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| DC Field | Value | Language |
|---|---|---|
| dc.contributor.author | Diez, E. | en |
| dc.contributor.author | Fabian, J. S. | en |
| dc.contributor.author | Gerothanassis, I. P. | en |
| dc.contributor.author | Esteban, A. L. | en |
| dc.contributor.author | Abboud, J. L. M. | en |
| dc.contributor.author | Contreras, R. H. | en |
| dc.contributor.author | deKowalewski, D. G. | en |
| dc.date.accessioned | 2015-11-24T16:47:35Z | - |
| dc.date.available | 2015-11-24T16:47:35Z | - |
| dc.identifier.issn | 1090-7807 | - |
| dc.identifier.uri | https://olympias.lib.uoi.gr/jspui/handle/123456789/9208 | - |
| dc.rights | Default Licence | - |
| dc.subject | ab-initio calculations | en |
| dc.subject | o-17 nmr-spectroscopy | en |
| dc.subject | acetyl-l-proline | en |
| dc.subject | basis-sets | en |
| dc.subject | aqueous-solution | en |
| dc.subject | hydration | en |
| dc.subject | formamide | en |
| dc.subject | peptides | en |
| dc.subject | cis | en |
| dc.subject | parameters | en |
| dc.title | Solvent effects on oxygen-17 chemical shifts in amides. Quantitative linear solvation shift relationships | en |
| heal.type | journalArticle | - |
| heal.type.en | Journal article | en |
| heal.type.el | Άρθρο Περιοδικού | el |
| heal.identifier.primary | DOI 10.1006/jmre.1996.7481 | - |
| heal.identifier.secondary | <Go to ISI>://A1997WP82000003 | - |
| heal.identifier.secondary | http://ac.els-cdn.com/S1090780796974819/1-s2.0-S1090780796974819-main.pdf?_tid=5e63a238-3247-11e3-acbe-00000aacb362&acdnat=1381476966_2163f3176903900fcb347184c535ac5d | - |
| heal.language | en | - |
| heal.access | campus | - |
| heal.recordProvider | Πανεπιστήμιο Ιωαννίνων. Σχολή Θετικών Επιστημών. Τμήμα Χημείας | el |
| heal.publicationDate | 1997 | - |
| heal.abstract | A multiple-linear-regression analysis (MLRA) has been carried out using the Kamlet-Abboud-Taft (KAT) solvatochromic parameters in order to elucidate and quantify the solvent effects on the O-17 chemical shifts of N-methylformamide (NMF), N,N-dimethylformamide (DMF), N-methylacetamide (NMA), and N,N-dimethylacetamide (DMA). The chemical shifts of the four molecules show the same dependence (in ppm) on the solvent polarity-polarizability, i.e., -22 pi*. The influence of the solvent hydrogen-bond-donor (HBD) acidities is slightly larger for the acetamides NMA and DMA, i.e., -48 alpha, than for the formamides NMF and DMF, i.e., -42 alpha. The influence of the solvent hydrogen-bond-acceptor (HBA) basicities is negligible for the nonprotic molecules DMF and DMA but significant for the protic molecules NMF and NMA, i.e., -9 beta. The effect of substituting the N-H hydrogen by a methyl group amounts to -5.9 ppm in NMF and 5.4 ppm in NMA. The effect of substituting the O=C-H hydrogen amounts to 5.5 ppm in NMF and 16.8 ppm in DMF. The model of specific hydration sites of amides by I. P. Gerothanassis and C. Vakka [J. Org. Chem. 59, 2341 (1994)] is settled in a more quantitative basis and the model by M. I. Burgar, T. F. St, Amour, and D. Fiat [J. Phys. Chem. 85, 502(1981)] is critically evaluated. O-17 hydration shifts have been calculated for formamide (FOR) by the ab initio LORG method at the 6-31G* level. For a formamide surrounded by the four in-plane molecules of water in the first hydration shell, the calculated O-17 shift change due to the four hydrogen bonds, -83.2 ppm, is smaller than the empirical hydration shift, -100 ppm. The O-17 shift change from each out-of-plane water molecule hydrogen-bonded to the amide oxygen is -18.0 ppm, These LORG results support the conclusion that no more than four water molecules are hydrogen-bonded to the amide oxygen in formamide. (C) 1997 Academic Press. | en |
| heal.publisher | Elsevier | en |
| heal.journalName | Journal of Magnetic Resonance | en |
| heal.journalType | peer reviewed | - |
| heal.fullTextAvailability | TRUE | - |
| Appears in Collections: | Άρθρα σε επιστημονικά περιοδικά ( Ανοικτά). ΧΗΜ | |
Files in This Item:
| File | Description | Size | Format | |
|---|---|---|---|---|
| Diez-1997-Solvent effects on o.pdf | 199.11 kB | Adobe PDF | View/Open Request a copy |
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