On the origin of donor O–H bond weakening in phenol-water complexes

Banerjee, Pujarini ; Mukhopadhyay, Deb Pratim ; Chakraborty, Tapas (2015) On the origin of donor O–H bond weakening in phenol-water complexes The Journal of Chemical Physics, 143 (20). Article ID 204306. ISSN 0021-9606

Full text not available from this repository.

Official URL: http://scitation.aip.org/content/aip/journal/jcp/1...

Related URL: http://dx.doi.org/10.1063/1.4936208


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 (ΔνO–H). While νO–H bands of the monomers of all the fluorophenols appear within a very narrow frequency range, the increase in ΔνO–H of the complexes from phenol to pentafluorophenol is very large, nearly 90%. The observed values of ΔνO–H do not show a linear correlation with the total binding energies (ΔEb) of the complexes, expected according to Badger-Bauer rule. However, in the same ΔνO–H vs ΔEb 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 ΔνO–H are, however, observed with respect to the electrostatic component of ΔEb as well as the quantum mechanical charge transferinteractionenergy (ECT). From quantitative viewpoint, the latter correlation along with the associated electronic structure parameters appears more satisfactory. It has also been noted that the observed ΔνO–H values of the complexes display a linear relationship with the aqueous phase pKa values of the respective phenol derivatives.

Item Type:Article
Source:Copyright of this article belongs to American Institute of Physics.
ID Code:100279
Deposited On:07 Dec 2016 12:46
Last Modified:07 Dec 2016 12:46

Repository Staff Only: item control page