The achiral tetrapeptideZ-Aib-Aib-Aib-Gly-OtBu

2014 ◽  
Vol 70 (11) ◽  
pp. 1046-1049 ◽  
Author(s):  
Renate Gessmann ◽  
Hans Brückner ◽  
Kyriacos Petratos
Keyword(s):  
Hydrogen Bonds ◽  
Butyl Ester ◽  
Relative Orientation ◽  
Asymmetric Unit ◽  
Intramolecular Hydrogen Bonds ◽  
Aminoisobutyric Acid ◽  
C Terminus ◽  
Intramolecular Hydrogen

The title achiral peptideN-benzyloxycarbonyl-α-aminoisobutyryl-α-aminoisobutyryl-α-aminoisobutyrylglycinetert-butyl ester orZ-Aib-Aib-Aib-Gly-OtBu (Aib is α-aminoisobutyric acid,Zis benzyloxycarbonyl, Gly is glycine and OtBu indicates thetert-butyl ester), C26H40N4O7, is partly hydrated (0.075H2O) and has two different conformations which together constitute the asymmetric unit. Both molecules form incipient 310-helices. They differ in the relative orientation of the N-terminal protection group and at the C-terminus. There are two 4→1 intramolecular hydrogen bonds.

scholarly journals The peptideZ-Aib-Aib-Aib-L-Ala-OtBu

2014 ◽  
Vol 70 (4) ◽  
pp. 405-407 ◽  
Author(s):  
Renate Gessmann ◽  
Hans Brückner ◽  
Kyriacos Petratos
Keyword(s):  
Hydrogen Bonds ◽  
Butyl Ester ◽  
Intramolecular Hydrogen Bonds ◽  
Aminoisobutyric Acid ◽  
Left Handed ◽  
Intramolecular Hydrogen ◽  
Hydrogen Bonded

The title peptide,N-benzyloxycarbonyl-α-aminoisobutyryl-α-aminoisobutyryl-α-aminoisobutyryl-L-alaninetert-butyl ester orZ-Aib-Aib-Aib-L-Ala-OtBu (Aib is α-aminoisobutyric acid,Zis benzyloxycarbonyl and OtBu indicates thetert-butyl ester), C27H42N4O7, is a left-handed helix with a right-handed conformation in the fourth residue, which is the only chiral residue. There are two 4→1 intramolecular hydrogen bonds in the structure. In the lattice, molecules are hydrogen bonded to form columns along thecaxis.

Two polymorphs ofN-(2-methoxyphenyl)-4-oxo-4H-chromone-3-carboxamide

2013 ◽  
Vol 69 (8) ◽  
pp. 927-933 ◽  
Author(s):  
Ligia R. Gomes ◽  
John Nicolson Low ◽  
Fernanda Borges ◽  
Fernando Cagide
Keyword(s):  
Hydrogen Bonds ◽  
Molecular Conformation ◽  
Three Dimensional ◽  
Amide Group ◽  
Monoclinic Space Group ◽  
Asymmetric Unit ◽  
Intramolecular Hydrogen Bonds ◽  
Compound C ◽  
Dimensional Network ◽  
Intramolecular Hydrogen

The title compound, C17H13NO4, crystallizes in two polymorphic forms, each with two molecules in the asymmetric unit and in the monoclinic space groupP21/c. All of the molecules have intramolecular hydrogen bonds involving the amide group. The amide N atoms act as donors to the carbonyl group of the pyrone and also to the methoxy group of the benzene ring. The carbonyl O atom of the amide group acts as an acceptor of the β and β′ C atoms belonging to the aromatic rings. These intramolecular hydrogen bonds have a profound effect on the molecular conformation. In one polymorph, the molecules in the asymmetric unit are linked to form dimers by weak C—H...O interactions. In the other, the molecules in the asymmetric unit are linked by a single weak C—H...O hydrogen bond. Two of these units are linked to form centrosymmetric tetramers by a second weak C—H...O interaction. Further interactions of this type link the molecules into chains, so forming a three-dimensional network. These interactions in both polymorphs are supplemented by π–π interactions between the chromone rings and between the chromone and methoxyphenyl rings.

scholarly journals Crystal structure of (μ-1,4-dicarboxybutane-1,4-dicarboxylato)bis[bis(triphenylphosphane)silver(I)] dichloromethane trisolvate

2016 ◽  
Vol 72 (2) ◽  
pp. 215-219 ◽  
Author(s):  
Peter Frenzel ◽  
Marcus Korb ◽  
Heinrich Lang
Keyword(s):  
Molecular Structure ◽  
Crystal Structure ◽  
Hydrogen Bonds ◽  
Carboxylate Group ◽  
Tetracarboxylic Acid ◽  
Asymmetric Unit ◽  
Coordination Environment ◽  
Intramolecular Hydrogen Bonds ◽  
Phenyl Rings ◽  
Intramolecular Hydrogen

The molecular structure of the tetrakis(triphenylphosphanyl)disilver salt of butane-1,1,4,4-tetracarboxylic acid, [Ag2(C8H8O8)(C18H15P)4]·3CH2Cl2, crystallizes with one and a half molecules of dichloromethane in the asymmetric unit. The coordination complex exhibits an inversion centre through the central CH2—CH2bond. The AgIatom has a distorted trigonal–planar P2O coordination environment. The packing is characterized by intermolecularT-shaped π–π interactions between the phenyl rings of the PPh3substituents in neighbouring molecules, forming a ladder-type superstructure parallel to [010]. These ladders are arranged in layers parallel to (101). Intramolecular hydrogen bonds between the OH group and one O atom of the Ag-bonded carboxylate group results in an asymmetric bidendate coordination of the carboxylate moiety to the AgIion.

