Provider: ingentaconnect Database: ingentaconnect Content: application/x-research-info-systems TY - ABST AU - Dalterio, Richard AU - Huang, Xiaohua Stella AU - Yu, Kuo-Long TI - Infrared and Nuclear Magnetic Resonance Spectroscopic Study of Secondary Amide Hydrogen Bonding in Benzoyl PABA Derivatives (Retinoids) JO - Applied Spectroscopy PY - 2007-06-01T00:00:00/// VL - 61 IS - 6 SP - 603 EP - 607 KW - NMR KW - RETINOID KW - INFRARED KW - ATR KW - SECONDARY AMIDE KW - FT-IR SPECTROSCOPY KW - FOURIER TRANSFORM INFRARED SPECTROSCOPY KW - NUCLEAR MAGNETIC RESONANCE KW - HYDROGEN BOND KW - ATTENUATED TOTAL REFLECTION N2 - 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 JF–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. UR - M3 - doi:10.1366/000370207781269774 UR - ER -