scholarly journals Interactions of Aggregating Peptides Probed by IR-UV Action Spectroscopy

2018 ◽  
Author(s):  
Sjors Bakels ◽  
E.M. Meijer ◽  
Mart Greuell ◽  
Sebastiaan Porskamp ◽  
George Rouwhorst ◽  
...  
Keyword(s):  
Hydrogen Bond ◽  
Hydrogen Bonds ◽  
Self Assembly ◽  
Intermolecular Hydrogen Bond ◽  
Beta Sheet ◽  
Dispersion Interactions ◽  
Intramolecular Hydrogen Bonds ◽  
Action Spectroscopy ◽  
Hydrogen Bond Interactions ◽  
Intramolecular Hydrogen

Peptide aggregation, the self-assembly of peptides into structured beta-sheet fibril structures, is driven by a combination of intra- and intermolecular interactions. Here, the interplay between intramolecular and formed inter-sheet hydrogen bonds and the effect of dispersion interactions on the formation of neutral, isolated, peptide dimers is studied by infrared action spectroscopy. Therefore, four different homo- and hetereogeneous dimers formed from three different alanine-based model peptides have been studied under controlled and isolated conditions. The peptides differ from one another in the presence and location of a UV chromophore containing cap on either the C- or N-terminus. Conformations of the monomers of the peptides direct the final dimer structure: strongly hydrogen bonded or folded structures result in weakly bound dimers. Here the intramolecular hydrogen bonds are favored over new intermolecular hydrogen bond interactions. In contrast, linearly folded monomers are the ideal template to form parallel beta-sheet type structures. The weak intramolecular hydrogen bonds present in the linear monomers are replaced by the stronger inter-sheet hydrogen bond interactions. The influence of π-π disperion interactions on the structure of the dimer is minimal, the phenyl rings have the tendency to fold away from the peptide backbone to favour intermolecular hydrogen bond interactions. Quantum chemical calculations confirm our experimental observations.

Interactions of Aggregating Peptides Probed by IR-UV Action Spectroscopy

2018 ◽  
Author(s):  
Sjors Bakels ◽  
E.M. Meijer ◽  
Mart Greuell ◽  
Sebastiaan Porskamp ◽  
George Rouwhorst ◽  
...  
Keyword(s):  
Hydrogen Bond ◽  
Hydrogen Bonds ◽  
Self Assembly ◽  
Intermolecular Hydrogen Bond ◽  
Beta Sheet ◽  
Dispersion Interactions ◽  
Intramolecular Hydrogen Bonds ◽  
Action Spectroscopy ◽  
Hydrogen Bond Interactions ◽  
Intramolecular Hydrogen

Peptide aggregation, the self-assembly of peptides into structured beta-sheet fibril structures, is driven by a combination of intra- and intermolecular interactions. Here, the interplay between intramolecular and formed inter-sheet hydrogen bonds and the effect of dispersion interactions on the formation of neutral, isolated, peptide dimers is studied by infrared action spectroscopy. Therefore, four different homo- and hetereogeneous dimers formed from three different alanine-based model peptides have been studied under controlled and isolated conditions. The peptides differ from one another in the presence and location of a UV chromophore containing cap on either the C- or N-terminus. Conformations of the monomers of the peptides direct the final dimer structure: strongly hydrogen bonded or folded structures result in weakly bound dimers. Here the intramolecular hydrogen bonds are favored over new intermolecular hydrogen bond interactions. In contrast, linearly folded monomers are the ideal template to form parallel beta-sheet type structures. The weak intramolecular hydrogen bonds present in the linear monomers are replaced by the stronger inter-sheet hydrogen bond interactions. The influence of π-π disperion interactions on the structure of the dimer is minimal, the phenyl rings have the tendency to fold away from the peptide backbone to favour intermolecular hydrogen bond interactions. Quantum chemical calculations confirm our experimental observations.

