Chirality Effects in Jet-Cooled Cyclic Dipeptides

Pérez‐Mellor, Ariel; Zehnacker, Anne

doi:10.1007/978-981-13-9371-6_3

Cited by 7 publications

(14 citation statements)

References 79 publications

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“…The lack of optical activity can be due to two reasons. First, c‐LD could be a C i molecule, devoid of chirality due to the presence of a center of symmetry . In this case, c‐LD and c‐DL are identical non‐chiral molecules.…”

Section: Resultsmentioning

confidence: 99%

“…We have recently compared the structure of jet‐cooled diphenylalanine, denoted as LL hereafter, and cyclo diphenylalanine, denoted as c‐LL, to that of their diastereomer LD diphenylalanine (LD) and cyclo LD diphenylalanine (c‐LD). Conformer‐selective vibrational spectroscopy compared with quantum chemical calculations indicates that the structural differences between the two diastereomers are small . c‐LL and c‐LD both show a folded‐extended conformation, with one of the aromatic ring folded over the dipeptide frame and the other one extended outwards.…”

Section: Introductionmentioning

confidence: 97%

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Solid‐state synthesis of cyclo LD‐diphenylalanine: A chiral phase built from achiral subunits

2020

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The solid-state structure of LL/DD or LD/DL diphenylalanine diluted in KBr pellets is studied by infrared (IR) absorption and vibrational circular dichroism (VCD) spectroscopy. The structure depends on the absolute configuration of the residues. The natural LL diphenylalanine exists as a mixture of neutral and zwitterionic structures, depending on the humidity of the sample, while mostly the zwitterion is observed for LD diphenylalanine whatever the experimental conditions. The system undergoes spontaneous cyclization upon heating at 125 C, resulting to the formation of a diketopiperazine (DKP) dipeptide as the only product. The reaction is faster for LD than for LL diphenylalanine. As expected, LL and DD diphenylalanine react to form the LL and DD enantiomers of cyclo diphenylalanine. Interestingly, the DKP dipeptides formed from the LD or DL diphenylalanine show unexpected optical activity, with opposite VCD spectra for the products formed from the LD and DL reagents. This is explained in terms of chirality synchronization between the monomers within the crystal, which retain the symmetry of the reagent, resulting to the formation of a new chiral phase made from transiently chiral molecules. K E Y W O R D Schirality synchronization, diketopiperazine (DKP), peptides, vibrational circular dichroism (VCD), vibrational spectroscopy

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 97%

Solid‐state synthesis of cyclo LD‐diphenylalanine: A chiral phase built from achiral subunits

2020

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“…In a g + structure, the aromatic substituent is folded over the DKP ring while it is extended outwards in g − . 38,55 The trans geometry also corresponds to an extended aromatic ring, but with its plane almost perpendicular to the DKP ring. In addition, the two nitrogen atoms of the imidazole ring are named according to the IUPAC Compendium of Chemical Terminology, as proposed for HisH + .…”

Section: Experimental and Theoretical Methodsmentioning

confidence: 99%

“…The absolute configuration of the residues indeed influences the structure of cyclic dipeptides. 36–41 Cyclic dipeptides differ from linear ones in several aspects. First, the steric bias due to the ring imposes the non-usual cis conformation of the peptide bonds.…”

Section: Introductionmentioning

confidence: 99%

“…42 Cyclic dipeptides offer therefore a good model for studying the influence of the cis conformation of the peptide bond on aggregation. The cis conformation favours indeed the formation of two strong NH⋯O hydrogen bonds in the gas-phase dimer of cyclo (Phe-Phe) 43 or its crystal, 38,44 akin to an antiparallel β sheet. Second, the molecule is deprived of the amine and carboxylic functions present in peptides, preventing protonation on the N-terminus.…”

Section: Introductionmentioning

confidence: 99%

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How change in chirality prevents β-amyloid type interaction in a protonated cyclic dipeptide dimer

Barbu‐Debus

Pérez‐Mellor

Lepère

et al. 2022

Phys. Chem. Chem. Phys.

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Does Chiral Sensitivity of a Structure Depend on the Metal Core? Alkali Ion Complexes of Cyclo(Tyr‐Tyr)

et al. 2023

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Alkali metal complexes of cyclic dipeptide cyclo Tyr‐Tyr have been studied under cryogenic ion trap conditions. Their structure was obtained by combining Infra‐Red Photo‐Dissociation (IRPD) and quantum chemical calculations. The structural motif strongly depends on the relative chirality of the tyrosine residues. For residues of identical chirality, the cation interacts with one amide oxygen and one of the aromatic rings only; the distance between the aromatic rings does not change with the nature of the metal. In contrast, for residues of opposite chirality, the metal cation is located in between the two aromatic rings and interacts with both of them. The distance between the two aromatic rings strongly depends on the metal. Electronic spectra obtained by Ultra Violet Photodissociation (UVPD) spectroscopy and analysis of the UV photo‐fragments shed light on the excited state deactivation processes, which depend on both the chirality of the residue and that of the metal ion core. Na+ stands out by the presence of low‐lying charge transfer states resulting in the broadening of the electronic spectrum.

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Chirality Effects in Jet-Cooled Cyclic Dipeptides

Cited by 7 publications

References 79 publications

Solid‐state synthesis of cyclo LD‐diphenylalanine: A chiral phase built from achiral subunits

Solid‐state synthesis of cyclo LD‐diphenylalanine: A chiral phase built from achiral subunits

How change in chirality prevents β-amyloid type interaction in a protonated cyclic dipeptide dimer

Does Chiral Sensitivity of a Structure Depend on the Metal Core? Alkali Ion Complexes of Cyclo(Tyr‐Tyr)

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