Journal ArticleDOI
Non-standard base pairing and stacked structures in methyl xanthine clusters
Michael P. Callahan,Zsolt Gengeliczki,Nathan Svadlenak,Haydee Valdes,Pavel Hobza,Mattanjah S. de Vries +5 more
TLDR
In this article, the authors present resonant two-photon ionization and IR-UV double resonance spectra of methylated xanthine derivatives including 7-methylxanthine, theophylline and theobromine monomer, seeded in a supersonic jet by laser desorption.Abstract:
We present resonant two-photon ionization and IR–UV double resonance spectra of methylated xanthine derivatives including 7-methylxanthine dimer and theobromine dimer seeded in a supersonic jet by laser desorption. For 7-methylxanthine, theophylline and theobromine monomer we assign the lowest energy tautomer based on comparison with IR–UV double resonance spectra and calculated IR frequencies. For the 7-methylxanthine dimer, we observe hydrogen bonding on the N3H position suggesting 3 possible combinations, one that is reverse Watson–Crick type and two that are reverse Hoogsteen type. For the theobromine dimer, we observe a stacked structure. For trimethylxanthine dimers we infer a stacked structure as well.read more
Citations
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Excited state dynamics of DNA bases
TL;DR: In this paper, a reductionist approach to unravelling the detailed photochemistry seeks to establish intrinsic properties of individual DNA building blocks, followed by extrapolation to larger systems, to incorporate interactions between the building blocks and the role of the biomolecular environment.
Journal ArticleDOI
π-Hydrogen Bonding Wins over Conventional Hydrogen Bonding Interaction: A Jet-Cooled Study of Indole···Furan Heterodimer
TL;DR: The most significant finding of this study is the first-time observation of a N-H···π bound conformer of a dimer, which wins over a conventional hydrogen-bonded Conformer of the dimer.
Journal ArticleDOI
Electrostatic studies of π–π interaction for benzene stacking on a graphene layer
TL;DR: In this article, the authors used double charge rings and its image charges model to simulate the π-π interaction between benzene and a graphene layer, which has potential for use in predicting the interactions between aromatic molecules and graphene.
Journal ArticleDOI
Isomer selective infrared spectroscopy of supersonically cooled cis- and trans-N-phenylamides in the region from the amide band to NH stretching vibration
TL;DR: The IR spectrum of Trans-acetanilide closely resembles that of trans-formanilides, except for vibrations of the methyl group; that is, substitution of the formyl hydrogen to a methyl group has only a minor effect on the amide vibrations.
Journal ArticleDOI
Photophysics of xanthine: computational study of the radiationless decay mechanisms.
TL;DR: The observed R2PI spectrum of xanthine is assigned to the 7H-diketo tautomer, in agreement with the assignment of Callahan et al. (Phys. Chem. Phys., 2007, 9, 4587-4591).
References
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Density‐functional thermochemistry. III. The role of exact exchange
TL;DR: In this article, a semi-empirical exchange correlation functional with local spin density, gradient, and exact exchange terms was proposed. But this functional performed significantly better than previous functionals with gradient corrections only, and fits experimental atomization energies with an impressively small average absolute deviation of 2.4 kcal/mol.
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Development of the Colle-Salvetti correlation-energy formula into a functional of the electron density
TL;DR: Numerical calculations on a number of atoms, positive ions, and molecules, of both open- and closed-shell type, show that density-functional formulas for the correlation energy and correlation potential give correlation energies within a few percent.
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Self‐consistent molecular orbital methods. XX. A basis set for correlated wave functions
TL;DR: In this article, a contract Gaussian basis set (6•311G) was developed by optimizing exponents and coefficients at the Mo/ller-Plesset (MP) second-order level for the ground states of first-row atoms.
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Contracted Gaussian basis sets for molecular calculations. I. Second row atoms, Z=11–18
A. D. McLean,G. S. Chandler +1 more
TL;DR: In this article, the contracted Gaussian basis sets for molecular calculations are derived from uncontracted (12,8) and ( 12,9) sets for the neutral second row atoms, Z=11-18, and for the negative ions P−, S−, and Cl−.
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Electronic structure calculations on workstation computers: the program system turbomole
TL;DR: TURBOMOLE as discussed by the authors is a program system for SCF that takes full advantage of all discrete point group symmetries and has only modest I/O and background storage requirements.