Hydrogen Bonding, the Driving Force for Increased Host Selectivities in Two-Solvent Mixed Complexes of TETROL Comprising Both Favored (Aniline) and Disfavored Guests (o-Toluidine or Toluene)

2018 ◽  
Vol 18 (6) ◽  
pp. 3569-3575 ◽  
Author(s):  
Benita Barton ◽  
Sasha-Lee Dorfling ◽  
Eric C. Hosten
Keyword(s):  
Hydrogen Bonding ◽  
Driving Force ◽  
Mixed Complexes

scholarly journals Intramolecular hydrogen bonding and conformational preferences on 2-fluoro-phenylaminocyclohexanol

2018 ◽  
Author(s):  
Cassia Chiari ◽  
Claudio Francisco Tormena ◽  
Kahlil Schwanka Salome ◽  
Laiza Bruzadelle Loureiro ◽  
Renan Vidal Viesser
Keyword(s):  
Hydrogen Bonding ◽  
Driving Force ◽  
Conformational Stability ◽  
Intramolecular Hydrogen Bonding ◽  
Quantum Mechanical ◽  
Resonance Spectroscopy ◽  
Quantum Mechanical Calculations ◽  
Conformational Preferences ◽  
Intramolecular Hydrogen ◽  
Theoretical Results

The aim of this study is to evaluate the influence and strength of possible intramolecular hydrogen bonding (IntraHB) involving N-H--O, O-H--N, O-H--F and N-H--F molecular moieties as a driving force on the conformational preferences of 2-fluoro-phenylaminocyclohexanol. To achieve our purpose we synthesized the compound and performed it's characterization using Nuclear Magnetic Resonance Spectroscopy (NMR). Quantum mechanical calculations were carried out to evaluate the effect of IntraHB on the conformational stability. Experimental and theoretical results showed that N-H--F and O-H--N IntraHB have a greater influence on the conformacional preferably adopted by the molecule.

Photoelectron spectroscopy of hydrogen-bonded systems: spectra of monomers, dimers and mixed complexes of carboxylic acids

1972 ◽  
Vol 331 (1585) ◽  
pp. 249-261 ◽  
Keyword(s):  
Hydrogen Bonding ◽  
Ionization Potential ◽  
Carboxylic Acids ◽  
Photoelectron Spectroscopy ◽  
Free Acid ◽  
Photoelectron Spectra ◽  
Target Chamber ◽  
Donor Group ◽  
Mixed Complexes ◽  
First Ionization Potential

By cooling the target chamber of a photoelectron spectrometer, the photoelectron spectra of dimers and mixed complexes of carboxylic acids have been obtained. By comparison of the spectra with each other and with those of the monomers, it has been possible to assign several bands to ionization from specific molecular orbitals. Hydrogen-bonding changes most ionization potentials of the monomers but not by more than about 0.5 eV. In particular, the ionization potential of an electron from a non-bonding orbital on the proton donor group is decreased and that from a non-bonding orbital on the electron donor group is increased. This is consistent with most theories of hydrogen bonding. In the mixed complexes it makes the first ionization potential higher than that of the free acids, dimers, however, are complicated by the initial degeneracy of their orbitals and this results in their first ionization potential being lower than for the free acid. There is also some evidence that the hydrogen bonds in a complex between different acids are of unequal strength.

scholarly journals Biantennary oligoglycines and glyco-oligoglycines self-associating in aqueous medium

2014 ◽  
Vol 10 ◽  
pp. 1372-1382 ◽  
Author(s):  
Svetlana V Tsygankova ◽  
Alexander A Chinarev ◽  
Alexander B Tuzikov ◽  
Nikolai Severin ◽  
Alexey A Kalachev ◽  
...  
Keyword(s):  
Hydrogen Bonding ◽  
Sialic Acid ◽  
Antiviral Activity ◽  
Aqueous Medium ◽  
General Formula ◽  
Driving Force ◽  
Polypeptide Chain ◽  
Chain Conformation ◽  
Mica Surface ◽  
Antenna Length

Oligoglycines designed in a star-like fashion, so-called tri- and tetraantennary molecules, were found to form highly ordered supramers in aqueous medium. The formation of these supramers occurred either spontaneously or due to the assistance of a mica surface. The driving force of the supramer formation is hydrogen bonding, the polypeptide chain conformation is related to the folding of helical polyglycine II (PG II). Tri- and tetraantennary molecules are capable of association if the antenna length reach 7 glycine (Gly) residues. Properties of similar biantennary molecules have not been investigated yet, and we compared their self-aggregating potency with similar tri- and tetraantennary analogs. Here, we synthesized oligoglycines of the general formula R-Gly n -Х-Gly n -R (X = -HN-(СН2) m -NH-, m = 2, 4, 10; n = 1–7) without pendant ligands (R = H) and with two pendant sialoligands (R = sialic acid or sialooligosaccharide). Biantennary oligoglycines formed PG II aggregates, their properties, however, differ from those of the corresponding tri- and tetraantennary oligoglycines. In particular, the tendency to aggregate starts from Gly4 motifs instead of Gly7. The antiviral activity of end-glycosylated peptides was studied, and all capable of assembling glycopeptides demonstrated an antiviral potency which was up to 50 times higher than the activity of peptide-free glycans.

