The normal coordinate analysis of glycine anhydride (2,5-piperazinedione)

Asai, Masatomo; Noda, Kumo; Sadô, Akira

doi:10.1016/0584-8539(74)80030-9

Cited by 10 publications

(7 citation statements)

References 17 publications

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“…Tables 14 list the observed frequencies and their assignments. By comparison with spectra of less completely deuterated samples, we eliminated many bands as being due to impurities. We agree with ASAI et al [6] that the i.r. bands found near 1280 and 1290 cm-' in NdDKP are CHD absorptions.…”

Section: Ijlj!j'd K Lesupporting

confidence: 94%

“…Despite the large amount of work on DKP, some important aspects of the analysis are not yet satisfactory. In the i.r., the assignments of two peptide group vibrations, NH in-plane bend (ib) and CN stretch (str), and the CH2 bend mode are not unequivocal because only two bands have been observed in the 140&1500cm-' region; various schemes of overlap have had to be assumed [4,6,8]. The CO out-of-plane bend (ob) has either been left unassigned [IS,9] or was thought to be overlapped with CO ib [6].…”

Section: Diketopiperazinementioning

confidence: 99%

“…In the i.r., the assignments of two peptide group vibrations, NH in-plane bend (ib) and CN stretch (str), and the CH2 bend mode are not unequivocal because only two bands have been observed in the 140&1500cm-' region; various schemes of overlap have had to be assumed [4,6,8]. The CO out-of-plane bend (ob) has either been left unassigned [IS,9] or was thought to be overlapped with CO ib [6]. Each normal mode calculation has used an approximate structural model instead of the exact X-ray structure of DEGEILH and MARSH [ 111;moreover,FUKUSHIMA et al [9] and STEIN [8] took the CH2 groups to be point masses.…”

Section: Diketopiperazinementioning

confidence: 99%

“…All previous workers considered an isolated molecule in their calculations, except for STEIN who took into account in parts of his analysis the hydrogen bonds between translationally equivalent molecules in a chain. The force fields used were of the Urey-Bradley type, and only ASAI et al [6] attempted a systematic refinement of the force constants; these authors, however, did not use any Raman data, and there are significant discrepancies between calculated and observed frequencies for several i.r. modes.…”

Section: Diketopiperazinementioning

confidence: 99%

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Vibrational analysis of crystalline diketopiperazine—I. Raman and i.r. spectra

Cheam

Krimm

1984

Spectrochimica Acta Part A: Molecular Spectroscopy

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Raman and i.r. spectra have been obtained of diketopiperazine and five of its isotopic derivatives: (CONDCH,),, (CONHCDZ)2, (CONDCD2)2, ('3CONHCH2)2 and ('3CONDCH,)2. In addition to solution spectra and powder spectra at room and liquid nitrogen temperatures, polarized Raman spectra were obtained on single crystals. These data have permitted an essentially complete assignment to be made of the Raman and i.r. modes of the crystal, a necessary step in the refinement of an intramolecular force field for this molecule [ 131.

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Section: Ijlj!j'd K Lesupporting

confidence: 94%

Section: Diketopiperazinementioning

confidence: 99%

Section: Diketopiperazinementioning

confidence: 99%

Section: Diketopiperazinementioning

confidence: 99%

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Vibrational analysis of crystalline diketopiperazine—I. Raman and i.r. spectra

Cheam

Krimm

1984

Spectrochimica Acta Part A: Molecular Spectroscopy

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“…1) are all examples of molecules in which the amide group displays cis-geometry. [11,12] X-ray crystallographic data reported for cyclo(Gly-Gly), [13] which is also known as diketopiperazine (DKP), indicates that the ring is 'essentially planar,' and that cyclo(Gly-Gly) molecules are interconnected by hydrogen-bonded chains. Cyclo(D-Ala-L-Ala), [14,15] on the other hand, has been found to exist in two polymorphic forms.…”

Section: Introductionmentioning

confidence: 99%

Vibrational spectroscopy and DFT calculations of di‐amino acid cyclic peptides. Part I: cyclo(Gly‐Gly), cyclo(L‐Ala‐L‐Ala) and cyclo(L‐Ala‐Gly) in the solid state and in aqueous solution

