Supramol. adducts of formula [N(CH2CH2)3N]-H-[OOC(CH2)nCOOH] (n = 1-7) have been obtained by mechanochem. reaction of solid dicarboxylic acids of variable chain length HOOC(CH2)nCOOH (n = 1-7) with solid 1,4-diazabicyclo[2.2.2]octane (dabco). 1H MAS and 15N CPMAS spectra have been measured to investigate the presence of intermol. hydrogen bonds between acid and base. Proton and nitrogen chem. shifts allow a distinction to be made between N+-H...O- interactions (with proton transfer) and N...H-O interactions (without proton transfer) and between strong and weak hydrogen bonds. Correlations among isotropic 1H, 15N chem. shift data and the N-O distances of the atoms involved in the hydrogen bond interaction are found. D. functional theory, applied to explore changes upon hydrogen bonding in the 1H and 15N shielding parameters, is in agreement with the exptl. values found by solid-state NMR spectroscopy. Hydrogen/deuterium H/D isotope effects on the 15N NMR chem. shifts have been also investigated.
R. Gobetto, C. Nervi, E. Valfre, M. R. Chierotti, D. Braga, L. Maini, et al. (2005). 1H MAS, 15N CPMAS, and DFT Investigation of Hydrogen-Bonded Supramolecular Adducts between the Diamine 1,4-Diazabicyclo-[2.2.2]octane and Dicarboxylic Acids of Variable Chain Length. CHEMISTRY OF MATERIALS, 17, 1457-1466 [10.1021/cm049063x].
1H MAS, 15N CPMAS, and DFT Investigation of Hydrogen-Bonded Supramolecular Adducts between the Diamine 1,4-Diazabicyclo-[2.2.2]octane and Dicarboxylic Acids of Variable Chain Length.
BRAGA, DARIO;MAINI, LUCIA;GREPIONI, FABRIZIA;
2005
Abstract
Supramol. adducts of formula [N(CH2CH2)3N]-H-[OOC(CH2)nCOOH] (n = 1-7) have been obtained by mechanochem. reaction of solid dicarboxylic acids of variable chain length HOOC(CH2)nCOOH (n = 1-7) with solid 1,4-diazabicyclo[2.2.2]octane (dabco). 1H MAS and 15N CPMAS spectra have been measured to investigate the presence of intermol. hydrogen bonds between acid and base. Proton and nitrogen chem. shifts allow a distinction to be made between N+-H...O- interactions (with proton transfer) and N...H-O interactions (without proton transfer) and between strong and weak hydrogen bonds. Correlations among isotropic 1H, 15N chem. shift data and the N-O distances of the atoms involved in the hydrogen bond interaction are found. D. functional theory, applied to explore changes upon hydrogen bonding in the 1H and 15N shielding parameters, is in agreement with the exptl. values found by solid-state NMR spectroscopy. Hydrogen/deuterium H/D isotope effects on the 15N NMR chem. shifts have been also investigated.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
