Journal of Molecular Modeling

, Volume 19, Issue 4, pp 1695–1704

DFT studies on the intrinsic conformational properties of non-ionic pyrrolysine in gas phase

Original Paper

DOI: 10.1007/s00894-012-1740-5

Cite this article as:
Das, G. & Mandal, S. J Mol Model (2013) 19: 1695. doi:10.1007/s00894-012-1740-5


B3LYP/6-31G(d,p) level of theory is used to carry out a detailed gas phase conformational analysis of non-ionized (neutral) pyrrolysine molecule about its nine internal back-bone torsional angles. A total of 13 minima are detected from potential energy surface exploration corresponding to the nine internal back-bone torsional angles. These minima are then subjected to full geometry optimization and vibrational frequency calculations at B3LYP/6-31++G(d,p) level. Characteristic intramolecular hydrogen bonds present in each conformer, their relative energies, theoretically predicted vibrational spectra, rotational constants and dipole moments are systematically reported. Single point calculations are carried out at B3LYP/6-311++G(d,p) and MP2/6-31++G(d,p) levels. Six types of intramolecular H-bonds, viz. O…H–O, N…H-O, O…H–N, N…H–N, O…H–C and N…H–C, are found to exist in the pyrrolysine conformers; all of which contribute to the stability of the conformers. The vibrational frequencies are found to shift invariably toward the lower side of frequency scale corresponding to the presence of intramolecular H-bond interactions in the conformers.


DFT conformational analysis Intrinsic conformational properties Pyrrolysine conformers Vibrational frequencies 

Supplementary material

894_2012_1740_MOESM1_ESM.doc (1.3 mb)
ESM 1(DOC 1330 kb)

Copyright information

© Springer-Verlag Berlin Heidelberg 2013

Authors and Affiliations

  1. 1.Department of ChemistryNorth Eastern Hill UniversityShillongIndia

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