The absorption and single vibronic level fluorescence spectra of some deuterated 2-aminopyridines

Hollas, J. Michael; Musa, Hamdan; Ridley, Trevor

doi:10.1016/0022-2852(84)90248-0

Cited by 11 publications

(11 citation statements)

References 6 publications

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“…These trends reflect, of course, the fact that the photon-induced changes in the geometries of 2HP and 2AP are qualitatively the same. Comparing these results to those obtained previously, we note that our ∆A, ∆B, and ∆C values for 2AP agree very well with the earlier contour studies of Hollas et al 9 We also note that significant discussion has been given, elsewhere, of the increasing tendency for ∆B to be positive in substituted benzenes, as one goes from increasingly double C-F to C-O to C-N bonds in the S 1 state. 15 2AP fits within this trend.…”

Section: Resultssupporting

confidence: 91%

“…7 In 1970, Hollas, et al 8 described the rotational band contours in the electronic spectra of three isotopomers of 2AP. Additionally, later SVL fluorescence studies of 2AP and some of its deuterated isotopomers 9 provided strong evidence for the existence of appreciable hydrogen bonding between the ring nitrogen and a hydrogen atom of the NH 2 group.…”

Section: Introductionmentioning

confidence: 99%

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High-Resolution Electronic Spectra of 2-Hydroxy and 2-Aminopyridine. Perturbing Effects of the Nitrogen Atom in the Aromatic Ring

2002

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High resolution, rotationally resolved electronic spectra of 2-hydroxypyridine (2HP) and 2-aminopyridine (2AP; at ∼277 and ∼299 nm, respectively) have been observed and fit using rigid-rotor Hamiltonians to within lifetime-limited resolutions of 170 and 120 MHz, respectively. The derived values of the rotational constants are very similar to those of phenol and aniline. However, 2HP and 2AP each exhibit inertial axis tilting, large rotations of their S 1 -S 0 electronic transition moments, and intramolecular hydrogen bonds, making them very different from their hydrocarbon analogues. Possible reasons for this behavior are discussed.

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Section: Resultssupporting

confidence: 91%

Section: Introductionmentioning

confidence: 99%

High-Resolution Electronic Spectra of 2-Hydroxy and 2-Aminopyridine. Perturbing Effects of the Nitrogen Atom in the Aromatic Ring

2002

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“…In the N−H adjacent to the aromatic nitrogen, it is 1.009 Å, whereas in the other N−H bond, it is 1.008 Å. This slight elongation of the N−H group in the neighborhood of the ring nitrogen was also reported in the literature and interpreted as a sign of a weak intramolecular H bond …”

Section: Resultssupporting

confidence: 75%

Structure and Hydrogen Bonding of Different Isomers of 2-Aminopyridine·NH₃ Studied by IR/R2PI Spectroscopy

Vaupel

Nachtigall

et al. 2004

J. Phys. Chem. A

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The electronic and vibrational spectra of the 1:1 clusters of 2-aminopyridine (2AP) with ammonia have been measured using resonant two-photon ionization (R2PI) and IR/R2PI vibrational spectroscopy. Density functional theory calculations were performed to identify structures and assign the vibrational spectra in the NH stretch region. The two lowest-energy isomers have been identified. In isomer I, which is the global minimum energy structure, ammonia forms a strong H bond with the amino group and a weak one with the aromatic nitrogen. The vibrations of the groups involved in this H bonding exhibit red shifts of 110 cm -1 for the donating amino N-H and of 69 cm -1 for the donating N-H group of ammonia. The degeneracy of the two asymmetrical vibrations of ammonia is removed in the cluster, with the corresponding bands at 3438 and 3406 cm -1 . In isomer II ammonia forms an H bond to the N-H group which points away from the aromatic nitrogen. This bond is weaker than the corresponding one in isomer I. The stretching vibration of the H bonded N-H in the amino group exhibits a red shift of 66 cm -1 , whereas the vibrations of ammonia are very similar to those of isolated ammonia. This gives evidence that ammonia is a pure H bond acceptor. The exclusiveness of these structural isomers is due to the dominant role of the proton affinity of ammonia in the H bond. The spectroscopic results are well supported by the calculations performed at the density functional level of theory. In a similar spectroscopic study of 2AP with one or two water molecules, water forms in-plane bridges between the ring nitrogen and the amino group. However, the H bond with the ring nitrogen is dominant and only one lowestenergy isomer could be found for each cluster size (Wu et al. Phys. Chem. Chem. Phys. 2004, 6, 515).

