Building up water-wire clusters

Isomer-selective ultraviolet and infrared spectra of jet-cooled 2-aminopurine (H2O)n, n = 2 and 3

Simon Lobsiger, Rajeev K. Sinha, Samuel Leutwyler

Research output: Contribution to journalArticle

8 Citations (Scopus)

Abstract

2-Aminopurine (2AP) is an adenine analogue with a high fluorescence quantum yield in water solution, which renders it a useful real-time probe of DNA structure. We report the ultraviolet (UV) and infrared (IR) spectra of size-selected and jet-cooled 9H-2AP(H2O)n clusters with n = 2 and 3. Mass- and species-specific UV/UV holeburning spectroscopy allows to separate the UV spectra of four cluster isomers in the 31200-33000 cm -1 spectral region with electronic band origins at 31339, 31450, 31891, and 32163 cm-1. Using IR/UV depletion spectroscopy in combination with B3LYP calculated harmonic vibrational frequencies, the H-bonding topologies of two isomers of the n = 2 and of two isomers of the n = 3 cluster are identified. One n = 2 isomer (denoted 2A) forms a water dimer chain between the N9H and N3 atoms at the sugar-edge site, the other isomer (denoted 2D) binds one H2O at the sugar-edge site and the other at the trans-amino site between the N1 atom and the NH 2 group. For 2-aminopurine(H2O)3, one isomer (denoted 3A) forms an H-bonded water wire at the sugar-edge site, while isomer 3B accommodates two H2O molecules at the sugar-edge and one at the trans-amino site. The approximate second-order coupled cluster (CC2) method predicts the adiabatic S1 ← S0 transitions of 9H-2-aminopurine and six water cluster isomers with n = 1-3 in very good agreement with the experimental 000 frequencies, with differences of <0.6%. The stabilization of the S1(ππ*) state of 2-aminopurine by water clusters is highly regiospecific: Isomers with one or two H 2O molecules H-bonded in the trans-amino position induce large spectra red shifts, corresponding to 1ππ* state stabilization of 10-12 kJ/mol, while water-wire cluster solvation at the sugar-edge leads to much smaller stabilization. The evolution of the IR spectra of the water-wire clusters with n = 1-3 that are H-bonded to the sugar-edge site is discussed. Qualitatively different regions (denoted I to IV) can be attributed to the different free and H-bonded OH, NH, NH2 and OH···OH water-wire stretch vibrations.

Original languageEnglish
Pages (from-to)12410-12421
Number of pages12
JournalJournal of Physical Chemistry B
Volume117
Issue number41
DOIs
Publication statusPublished - 17-10-2013

Fingerprint

2-Aminopurine
ultraviolet spectra
Isomers
infrared spectra
isomers
wire
Wire
sugars
Infrared radiation
Sugars
Water
water
Stabilization
stabilization
Ultraviolet spectroscopy
Atoms
Hydrogen
Molecules
adenines
Solvation

All Science Journal Classification (ASJC) codes

  • Physical and Theoretical Chemistry
  • Materials Chemistry
  • Surfaces, Coatings and Films

Cite this

@article{bf842b7ee1004f8ab180578c5f86f68a,
title = "Building up water-wire clusters: Isomer-selective ultraviolet and infrared spectra of jet-cooled 2-aminopurine (H2O)n, n = 2 and 3",
abstract = "2-Aminopurine (2AP) is an adenine analogue with a high fluorescence quantum yield in water solution, which renders it a useful real-time probe of DNA structure. We report the ultraviolet (UV) and infrared (IR) spectra of size-selected and jet-cooled 9H-2AP(H2O)n clusters with n = 2 and 3. Mass- and species-specific UV/UV holeburning spectroscopy allows to separate the UV spectra of four cluster isomers in the 31200-33000 cm -1 spectral region with electronic band origins at 31339, 31450, 31891, and 32163 cm-1. Using IR/UV depletion spectroscopy in combination with B3LYP calculated harmonic vibrational frequencies, the H-bonding topologies of two isomers of the n = 2 and of two isomers of the n = 3 cluster are identified. One n = 2 isomer (denoted 2A) forms a water dimer chain between the N9H and N3 atoms at the sugar-edge site, the other isomer (denoted 2D) binds one H2O at the sugar-edge site and the other at the trans-amino site between the N1 atom and the NH 2 group. For 2-aminopurine(H2O)3, one isomer (denoted 3A) forms an H-bonded water wire at the sugar-edge site, while isomer 3B accommodates two H2O molecules at the sugar-edge and one at the trans-amino site. The approximate second-order coupled cluster (CC2) method predicts the adiabatic S1 ← S0 transitions of 9H-2-aminopurine and six water cluster isomers with n = 1-3 in very good agreement with the experimental 000 frequencies, with differences of <0.6{\%}. The stabilization of the S1(ππ*) state of 2-aminopurine by water clusters is highly regiospecific: Isomers with one or two H 2O molecules H-bonded in the trans-amino position induce large spectra red shifts, corresponding to 1ππ* state stabilization of 10-12 kJ/mol, while water-wire cluster solvation at the sugar-edge leads to much smaller stabilization. The evolution of the IR spectra of the water-wire clusters with n = 1-3 that are H-bonded to the sugar-edge site is discussed. Qualitatively different regions (denoted I to IV) can be attributed to the different free and H-bonded OH, NH, NH2 and OH···OH water-wire stretch vibrations.",
author = "Simon Lobsiger and Sinha, {Rajeev K.} and Samuel Leutwyler",
year = "2013",
month = "10",
day = "17",
doi = "10.1021/jp407127c",
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publisher = "American Chemical Society",
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}

Building up water-wire clusters : Isomer-selective ultraviolet and infrared spectra of jet-cooled 2-aminopurine (H2O)n, n = 2 and 3. / Lobsiger, Simon; Sinha, Rajeev K.; Leutwyler, Samuel.

