16 research outputs found
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Raman, surface-enhanced Raman, and density functional theory characterization of (diphenylphosphoryl)(pyridin-2-, -3-, and -4-yl)methanol
This work presents near-infrared Raman spectroscopy (FT-RS) and surface-enhanced Raman scattering (SERS) studies of three pyridine-α-hydroxymethyl biphenyl phosphine oxide isomers: (diphenylphosphoryl)(pyridin-2-yl)methanol (α-Py), (diphenylphosphoryl)(pyridin-3-yl)methanol (β-Py), and (diphenylphosphoryl)(pyridin-4-yl)methanol (γ-Py) adsorbed onto colloidal and roughened in oxidation–reduction cycles silver surfaces. The molecular geometries in the equilibrium state and vibrational frequencies were calculated by density functional theory (DFT) at the B3LYP 6-311G(df,p) level of theory. The results imply that the most stable structure of the investigated molecules is a dimer created by two intermolecular hydrogen bonds between the H atom of the α-hydroxyl group (in up (HOU) or down (HOD) stereo bonds position) and the O atom of tertiary phosphine oxide (═O) of the two monomers. Comparison the FT-RS spectra with the respective SERS spectra allowed us to predict the orientation of the hydroxyphosphonate derivatives of pyridine that depends upon both the position of the substituent relative to the ring N atom (in α-, β-, and γ-position, respectively) and the type of silver substrate
Adduct formed by chromium trioxide and zwitterionic quinolinic acid
Chromium trioxide forms an adduct with zwitterionic quinolinic acid. The structure of the product was found to be (quinolinium-3-
carboxylato-O)trioxidochromium(VI), determined by single-crystal X-ray diffraction methods. To evaluate the bonding properties of
the compound, its structure was optimized at the B3LYP/6-311G* level of theory. The electronic characteristics were investigated by
topological methods applied to the total charge density in various model compounds including the title compound, title compound
with a HF molecule presenting a hydrogen bonding and anionic moiety. Calculated aromaticity indices indicate that the quinolinic rings
tend to conserve their degree of aromaticity against hydrogen bonding. However, when there is hydrogen bonding involving an N-H
bond or when the quinolinium zwitterion is deprotonated, there are clear changes in the interaction between chromium trioxide and
the quinolinic moiety
Raman, Surface-Enhanced Raman, and Density Functional Theory Characterization of (Diphenylphosphoryl)(pyridin-2‑, -3‑, and -4-yl)methanol
This work presents near-infrared
Raman spectroscopy (FT-RS) and
surface-enhanced Raman scattering (SERS) studies of three pyridine-α-hydroxymethyl
biphenyl phosphine oxide isomers: (diphenylphosphoryl)(pyridin-2-yl)methanol
(α-Py), (diphenylphosphoryl)(pyridin-3-yl)methanol (β-Py),
and (diphenylphosphoryl)(pyridin-4-yl)methanol (γ-Py) adsorbed
onto colloidal and roughened in oxidation–reduction cycles
silver surfaces. The molecular geometries in the equilibrium state
and vibrational frequencies were calculated by density functional
theory (DFT) at the B3LYP 6-311G(df,p) level of theory. The results
imply that the most stable structure of the investigated molecules
is a dimer created by two intermolecular hydrogen bonds between the
H atom of the α-hydroxyl group (in up (HO<sub>U</sub>) or down
(HO<sub>D</sub>) stereo bonds position) and the O atom of tertiary
phosphine oxide (O) of the two monomers. Comparison the FT-RS
spectra with the respective SERS spectra allowed us to predict the
orientation of the hydroxyphosphonate derivatives of pyridine that
depends upon both the position of the substituent relative to the
ring N atom (in α-, β-, and γ-position, respectively)
and the type of silver substrate