Isomer- and species-selective infrared spectroscopy of jet-cooled 7H- and 9H-2-aminopurine and 2-aminopurine·H 2O clusters

Rajeev K. Sinha, Simon Lobsiger, Samuel Leutwyler

Research output: Contribution to journalArticle

10 Citations (Scopus)

Abstract

The infrared (IR) spectra of the supersonic-jet cooled 9H- and 7H-tautomers of 2-aminopurine (2AP) and of the 9H-2-aminopurine•H 2O monohydrate clusters have been measured by mass- and species-selective IR-UV double resonance spectroscopy in the 3200-3900 cm -1 region, covering the N-H and O-H stretching vibrations. The spectra are complemented by density functional (B3LYP and PW91) and by second-order Møller-Plesset (MP2) calculations of the electronic energies and vibrational frequenciesof the respective 2AP tautomers and clusters. The 9H- and 7H-2-aminopurine tautomers were definitively identified by the shifts of their NH and NH 2 symmetric and asymmetric stretching frequencies and by comparison to the B3LYP/TZVP calculated IR spectra. The H-bond topologies of the two previously observed 9H-2-aminopurine•H 2O isomers (Sinha. R. K.; et al. J. Phys. Chem. A2011, 115, 6208) are definitively identified as the "sugar-edge" isomer A and the "trans-amino-bound" isomer B by comparing their IR spectra to the calculated frequencies and IR intensities of the cluster isomers A, B, C, and D, as well as to the IR spectrum of 9H-2AP. The sugar-edge isomer A involves N9-H•••OH 2 and HOH•••N3 hydrogen bonds and is predicted to be the most stable form. The amino-bound isomer B involves NH 2•••OH 2 and HOH•••N1 hydrogen bonds and is calculated to lie 2.5 kJ/mol above isomer A. The H-bond topology of the "cis-amino- bound" isomer C is symmetrically related to isomer B, with a hydrogen bond to the N3 of the pyrimidine group. However, it is calculated to lie 7 kJ/mol above isomer A and indeed is not observed in the supersonic jet. Isomer D involves a single H-bond to the N7 position, is predicted to be 14 kJ/mol above A and is therefore not observed.

Original languageEnglish
Pages (from-to)1129-1136
Number of pages8
JournalJournal of Physical Chemistry A
Volume116
Issue number4
DOIs
Publication statusPublished - 02-02-2012

Fingerprint

2-Aminopurine
Isomers
Infrared spectroscopy
isomers
infrared spectroscopy
Infrared radiation
tautomers
infrared spectra
Hydrogen bonds
hydrogen bonds
sugars
Sugars
Stretching
topology
Topology
Chemical bonds
pyrimidines

All Science Journal Classification (ASJC) codes

  • Physical and Theoretical Chemistry

Cite this

@article{4952c099016d4c1ab34583d596ec781b,
title = "Isomer- and species-selective infrared spectroscopy of jet-cooled 7H- and 9H-2-aminopurine and 2-aminopurine·H 2O clusters",
abstract = "The infrared (IR) spectra of the supersonic-jet cooled 9H- and 7H-tautomers of 2-aminopurine (2AP) and of the 9H-2-aminopurine•H 2O monohydrate clusters have been measured by mass- and species-selective IR-UV double resonance spectroscopy in the 3200-3900 cm -1 region, covering the N-H and O-H stretching vibrations. The spectra are complemented by density functional (B3LYP and PW91) and by second-order M{\o}ller-Plesset (MP2) calculations of the electronic energies and vibrational frequenciesof the respective 2AP tautomers and clusters. The 9H- and 7H-2-aminopurine tautomers were definitively identified by the shifts of their NH and NH 2 symmetric and asymmetric stretching frequencies and by comparison to the B3LYP/TZVP calculated IR spectra. The H-bond topologies of the two previously observed 9H-2-aminopurine•H 2O isomers (Sinha. R. K.; et al. J. Phys. Chem. A2011, 115, 6208) are definitively identified as the {"}sugar-edge{"} isomer A and the {"}trans-amino-bound{"} isomer B by comparing their IR spectra to the calculated frequencies and IR intensities of the cluster isomers A, B, C, and D, as well as to the IR spectrum of 9H-2AP. The sugar-edge isomer A involves N9-H•••OH 2 and HOH•••N3 hydrogen bonds and is predicted to be the most stable form. The amino-bound isomer B involves NH 2•••OH 2 and HOH•••N1 hydrogen bonds and is calculated to lie 2.5 kJ/mol above isomer A. The H-bond topology of the {"}cis-amino- bound{"} isomer C is symmetrically related to isomer B, with a hydrogen bond to the N3 of the pyrimidine group. However, it is calculated to lie 7 kJ/mol above isomer A and indeed is not observed in the supersonic jet. Isomer D involves a single H-bond to the N7 position, is predicted to be 14 kJ/mol above A and is therefore not observed.",
author = "Sinha, {Rajeev K.} and Simon Lobsiger and Samuel Leutwyler",
year = "2012",
month = "2",
day = "2",
doi = "10.1021/jp2077177",
language = "English",
volume = "116",
pages = "1129--1136",
journal = "Journal of Physical Chemistry A",
issn = "1089-5639",
publisher = "American Chemical Society",
number = "4",

}

Isomer- and species-selective infrared spectroscopy of jet-cooled 7H- and 9H-2-aminopurine and 2-aminopurine·H 2O clusters. / Sinha, Rajeev K.; Lobsiger, Simon; Leutwyler, Samuel.