Solvent effects on the infrared spectra of anilines. VII. 2-Substituted 4-nitroanilines

1970 ◽  
Vol 23 (5) ◽  
pp. 947 ◽  
Author(s):  
LK Dyall
Keyword(s):  
Hydrogen Bond ◽  
Hydrogen Bonds ◽  
Infrared Spectra ◽  
Solvent Effects ◽  
Intermolecular Hydrogen Bond ◽  
Lone Pair ◽  
Acceptor Molecule ◽  
Intramolecular Hydrogen Bonds ◽  
Intramolecular Hydrogen ◽  
Ortho Substituent

Measurements of N-H stretching frequencies of 4-nitroanilines in the presence of hydrogen bond acceptors show that the ease of forming a second intermolecular hydrogen bond in the presence of an ortho substituent decreases in the order hydrogen > methyl > bromo, methoxyl > nitro. This order demonstrates the importance of repulsions between lone pair orbitals on the ortho substituent and the acceptor molecule. Weak intramolecular hydrogen bonds are detected in 2-iodo- and 2-bromo-aniline, and such bonds can be strengthened by introduction of a 4-nitro substituent.

CB-TE2A+·Cl−·3H2O: a short intermolecular hydrogen bond between zwitterionic bicyclo[6.6.2]tetraamine macrocycles

2016 ◽  
Vol 72 (2) ◽  
pp. 139-142 ◽  
Author(s):  
Paul Jurek ◽  
Joseph H. Reibenspies ◽  
Garry E. Kiefer
Keyword(s):  
Hydrogen Bond ◽  
Hydrogen Bonds ◽  
Carbonyl Group ◽  
Copper Complexes ◽  
Intermolecular Hydrogen Bond ◽  
Zigzag Chain ◽  
Intramolecular Hydrogen Bonds ◽  
Amine Groups ◽  
Intramolecular Hydrogen

1,4,8,11-Tetraazabicyclo[6.6.2]hexadecane-4,11-diacetic acid (CB-TE2A) is of much interest in nuclear medicine for its ability to form copper complexes that are kinetically inert, which is beneficialin vivoto minimize the loss of radioactive copper. The structural chemistry of the hydrated HCl salt of CB-TE2A, namely 11-carboxymethyl-1,8-tetraaza-4,11-diazoniabicyclo[6.6.2]hexadecane-4-acetate chloride trihydrate, C16H31N4O4+·Cl−·3H2O, is described. The compound crystallized as a positively charged zwitterion with a chloride counter-ion. Two of the amine groups in the macrocyclic ring are protonated. Formally, a single negative charge is shared between two of the carboxylic acid groups, while one chloride ion balances the charge. Two intramolecular hydrogen bonds are observed between adjacent pairs of N atoms of the macrocycle. Two intramolecular hydrogen bonds are also observed between the protonated amine groups and the pendant carboxylate groups. A short intermolecular hydrogen bond is observed between two partially negatively charged O atoms on adjacent macrocycles. The result is a one-dimensional polymeric zigzag chain that propagates parallel to the crystallographicadirection. A second intermolecular interaction is a hydrogen-bonding network in the crystallographicbdirection. The carbonyl group of one macrocycle is connected through the three water molecules of hydration to the carbonyl group of another macrocycle.

Halogen Bonding Organocatalysis Enhanced through Intramolecular Hydrogen Bonds

2022 ◽  
Author(s):  
Asia Marie S Riel ◽  
Daniel Adam Decato ◽  
Jiyu Sun ◽  
Orion Berryman
Keyword(s):  
Hydrogen Bond ◽  
Hydrogen Bonds ◽  
Halogen Bond ◽  
Direct Interaction ◽  
Halogen Bonding ◽  
Intramolecular Hydrogen Bonds ◽  
Intramolecular Hydrogen

Recent results indicate a halogen bond donor is strengthened through direct interaction with a hydrogen bond to the electron-rich belt of the halogen. Here, this Hydrogen Bond enhanced Halogen Bond...

