Ab initio molecular orbital calculations of solvent clusters of trans-N-methylacetamide: Structure, ring cluster formation and out-of-plane deformation
Φόρτωση...
Ημερομηνία
Συγγραφείς
Demetropoulos, I. N.
Gerothanassis, I. P.
Vakka, C.
Kakavas, C.
Τίτλος Εφημερίδας
Περιοδικό ISSN
Τίτλος τόμου
Εκδότης
Royal Society of Chemistry
Περίληψη
Τύπος
Είδος δημοσίευσης σε συνέδριο
Είδος περιοδικού
peer reviewed
Είδος εκπαιδευτικού υλικού
Όνομα συνεδρίου
Όνομα περιοδικού
Journal of the Chemical Society-Faraday Transactions
Όνομα βιβλίου
Σειρά βιβλίου
Έκδοση βιβλίου
Συμπληρωματικός/δευτερεύων τίτλος
Περιγραφή
The solvation of trans amides has been investigated by the use of full gradient optimization ab initio quantum mechanical calculation techniques. The complexes have been determined at the Hartree-Fock (HF) level with a 4-31G*/4-31G** basis set and at the second-order Moller-Plesset perturbation (MP2) level. Three NMA-water clusters were investigated: trans-NMA with two molecules of water forming a ring cluster at the amide oxygen; trans-NMA with two molecules of water at the amide oxygen forming hydrogen bonds along the direction of the lone-pair electrons; trans-NMA with one molecule of water at the CO group and one at the NH group. In addition, 4-31G* basis set calculations for trans-NMA with two molecules of acetonitrile were performed. The C=O ... H(W) hydrogen bond lengths, electron-density population analysis and molecular-orbital analysis of trans-NMA with two molecules of water at the amide oxygen demonstrate the importance of concurrent water-water and water-(carbonyl) oxygen hydrogen-bond interactions. The complex of trans-NMA with two molecules of water forming a ring cluster at the amide oxygen indicates the formation of a non-planar amide bond and the generation of a chiral centre at the amide nitrogen; this structure has a 5% Boltzmann distribution at room temperature at the MP2 level. Vibrational-frequency analysis shows that its hydrogen-bonded water molecules are vibrationally coupled. Orbital analysis suggests that there is a considerable solute-occupied space reorganization caused by the rearrangement of the water solvent molecules. Comparisons are made with previous theoretical studies of amide-water interactions and experimental spectroscopic, X-ray and neutron-diffraction data on the hydration of amides, peptides and proteins.
Περιγραφή
Λέξεις-κλειδιά
aqueous-solution, excited-state, peptide-bond, amide group, abinitio, hydration, acetonitrile, biomolecules, water, spectroscopy
Θεματική κατηγορία
Παραπομπή
Σύνδεσμος
<Go to ISI>://A1996UD00200005
http://pubs.rsc.org/en/Content/ArticleLanding/1996/FT/ft9969200921
http://pubs.rsc.org/en/Content/ArticleLanding/1996/FT/ft9969200921
Γλώσσα
en
Εκδίδον τμήμα/τομέας
Όνομα επιβλέποντος
Εξεταστική επιτροπή
Γενική Περιγραφή / Σχόλια
Ίδρυμα και Σχολή/Τμήμα του υποβάλλοντος
Πανεπιστήμιο Ιωαννίνων. Σχολή Θετικών Επιστημών. Τμήμα Χημείας