IngentaConnect Infrared and Nuclear Magnetic Resonance Spectroscopic Study of Se...

Authors: Dalterio, Richard¹; Huang, Xiaohua Stella¹; Yu, Kuo-Long²

Source: Applied Spectroscopy, Volume 61, Issue 6, Pages 110A-122A and 571-669 (June 2007) , pp. 603-607(5)

Publisher: Society for Applied Spectroscopy

Abstract:

Attenuated total reflection (ATR) Fourier transform infrared (FT-IR) and nuclear magnetic resonance (NMR) data are used to characterize the hydrogen bonding of the secondary amide N-H group of several structurally similar benzoyl derivatives of p-aminobenzoic acid esters (retinoids) in chloroform solution. The amide N-H can form intermolecular hydrogen bonds to several proton acceptors in these molecules or it can form an intramolecular hydrogen bond to a fluorine or oxygen atom in some of the molecules. The concentration dependence of the solution N-H infrared absorption bands is used to determine the formation of intramolecular and/or intermolecular H-bonds. Proton NMR spectra were obtained from deuterated chloroform solutions and the sec-amide N-H resonance was assigned for each compound. The downfield shift in the N-H resonance is correlated to intramolecular H-bond formation. Also, the NMR spectra of fluorine-containing compounds provide J_F-H through-space coupling values. Using infrared and NMR data, the relative intramolecular hydrogen bond strengths (N-H…F or N-H…O) of the compounds are approximately ranked.

Keywords: INFRARED; NUCLEAR MAGNETIC RESONANCE; NMR; ATTENUATED TOTAL REFLECTION; ATR; FOURIER TRANSFORM INFRARED SPECTROSCOPY; FT-IR SPECTROSCOPY; HYDROGEN BOND; RETINOID; SECONDARY AMIDE

Document Type: Research article

DOI: 10.1366/000370207781269774

Affiliations: 1: Bristol-Myers Squibb Company, Pharmaceutical Research Institute, Wallingford, Connecticut 06492 2: Eli Lilly and Company, Indianapolis, Indiana 46285

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Infrared and Nuclear Magnetic Resonance Spectroscopic Study of Secondary Amide Hydrogen Bonding in Benzoyl PABA Derivatives (Retinoids)