Intramolecular hydrogen bonds and the orientation of amino groupsin o-phenylenediamines

1967 ◽  
Vol 45 (19) ◽  
pp. 2135-2141 ◽  
Author(s):  
P. J. Krueger
Keyword(s):  
Hydrogen Bond ◽  
Hydrogen Bonds ◽  
Infrared Absorption ◽  
Substituent Effect ◽  
Proton Donor ◽  
Proton Acceptor ◽  
Amino Groups ◽  
Intramolecular Hydrogen Bonds ◽  
Infrared Absorption Spectra ◽  
Intramolecular Hydrogen

The infrared absorption spectra of partially deuterated o-phenylenediamine and 4,5-di-methyl-, 4-methyl-, and 4-chloro-o-phenylenediamine in dilute CCl4 solution show double intramolecular [Formula: see text] hydrogen bonds in which the two NHD groups are equivalent and each group acts as both a proton donor and a proton acceptor. The ring substituent effect on this interaction in these compounds is small. In 4-methoxy-o-phenylenediamine, the amino groups are not equivalent, but double intramolecular hydrogen bonds are still present. In 4-nitro-o-phenylenediamine, only one intramolecular [Formula: see text] hydrogen bond appears to exist. The effect of N-substitution on some of these observations is discussed.

scholarly journals Synthesis and Heterocyclization of 4-Hydroxy-3 - ((2-hydroxy-4,4-dimethyl-6-oxocyclohex1-en-1-yl) (aryl) methyl) -2H-chromen-2-ones

2020 ◽  
Vol 20 (4) ◽  
pp. 362-371
Author(s):  
Alexander Yu. Kostritskiy ◽  
◽  
Marina G. Nakonechnikova ◽  
Olga V. Fedotova ◽  
Nina V. Pchelintseva ◽  
...  
Keyword(s):  
Hydrogen Bond ◽  
Hydrogen Bonds ◽  
13C Nmr ◽  
Intermediate Complex ◽  
Intramolecular Hydrogen Bonds ◽  
Propionic Anhydride ◽  
Intramolecular Hydrogen ◽  
Aryl Methyl

The possibility of obtaining asymmetric 1,5-diketones based on 4-hydroxy-2H-chromen-2-one and dimedone by three-component condensation in the presence of L-proline as a catalyst is shown. As a result, a series of 4-hydroxy3 - ((2-hydroxy-4,4-dimethyl-6-oxocyclohex1-en-1-yl) (aryl) methyl) -2H-chromen-2-ones was obtained with a yield of 25 up to 73%. The study revealed that the highest yield was observed for compounds containing fragments of ortho-substituted aldehydes capable of forming a hydrogen bond. For meta- and para-substituted – the lowest yield was observed. In the case of ortho-substitution this can be probably explained due to the stabilization of the intermediate complex by two intramolecular hydrogen bonds, which makes it possible to selectively obtain only one final product – 4-hydroxy-3 -((2-hydroxy4,4-dimethyl-6-oxocyclohex-1- en-1-yl) (aryl) methyl) -2Hchromen-2-one. The structure of the obtained products was confirmed by 1 H, 13C NMR, HSQC, HMBC spectroscopy. Considering the 1,5-diketone fragment for the above-described compounds, the possibility of their O-heterocyclization by propionic anhydride was suggested. Boiling 4-hydroxy-3 - ((2-hydroxy-4,4-dimethyl-6-oxocyclohex-1-en-1-yl) (aryl) methyl) -2Hchromen-2-ones in anhydride medium for an hour resulted in obtaining a series of 7- (aryl) -10,10-dimethyl-7,9,10,11-tetrahydro-6H, 8H-chromeno [4,3-b] chromene-6,8-diones. Their structure was also confirmed by 1 H, 13C NMR, HSQC, HMBC spectroscopy.

scholarly journals New Insights Into the Structure of Hydroxylated and Alkylated Glycols: A Comparative X-ray Diffraction, Raman and Molecular Dynamics Study of Ethane-1,2-Diol, 2-Methoxyethan-1-ol and 1,2-Dimethoxy Ethane