In: Journal of Physical Chemistry B, Vol. 117, No. 41, 17.10.2013, p. 12410-12421.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Building up water-wire clusters

T2 - Isomer-selective ultraviolet and infrared spectra of jet-cooled 2-aminopurine (H2O)n, n = 2 and 3

AU - Lobsiger, Simon

AU - Sinha, Rajeev K.

AU - Leutwyler, Samuel

PY - 2013/10/17

Y1 - 2013/10/17

N2 - 2-Aminopurine (2AP) is an adenine analogue with a high fluorescence quantum yield in water solution, which renders it a useful real-time probe of DNA structure. We report the ultraviolet (UV) and infrared (IR) spectra of size-selected and jet-cooled 9H-2AP(H2O)n clusters with n = 2 and 3. Mass- and species-specific UV/UV holeburning spectroscopy allows to separate the UV spectra of four cluster isomers in the 31200-33000 cm -1 spectral region with electronic band origins at 31339, 31450, 31891, and 32163 cm-1. Using IR/UV depletion spectroscopy in combination with B3LYP calculated harmonic vibrational frequencies, the H-bonding topologies of two isomers of the n = 2 and of two isomers of the n = 3 cluster are identified. One n = 2 isomer (denoted 2A) forms a water dimer chain between the N9H and N3 atoms at the sugar-edge site, the other isomer (denoted 2D) binds one H2O at the sugar-edge site and the other at the trans-amino site between the N1 atom and the NH 2 group. For 2-aminopurine(H2O)3, one isomer (denoted 3A) forms an H-bonded water wire at the sugar-edge site, while isomer 3B accommodates two H2O molecules at the sugar-edge and one at the trans-amino site. The approximate second-order coupled cluster (CC2) method predicts the adiabatic S1 ← S0 transitions of 9H-2-aminopurine and six water cluster isomers with n = 1-3 in very good agreement with the experimental 000 frequencies, with differences of <0.6%. The stabilization of the S1(ππ*) state of 2-aminopurine by water clusters is highly regiospecific: Isomers with one or two H 2O molecules H-bonded in the trans-amino position induce large spectra red shifts, corresponding to 1ππ* state stabilization of 10-12 kJ/mol, while water-wire cluster solvation at the sugar-edge leads to much smaller stabilization. The evolution of the IR spectra of the water-wire clusters with n = 1-3 that are H-bonded to the sugar-edge site is discussed. Qualitatively different regions (denoted I to IV) can be attributed to the different free and H-bonded OH, NH, NH2 and OH···OH water-wire stretch vibrations.

AB - 2-Aminopurine (2AP) is an adenine analogue with a high fluorescence quantum yield in water solution, which renders it a useful real-time probe of DNA structure. We report the ultraviolet (UV) and infrared (IR) spectra of size-selected and jet-cooled 9H-2AP(H2O)n clusters with n = 2 and 3. Mass- and species-specific UV/UV holeburning spectroscopy allows to separate the UV spectra of four cluster isomers in the 31200-33000 cm -1 spectral region with electronic band origins at 31339, 31450, 31891, and 32163 cm-1. Using IR/UV depletion spectroscopy in combination with B3LYP calculated harmonic vibrational frequencies, the H-bonding topologies of two isomers of the n = 2 and of two isomers of the n = 3 cluster are identified. One n = 2 isomer (denoted 2A) forms a water dimer chain between the N9H and N3 atoms at the sugar-edge site, the other isomer (denoted 2D) binds one H2O at the sugar-edge site and the other at the trans-amino site between the N1 atom and the NH 2 group. For 2-aminopurine(H2O)3, one isomer (denoted 3A) forms an H-bonded water wire at the sugar-edge site, while isomer 3B accommodates two H2O molecules at the sugar-edge and one at the trans-amino site. The approximate second-order coupled cluster (CC2) method predicts the adiabatic S1 ← S0 transitions of 9H-2-aminopurine and six water cluster isomers with n = 1-3 in very good agreement with the experimental 000 frequencies, with differences of <0.6%. The stabilization of the S1(ππ*) state of 2-aminopurine by water clusters is highly regiospecific: Isomers with one or two H 2O molecules H-bonded in the trans-amino position induce large spectra red shifts, corresponding to 1ππ* state stabilization of 10-12 kJ/mol, while water-wire cluster solvation at the sugar-edge leads to much smaller stabilization. The evolution of the IR spectra of the water-wire clusters with n = 1-3 that are H-bonded to the sugar-edge site is discussed. Qualitatively different regions (denoted I to IV) can be attributed to the different free and H-bonded OH, NH, NH2 and OH···OH water-wire stretch vibrations.

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