87 research outputs found

    Repurposing of approved cardiovascular drugs

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    Rotationally resolved infrared spectrum of the Li+_D2 cation complex

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    The infrared spectrum of mass selected Li +-D 2 cations is recorded in the D-D stretch region (2860-2950 cm -1) in a tandem mass spectrometer by monitoring Li + photofragments. The D-D stretch vibration of Li +-D 2 is shifted by -79 cm -1 from that of the free D 2 molecule indicating that the vibrational excitation of the D 2 subunit strengthens the effective Li +-D 2 intermolecular interaction. Around 100 rovibrational transitions, belonging to parallel K a=0-0, 1-1, and 2-2 subbands, are fitted to a Watson A-reduced Hamiltonian to yield effective molecular parameters. The infrared spectrum shows that the complex consists of a Li + ion attached to a slightly perturbed D 2 molecule with a T-shaped equilibrium configuration and a 2.035 A vibrationally averaged intermolecular separation. Comparisons are made between the spectroscopic data and data obtained from rovibrational calculations using a recent three dimensional Li +-D 2 potential energy surface [R. Martinazzo, G. Tantardini, E. Bodo, and F. Gianturco, J. Chem. Phys. 119, 11241 (2003)]

    Infrared spectra of the Li +_(H 2)n(n=1-3) cation complexes

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    The Li+–(H2)n n = 1–3 complexes are investigated through infrared spectra recorded in the H–H stretch region (3980–4120 cm−1) and through ab initio calculations at the MP2∕aug-cc-pVQZ level. The rotationally resolved H–H stretch band of Li+–H2 is centered at 4053.4 cm−1 [a −108 cm−1 shift from the Q1(0) transition of H2]. The spectrum exhibits rotational substructure consistent with the complex possessing a T-shaped equilibrium geometry, with the Li+ ion attached to a slightly perturbed H2 molecule. Around 100 rovibrational transitions belonging to parallel Ka = 0‐0, 1-1, 2-2, and 3-3 subbands are observed. The Ka = 0‐0 and 1-1 transitions are fitted by a Watson A-reduced Hamiltonian yielding effective molecular parameters. The vibrationally averaged intermolecular separation in the ground vibrational state is estimated as 2.056 Å increasing by 0.004 Å when the H2 subunit is vibrationally excited. The spectroscopic data are compared to results from rovibrational calculations using recent three dimensional Li+–H2 potential energy surfaces [ Martinazzo et al., J. Chem. Phys. 119, 11241 (2003); Kraemer and Špirko, Chem. Phys. 330, 190 (2006) ]. The H–H stretch band of Li+–(H2)2, which is centered at 4055.5 cm−1 also exhibits resolved rovibrational structure. The spectroscopic data along with ab initio calculations support a H2–Li+–H2 geometry, in which the two H2 molecules are disposed on opposite sides of the central Li+ ion. The two equivalent Li+⋯H2 bonds have approximately the same length as the intermolecular bond in Li+–H2. The Li+–(H2)3 cluster is predicted to possess a trigonal structure in which a central Li+ ion is surrounded by three equivalent H2 molecules. Its infrared spectrum features a broad unresolved band centered at 4060 cm−1

    Vibrational Spectroscopy of Small Br -

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    Rotationally resolved infrared spectrum of the Li+-D-2 cation complex

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    The infrared spectrum of mass selected Li+-D-2 cations is recorded in the D-D stretch region (2860-2950 cm(-1)) in a tandem mass spectrometer by monitoring Li+ photofragments. The D-D stretch vibration of Li+-D-2 is shifted by -79 cm(-1) from that of the free D-2 molecule indicating that the vibrational excitation of the D-2 subunit strengthens the effective Li+center dot D-2 intermolecular interaction. Around 100 rovibrational transitions, belonging to parallel K-a=0-0, 1-1, and 2-2 subbands, are fitted to a Watson A-reduced Hamiltonian to yield effective molecular parameters. The infrared spectrum shows that the complex consists of a Li+ ion attached to a slightly perturbed D-2 molecule with a T-shaped equilibrium configuration and a 2.035 A vibrationally averaged intermolecular separation. Comparisons are made between the spectroscopic data and data obtained from rovibrational calculations using a recent three dimensional Li+-D-2 potential energy surface [R. Martinazzo, G. Tantardini, E. Bodo, and F. Gianturco, J. Chem. Phys. 119, 11241 (2003)]. (c) 2006 American Institute of Physics

    ARGON PRE-DISSOCIATION INFRARED SPECTROSCOPY OF TRAPPED INTERMEDIATES IN THE O+CH4OH+CH3O- + CH4 \rightarrow OH- + CH3 REACTION

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    Author Institution: Sterling Chemistry Laboratory, Yale UniversityWe characterize trapped reaction intermediates in the O+CH4OH+CH3O- + CH4 \rightarrow OH- + CH3 ion-molecule reaction using argon predissociation spectroscopy in the 2400 to 3800 wavenumber range. This reaction is calculated to display a classic double-minimum potential surface, and the trapped complex observed here is assigned to the exit channel, OH-CH3, ion- radical isomer. This assignment is based on the observation of a sharp, strong band at 3590 wavenumbers. This band displays a progression in the bare complex, which is interpreted with the aid of ab initio calculations. Vibrational motion on this surface is calculated to be quite floppy, and the progression is due to high amplitude motion arising from a barely frustrated rotation about the H- bond to the ion

    EXPLORING THE VIBRATIONAL STRUCTURE OF THE VINYLIDENE ANION USING ARGON PREDISSOCIATION SPECTROSCOPY

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    Author Institution: Sterling Chemistry Laboratory, Yale Universtiy, PO Box 208107, New Haven, CT 06520We report Ar-mediated vibrational spectra of the vinylidene anion, a relevant intermediate in various chemical processes, and its fully deuterated form in order to characterize the vibrational energy levels present in this species. Identification of the C-H asymmetric and symmetric stretching frequencies was made and confirmed by the deuterium isotope shift. This information could then be used to clarify the origin of two higher energy peaks around 4000 and 4200 cm^-^1 in the light isotope, which occur quite close to the photodetachment threshold. Preliminary analysis indicates their assignment to combination bands involving excitation of the C=C stretch along with the C-H fundamentals. The work was then extended to include the NNO molecule as a messenger species
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