2020 ◽  
Author(s):  
Lorenzo Gontrani ◽  
Pietro Tagliatesta ◽  
Antonio Agresti ◽  
Sara Pescetelli ◽  
Marilena Carbone
Keyword(s):  
Molecular Dynamics ◽  
Hydrogen Bond ◽  
Room Temperature ◽  
Intermolecular Hydrogen Bond ◽  
Hydroxyl Groups ◽  
Gauche Conformation ◽  
X Ray ◽  
Hydrogen Bond Interactions ◽  
Diffraction Patterns ◽  
Intramolecular Hydrogen

In this study, we report a detailed experimental and theoretical investigation of three glycols, namely ethane-1,2-diol, 2-methoxyethan-1-ol and 1,2-dimethoxy ethane. For the first time, the X-Ray spectra of the latter two liquids was measured at room temperature, and they were compared with the newly measured spectrum of ethane-1,2-diol. The experimental diffraction patterns were interpreted very satisfactorily with molecular dynamics calculations, and suggest that in liquid ethane-1,2-diol most molecules are found in gauche conformation, with intramolecular hydrogen bond between the two hydroxyl groups. Intramolecular H-bonds are established in the mono-alkylated diol, but the interaction is weaker. The EDXD study also evidences strong intermolecular hydrogen-bond interactions, with short O···O correlations in both systems, while longer methyl-methyl interactions are found in 1,2-dimethoxy ethane. X-Ray studies are complemented by micro Raman investigations at room temperature and at 80°C, that confirm the conformational analysis predicted by X-Ray experiments and simulations.

NUCLEAR SHIELDING PARAMETERS FOR PROTONS IN HYDROGEN BONDS: II. CORRELATION OF CHEMICAL SHIFTS IN INTRAMOLECULAR HYDROGEN BONDS WITH INFRARED STRETCHING FREQUENCIES

1960 ◽  
Vol 38 (8) ◽  
pp. 1249-1254 ◽  
Author(s):  
L. W. Reeves ◽  
E. A. Allan ◽  
K. O. Strømme
Keyword(s):  
Hydrogen Bond ◽  
Chemical Shift ◽  
Hydrogen Bonds ◽  
Infinite Dilution ◽  
Chemical Shifts ◽  
Intramolecular Hydrogen Bonds ◽  
A Value ◽  
Nuclear Shielding ◽  
Intramolecular Hydrogen ◽  
Hydrogen Bonded

Nuclear shielding parameters have been obtained for 24 intramolecularly hydrogen-bonded phenols and naphthols. The shielding parameters are corrected for large diamagnetic anisotropies and a value ΔσOH obtained which represents the change in shielding parameter in parts per million with reference to the infinite dilution chemical shift of phenol, α-naphthol, or β-naphthol. These values of ΔσOH are approximately proportional to the change ΔvOH in the OH stretching frequency on formation of the hydrogen bond.

Universal prediction of intramolecular hydrogen bonds in organic crystals

2010 ◽  
Vol 66 (2) ◽  
pp. 237-252 ◽  
Author(s):  
Peter T. A. Galek ◽  
László Fábián ◽  
Frank H. Allen
Keyword(s):  
Hydrogen Bond ◽  
Hydrogen Bonds ◽  
Probability Model ◽  
Organic Crystals ◽  
Intramolecular Hydrogen Bonds ◽  
Donor And Acceptor ◽  
Universal Prediction ◽  
Structural Database ◽  
Chemical Descriptors ◽  
Intramolecular Hydrogen

A complete exploration of intramolecular hydrogen bonds (IHBs) has been undertaken using a combination of statistical analyses of the Cambridge Structural Database and computation of ab initio interaction energies for prototypical hydrogen-bonded fragments. Notable correlations have been revealed between computed energies, hydrogen-bond geometries, donor and acceptor chemistry, and frequencies of occurrence. Significantly, we find that 95% of all observed IHBs correspond to the five-, six- or seven-membered rings. Our method to predict a propensity for hydrogen-bond occurrence in a crystal has been adapted for such IHBs, applying topological and chemical descriptors derived from our findings. In contrast to intermolecular hydrogen bonding, it is found that IHBs can be predicted across the complete chemical landscape from a single optimized probability model, which is presented. Predictivity of 85% has been obtained for generic organic structures, which can exceed 90% for discrete classes of IHB.

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