scholarly journals Synthesis, Adsorption, and Recognition Properties of a Solid Symmetric Tetramethylcucurbit[6]uril-Based Porous Supramolecular Framework

2020 ◽  
Vol 2020 ◽  
pp. 1-10
Author(s):  
Fei-Yang Tian ◽  
Rui-Xue Cheng ◽  
Yun-Qian Zhang ◽  
Zhu Tao ◽  
Qian-Jiang Zhu
Keyword(s):  
Hydrogen Bonding ◽  
Volatile Organic Compounds ◽  
Organic Compounds ◽  
Outer Surface ◽  
Driving Force ◽  
Fluorescence Enhancement ◽  
Colour Change ◽  
Water Molecules ◽  
Supramolecular Framework ◽  
Volatile Organic

In this work, we reported a porous supramolecular framework (A) constructed of a symmetric tetramethylcucurbit[6]uril (TMeQ[6]) in aqueous HCl solutions; the driving force was the outer surface interaction of cucurbit[n]urils, as well as hydrogen bonding between latticed water molecules and portal carbonyl oxygens of TMeQ[6]. Adsorption experimental results revealed that the porous supramolecular framework can absorb certain fluorophore guests (FGs) to form luminescent assemblies (FG@As) by fluorescence enhancement or colour change, and some of them can respond to certain volatile organic compounds. Thus, the TMeQ[6]-based supramolecular framework could be used as a sensor for certain gas or volatile compounds.

Protein engineering to change thermal stability for food enzymes

1991 ◽  
Vol 19 (3) ◽  
pp. 655-662 ◽  
Author(s):  
Peter W. Goodenough ◽  
John A. Jenkins
Keyword(s):  
Thermal Stability ◽  
Hydrogen Bonding ◽  
Protein Engineering ◽  
Present State ◽  
Driving Force ◽  
Electrostatic Interactions ◽  
Food Industry ◽  
Large Contribution

Summary In this review we have briefly indicated how the present state of knowledge allows proteins to be mutated to increase or decrease stability. We have discussed experiments on both model proteins and those of relevance to the food industry, and show how hydrophobic forces are a major driving force for folding as well as having a major role in thermostability. We have also indicated the large contribution that hydrogen bonding, electrostatic interactions and, in a less well predicted way, disulphide bridges make to thermostability.

Understanding the mechanism of LCST phase separation of mixed ionic liquids in water by MD simulations

2016 ◽  
Vol 18 (33) ◽  
pp. 23238-23245 ◽  
Author(s):  
Yuling Zhao ◽  
Huiyong Wang ◽  
Yuanchao Pei ◽  
Zhiping Liu ◽  
Jianji Wang
Keyword(s):  
Ionic Liquid ◽  
Hydrogen Bonding ◽  
Ionic Liquids ◽  
Phase Separation ◽  
Amino Acid ◽  
Driving Force ◽  
Md Simulations ◽  
Liquid Mixtures ◽  
Hydrogen Bonding Interaction ◽  
Bonding Interaction

Hydrogen bonding interaction between amino acid anions is the driving force for the phase separation of aqueous ionic liquid mixtures.

Binary co-crystals of the active pharmaceutical ingredient 1,4-bis(4-pyridyl)-2,3-diaza-1,3-butadiene and camphoric acid

2014 ◽  
Vol 70 (1) ◽  
pp. 63-71 ◽  
Author(s):  
Kamal Kumar Bisht ◽  
Priyank Patel ◽  
Yadagiri Rachuri ◽  
Suresh Eringathodi
Keyword(s):  
Solid Solution ◽  
Hydrogen Bonding ◽  
Driving Force ◽  
Active Pharmaceutical Ingredient ◽  
X Ray Diffraction ◽  
Space Group ◽  
X Ray ◽  
Helical Twist ◽  
Crystallization Experiments ◽  
Camphoric Acid

Co-crystals comprising the active pharmaceutical ingredient 1,4-bis(4-pyridyl)-2,3-diaza-1,3-butadiene, C12H10N4, and the chiral co-formers (+)-, (−)- and (rac)-camphoric acid (cam), C10H16O4, have been synthesized. Two different stoichiometries of the API and co-former are obtained, namely 1:1 and 3:2. Crystallization experiments suggest that the 3:2 co-crystal is kinetically favoured over the 1:1 co-crystal. Single-crystal X-ray diffraction analysis of the co-crystals reveals N—H...O hydrogen bonding as the primary driving force for crystallization of the supramolecular structures. The 1:1 co-crystal contains undulating hydrogen-bonded ribbons, in which the chiral cam molecules impart a helical twist. The 3:2 co-crystal contains discrete Z-shaped motifs comprising three molecules of the API and two molecules of cam. The 3:2 co-crystals with (+)-cam, (−)-cam (space groupP21) and (rac)-cam (space groupP21/n) are isostructural. The enantiomeric co-crystals contain pseudo-symmetry consistent with space groupP21/n, and the co-crystal with (rac)-cam represents a solid solution between the co-crystals containing (+)-cam and (−)-cam.

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