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“…As mentioned earlier, and also reported in previous studies, the 911 cm Ϫ1 band is assigned to I 2 modes in the S 1 state. [17][18][19][20][21] However, two strong, well-separated MATI peaks located at 937 and 959 cm Ϫ1 are found when the 911 cm Ϫ1 band is used as an inter-mediate state for ionization, as clearly shown in Fig. 5.…”

Section: Mode-resolved Spectra Of the 911 CM à1 (S 1 ) Band And Its Mmentioning

confidence: 86%

“…Spectroscopy of 2-aminopyridine (2AP-NH 2 ) and its deuterated analogs such as 2AP-ND 2 , 2AP-NHD, 2AP-NDH had been studied for S 0 and S 1 states by Hollas et al using absorption and dispersed fluorescence spectroscopy taken at room temperature. 17,18 Later, the Wallace group refined peak assignments for 2AP-NH 2 using jet-cooled fluorescence excitation spectroscopy. 19,20 For monodeuterated 2-aminopyridine, Hollas et al had observed spectral features due to two geometrical isomers, 2AP-NHD or 2AP-NDH, of which H or D is hydrogen-bonded to the nitrogen atom on the pyridine ring, respectively.…”

Section: Introductionmentioning

confidence: 99%

Resonant-enhanced two photon ionization and mass-analyzed threshold ionization spectroscopy of jet-cooled 2-aminopyridines (2AP–NH2,–NHD,–NDH,–ND2)

Baek

Choi

et al. 2002

The Journal of Chemical Physics

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Resonantly-enhanced two photon ionization and mass-analyzed threshold ionization ͑MATI͒ spectra of 2-aminopyridine (2AP-NH 2) and its deuterated analogs have been obtained using two-photon ͑1ϩ1Ј͒ excitation process via S 1 intermediate states for ionization. Ionization energies of 2AP-NH 2 and 2AP-ND 2 are both precisely and accurately determined to be 8.1086Ϯ0.0005 and 8.1027Ϯ0.0005 eV, respectively. Two geometrical isomers, 2AP-NHD or 2AP-NDH, of which H or D is hydrogen-bonded to the nitrogen atom on the pyridine ring, respectively, are spectroscopically well isolated using the hole-burning spectroscopy in the S 1 states. Corresponding ionization energies are thus separately determined to be 8.1067Ϯ0.0005 or 8.1048Ϯ0.0005 eV for 2AP-NHD or 2AP-NDH, respectively. Vibrational bands of 2-aminopyridine ions associated with various aromatic ring-skeletal modes are identified in the MATI spectra and appropriately assigned with the aid of ab initio calculation. All of the ring-skeletal vibrational frequencies observed in this work become slightly higher than those in the S 1 states when the molecules are ionized, consistent with the fact that the S 1-S 0 excitation is due to *transition. According to ab initio calculation, the amino group is in the molecular plane both in the S 1 and D 0 states, while it is slightly distorted in the ground state of 2-aminopyridine. Inversion modes in 2AP-ND 2 and 2AP-NDH in S 1 states are split into two bands due to their strong coupling with the other mode, which is most probably due to torsional motion of the amino group. Strong mode couplings are clearly manifested in interferencelike patterns observed in vibrational band structures of MATI spectra taken via those two bands in S 1 states as intermediate states. A new spectroscopic scheme, in which MATI signals are used for obtaining mode-resolved spectra for the intermediate state is introduced. The vibrational band at 911 cm Ϫ1 from the S 1-S 0 origin that has been previously assigned as the inversion mode of 2AP-NH 2 is found to actually consist of two closely-spaced different modes giving two clearly-resolved different Franck-Condon active modes in corresponding MATI spectra.

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The absorption and single vibronic level fluorescence spectra of some deuterated 2-aminopyridines

Cited by 11 publications

References 6 publications

High-Resolution Electronic Spectra of 2-Hydroxy and 2-Aminopyridine. Perturbing Effects of the Nitrogen Atom in the Aromatic Ring

High-Resolution Electronic Spectra of 2-Hydroxy and 2-Aminopyridine. Perturbing Effects of the Nitrogen Atom in the Aromatic Ring

Structure and Hydrogen Bonding of Different Isomers of 2-Aminopyridine·NH₃ Studied by IR/R2PI Spectroscopy

Resonant-enhanced two photon ionization and mass-analyzed threshold ionization spectroscopy of jet-cooled 2-aminopyridines (2AP–NH2,–NHD,–NDH,–ND2)

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The absorption and single vibronic level fluorescence spectra of some deuterated 2-aminopyridines

Cited by 11 publications

References 6 publications

High-Resolution Electronic Spectra of 2-Hydroxy and 2-Aminopyridine. Perturbing Effects of the Nitrogen Atom in the Aromatic Ring

High-Resolution Electronic Spectra of 2-Hydroxy and 2-Aminopyridine. Perturbing Effects of the Nitrogen Atom in the Aromatic Ring

Structure and Hydrogen Bonding of Different Isomers of 2-Aminopyridine·NH3 Studied by IR/R2PI Spectroscopy

Resonant-enhanced two photon ionization and mass-analyzed threshold ionization spectroscopy of jet-cooled 2-aminopyridines (2AP–NH2,–NHD,–NDH,–ND2)

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Structure and Hydrogen Bonding of Different Isomers of 2-Aminopyridine·NH₃ Studied by IR/R2PI Spectroscopy