Mendham

Dines

Snowden

et al. 2009

J Raman Spectroscopy

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Investigations of the vibrational spectra of cyclo(Gly-Gly), cyclo(L-Ala-L-Ala) and cyclo(L-Ala-Gly) are reported. Raman scattering and Fourier transform infrared (FTIR) spectra of solid-state and aqueous protonated samples, as well as their corresponding N-deuterated isotopomers, have been examined. In addition, density functional theory (DFT) (B3-LYP/cc-pVDZ) calculations of molecular structures and their associated vibrational modes were carried out. In each case, the calculated structures of lowest energy for the isolated gas-phase molecules have boat conformations. Assignments have been made for the observed Raman and FTIR vibrational bands of the cyclic di-amino acid peptides (CDAPs) examined. Raman polarization studies of aqueous phase samples are consistent with C 2 and C 1 symmetries for the six-membered rings of cyclo(L-Ala-L-Ala) and cyclo(L-Ala-Gly), respectively. There is a good correlation between experimental and calculated vibrational bands for the three CDAPs. These data are in keeping with boat conformations for cyclo(L-Ala-L-Ala) and cyclo(L-Ala-Gly) molecules, predicted by the ab initio calculations, in both the solid and aqueous solution states. However, Raman spectroscopic results might infer that cyclo(L-AlaGly) deviates only slightly from planarity in the solid state. The potential energy distributions of the amide I and II modes of a cis-peptide linkage are shown to be significantly different from those of the trans-peptides. For example, deuterium shifts have shown that the cis-amide I vibrations found in cyclo(Gly-Gly), cyclo(L-Ala-L-Ala), and cyclo(L-Ala-Gly) have larger N-H contributions compared to their trans-amide counterparts. Compared to trans-amide II vibrations, cis-amide II vibrations show a considerable decrease in N-H character.

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Dioxo‐2,5 pipérazines. 1. La synthèse des carboxythiazolo dioxo‐2,5 pipérazines

Jerumanis

Lemieux

1980

Journal of Heterocyclic Chem

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Line route nouvelle et générale pour préparer les carboxythiazolo dioxo‐2,5 pipérazines est decrite. Dansles reactions de formation du cycle de la dioxo‐2,5 pipérazine, la Néthoxycarbonyle éthoxy‐2 dihydro‐1,2 quinoléine (EEDQ) a été utilisée comme agent d'activation. Par cette méthode le butoxycarbonyl‐9 diméthyl‐7,7 dioxo‐2,5 thia‐8 diaza‐1,4 bicyclo[4,3,0]nonane (6) et le car‐boxy‐9 dimèthyl‐8,8 dioxo‐2,5 thia‐7 diaza‐1,4 bicyclo[4,3,0]nonane (8)ont été obtenus, avec un rendement quasi quantitatif, en utilisant la carboxy‐4 butoxycarbonyl‐2 diméthyl‐5,5 thiazolidine (4) comme produit de départ. L'ester 6 a été hydrolysé avec de l'hydroxyde de barium en acide correspondant 7 et l'acide 8 traité avec du diazométhane a donné l'ester 9. L'ester 6 a été synthé‐tisé aussi à partir de l'ester éthylique de la N‐(butoxycarbonyl‐2 carboxy‐4 diméthyl‐5,5 thiazoli‐dine)glycine (10). Les données spectroscopiques sont interprétées pour confirmer les structures de nouveaux produits obtenus.

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The normal coordinate analysis of glycine anhydride (2,5-piperazinedione)

Cited by 10 publications

References 17 publications

Vibrational analysis of crystalline diketopiperazine—I. Raman and i.r. spectra

Vibrational analysis of crystalline diketopiperazine—I. Raman and i.r. spectra

Vibrational spectroscopy and DFT calculations of di‐amino acid cyclic peptides. Part I: cyclo(Gly‐Gly), cyclo(L‐Ala‐L‐Ala) and cyclo(L‐Ala‐Gly) in the solid state and in aqueous solution

Dioxo‐2,5 pipérazines. 1. La synthèse des carboxythiazolo dioxo‐2,5 pipérazines

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