In: Journal of Physical Chemistry A, Vol. 116, No. 4, 02.02.2012, p. 1129-1136.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Isomer- and species-selective infrared spectroscopy of jet-cooled 7H- and 9H-2-aminopurine and 2-aminopurine·H 2O clusters

AU - Sinha, Rajeev K.

AU - Lobsiger, Simon

AU - Leutwyler, Samuel

PY - 2012/2/2

Y1 - 2012/2/2

N2 - The infrared (IR) spectra of the supersonic-jet cooled 9H- and 7H-tautomers of 2-aminopurine (2AP) and of the 9H-2-aminopurine•H 2O monohydrate clusters have been measured by mass- and species-selective IR-UV double resonance spectroscopy in the 3200-3900 cm -1 region, covering the N-H and O-H stretching vibrations. The spectra are complemented by density functional (B3LYP and PW91) and by second-order Møller-Plesset (MP2) calculations of the electronic energies and vibrational frequenciesof the respective 2AP tautomers and clusters. The 9H- and 7H-2-aminopurine tautomers were definitively identified by the shifts of their NH and NH 2 symmetric and asymmetric stretching frequencies and by comparison to the B3LYP/TZVP calculated IR spectra. The H-bond topologies of the two previously observed 9H-2-aminopurine•H 2O isomers (Sinha. R. K.; et al. J. Phys. Chem. A2011, 115, 6208) are definitively identified as the "sugar-edge" isomer A and the "trans-amino-bound" isomer B by comparing their IR spectra to the calculated frequencies and IR intensities of the cluster isomers A, B, C, and D, as well as to the IR spectrum of 9H-2AP. The sugar-edge isomer A involves N9-H•••OH 2 and HOH•••N3 hydrogen bonds and is predicted to be the most stable form. The amino-bound isomer B involves NH 2•••OH 2 and HOH•••N1 hydrogen bonds and is calculated to lie 2.5 kJ/mol above isomer A. The H-bond topology of the "cis-amino- bound" isomer C is symmetrically related to isomer B, with a hydrogen bond to the N3 of the pyrimidine group. However, it is calculated to lie 7 kJ/mol above isomer A and indeed is not observed in the supersonic jet. Isomer D involves a single H-bond to the N7 position, is predicted to be 14 kJ/mol above A and is therefore not observed.

AB - The infrared (IR) spectra of the supersonic-jet cooled 9H- and 7H-tautomers of 2-aminopurine (2AP) and of the 9H-2-aminopurine•H 2O monohydrate clusters have been measured by mass- and species-selective IR-UV double resonance spectroscopy in the 3200-3900 cm -1 region, covering the N-H and O-H stretching vibrations. The spectra are complemented by density functional (B3LYP and PW91) and by second-order Møller-Plesset (MP2) calculations of the electronic energies and vibrational frequenciesof the respective 2AP tautomers and clusters. The 9H- and 7H-2-aminopurine tautomers were definitively identified by the shifts of their NH and NH 2 symmetric and asymmetric stretching frequencies and by comparison to the B3LYP/TZVP calculated IR spectra. The H-bond topologies of the two previously observed 9H-2-aminopurine•H 2O isomers (Sinha. R. K.; et al. J. Phys. Chem. A2011, 115, 6208) are definitively identified as the "sugar-edge" isomer A and the "trans-amino-bound" isomer B by comparing their IR spectra to the calculated frequencies and IR intensities of the cluster isomers A, B, C, and D, as well as to the IR spectrum of 9H-2AP. The sugar-edge isomer A involves N9-H•••OH 2 and HOH•••N3 hydrogen bonds and is predicted to be the most stable form. The amino-bound isomer B involves NH 2•••OH 2 and HOH•••N1 hydrogen bonds and is calculated to lie 2.5 kJ/mol above isomer A. The H-bond topology of the "cis-amino- bound" isomer C is symmetrically related to isomer B, with a hydrogen bond to the N3 of the pyrimidine group. However, it is calculated to lie 7 kJ/mol above isomer A and indeed is not observed in the supersonic jet. Isomer D involves a single H-bond to the N7 position, is predicted to be 14 kJ/mol above A and is therefore not observed.

UR - http://www.scopus.com/inward/record.url?scp=84856527808&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=84856527808&partnerID=8YFLogxK

U2 - 10.1021/jp2077177

DO - 10.1021/jp2077177

M3 - Article

VL - 116

SP - 1129

EP - 1136

JO - Journal of Physical Chemistry A

JF - Journal of Physical Chemistry A

SN - 1089-5639

IS - 4

ER -