Structure of Z-(Aib)9OBu t

1998 ◽  
Vol 54 (3) ◽  
pp. 300-307 ◽  
Author(s):  
R. Geßmann ◽  
H. Brückner ◽  
M. Kokkinidis
Keyword(s):  
Title Compound ◽  
The Other ◽  
Asymmetric Unit ◽  
X Ray ◽  
Aminoisobutyric Acid ◽  
X Ray Crystallography ◽  
C Terminus ◽  
Independent Molecules ◽  
Intramolecular Hydrogen ◽  
Layer Chromatography

The structure of the synthetic protected oligopeptide Z-(Aib)9OBu t , tert-butoxynona(α-aminoisobutyric acid), which contains the unusual α-aminoisobutyric acid (Aib), was determined by X-ray crystallography. The two independent molecules in the asymmetric unit fold into 310-helices, each stabilized by seven intramolecular hydrogen bonds. The C terminus of one of the molecules is disordered and adopts a semi-extended conformation, which is rather unusual for Aib residues. This is the first observation of such a conformation involved in a disorder in Aib-containing oligopeptides. The existence of a second conformation for the C-terminal residue might explain the difficulties in crystallizing the title compound and a different behaviour of the title compound in thin layer chromatography compared with the other homopeptides.

The first N-terminal unprotected (Gly-Aib)npeptide: H-Gly-Aib-Gly-Aib-OtBu

2015 ◽  
Vol 71 (12) ◽  
pp. 1114-1117 ◽  
Author(s):  
Renate Gessmann ◽  
Hans Brückner ◽  
Kyriacos Petratos
Keyword(s):  
Hydrogen Bond ◽  
Butyl Ester ◽  
Conformational Space ◽  
Aminoisobutyric Acid ◽  
Left Handed ◽  
C Terminus ◽  
Backbone Conformation ◽  
Intramolecular Hydrogen ◽  
The Right ◽  
Helical Region

Glycine (Gly) is incorporated in roughly half of all known peptaibiotic (nonribosomally biosynthesized antibiotic peptides of fungal origin) sequences and is the residue with the greatest conformational flexibility. The conformational space of Aib (α-aminoisobutyric acid) is severely restricted by the second methyl group attached to the Cαatom. Most of the crystal structures containing Aib are N-terminal protected. Deprotection of the N- or C-terminus of peptides may alter the hydrogen-bonding scheme and/or the structure and may facilitate crystallization. The structure reported here for glycyl-α-aminoisobutyrylglycyl-α-aminoisobutyric acidtert-butyl ester, C16H30N4O5, describes the first N-terminal-unprotected (Gly-Aib)npeptide. The achiral peptide could form an intramolecular hydrogen bond between the C=O group of Gly1 and the N—H group of Aib4. This hydrogen bond is found in all tetrapeptides and N-terminal-protected tripeptides containing Aib, apart from one exception. In the present work, this hydrogen bond is not observed (N...O = 5.88 Å). Instead, every molecule is hydrogen bonded to six other symmetry-related molecules with a total of eight hydrogen bonds per molecule. The backbone conformation starts in the right-handed helical region (and the left-handed helical region for the inverted molecule) and reverses the screw sense in the last two residues.

Controlling emissive properties by intramolecular hydrogen bonds: alkyl and aryl meso‐substituted porphycenes

2021 ◽  
Author(s):  
Jacek Waluk ◽  
Arkadiusz Listkowski ◽  
Natalia Masiera ◽  
Michał Kijak ◽  
Roman Luboradzki ◽  
...  
Keyword(s):  
Hydrogen Bonds ◽  
Intramolecular Hydrogen Bonds ◽  
Intramolecular Hydrogen

Energies of intramolecular hydrogen bonds in some alcohols

1974 ◽  
Vol 20 (3) ◽  
pp. 414-415
Author(s):  
Ya. A. Shuster ◽  
V. A. Granzhan ◽  
P. M. Zaitsev
Keyword(s):  
Hydrogen Bonds ◽  
Intramolecular Hydrogen Bonds ◽  
Intramolecular Hydrogen

Hydrogen bonds in derivatives of N-substituted N’-benzoyl- and N’-(2-chlorobenzoyl)thiourea

1991 ◽  
Vol 56 (4) ◽  
pp. 880-885 ◽  
Author(s):  
Oľga Hritzová ◽  
Dušan Koščík
Keyword(s):  
Hydrogen Bonds ◽  
Spectral Studies ◽  
Intramolecular Hydrogen Bonds ◽  
Tautomeric Forms ◽  
Intramolecular Hydrogen ◽  
Derivatives Of

Intramolecular hydrogen bonds of the N-H···O=C type have been detected in the derivatives of N-substituted N’-benzoyl- and N’-(2-chlorobenzoyl)thiourea on the basis of IR spectral studies. The title compounds can exist in two tautomeric forms.

Spin-spin coupling via intramolecular hydrogen bonds

1985 ◽  
Vol 25 (5) ◽  
pp. 808-810
Author(s):  
L. N. Kurkovskaya ◽  
Yu. M. Chunaev ◽  
N. M. Przhiyalgovskaya
Keyword(s):  
Hydrogen Bonds ◽  
Spin Coupling ◽  
Intramolecular Hydrogen Bonds ◽  
Intramolecular Hydrogen ◽  
Spin Spin Coupling
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