.…”

mentioning

confidence: 99%

Conformers of Guanosines and their Vibrations in the Electronic Ground and Excited States, as Revealed by Double‐Resonance Spectroscopy and Ab Initio Calculations

et al. 2004

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“…However, microwave spectra found only the N 9 ÀH form in the gas phase. [19] The lowest excited singlet state has np* character. A vertical excitation energy of 3.76 eV [16] has been calculated by CAS-PT2 for the N 9 ÀH tautomer, and an ionization energy of 9.55 eV was measured by photoelectron spectroscopy.…”

mentioning

confidence: 99%