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Author Banerjee, Pujarini ♦ Mukhopadhyay, Deb Pratim ♦ Chakraborty, Tapas
Source United States Department of Energy Office of Scientific and Technical Information
Content type Text
Language English
Subject Keyword INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY ♦ ABSORPTION SPECTROSCOPY ♦ BINDING ENERGY ♦ CHEMICAL BONDS ♦ COMPLEXES ♦ CORRELATIONS ♦ ELECTRONIC STRUCTURE ♦ FLUORINE ♦ HYDROGEN ♦ INFRARED SPECTRA ♦ MATRIX ISOLATION ♦ MONOMERS ♦ PHENOL ♦ QUANTUM MECHANICS ♦ SPECTRAL SHIFT ♦ WATER
Abstract Matrix isolation infrared spectroscopy has been used to investigate intermolecular interactions in a series of binary O–H⋯O hydrogen bonded phenol-water complexes where water is the common acceptor. The interaction at the binding site has been tuned by incorporating multiple fluorine substitutions at different aromatic ring sites of the phenol moiety. The spectral effects for the aforesaid chemical changes are manifested in the infrared spectra of the complexes as systematic increase in spectral shift of the phenolic O–H stretching fundamental (Δν{sub O–H}). While ν{sub O–H} bands of the monomers of all the fluorophenols appear within a very narrow frequency range, the increase in Δν{sub O–H} of the complexes from phenol to pentafluorophenol is very large, nearly 90%. The observed values of Δν{sub O–H} do not show a linear correlation with the total binding energies (ΔE{sub b}) of the complexes, expected according to Badger-Bauer rule. However, in the same Δν{sub O–H} vs ΔE{sub b} plot, nice linear correlations are revealed if the complexes of ortho-fluorophenols are treated separately from their meta/para-substituted analogues. The observations imply that in spite of having the same binding site (O–H⋯O) and the same chemical identities (phenolic), the complexes of ortho and non-ortho fluorophenols do not belong, from the viewpoint of detailed molecular interactions, to a homologous series. Linear correlations of Δν{sub O–H} are, however, observed with respect to the electrostatic component of ΔE{sub b} as well as the quantum mechanical charge transfer interaction energy (E{sub CT}). From quantitative viewpoint, the latter correlation along with the associated electronic structure parameters appears more satisfactory. It has also been noted that the observed Δν{sub O–H} values of the complexes display a linear relationship with the aqueous phase pK{sub a} values of the respective phenol derivatives.
ISSN 00219606
Educational Use Research
Learning Resource Type Article
Publisher Date 2015-11-28
Publisher Place United States
Journal Journal of Chemical Physics
Volume Number 143
Issue Number 20


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