Weak interactions and their impact on cellulose dissolution in an alkali/urea aqueous system

2017 ◽  
Vol 19 (27) ◽  
pp. 17909-17917 ◽  
Author(s):  
Sen Wang ◽  
Peng Sun ◽  
Maili Liu ◽  
Ang Lu ◽  
Lina Zhang
Keyword(s):  
Physical Chemistry ◽  
Weak Interactions ◽  
Aqueous System ◽  
Cellulose Dissolution ◽  
System P ◽  
Non Covalent Interactions ◽  
Covalent Interactions

This work exhibited the indispensability and significance of weak non-covalent interactions between urea and macromolecules in a sophisticated physical chemistry process.

scholarly journals Weak Interactions in Cocrystals of Isoniazid with Glycolic and Mandelic Acids

Crystals ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 328
Author(s):  
Raquel Álvarez-Vidaurre ◽  
Alfonso Castiñeiras ◽  
Antonio Frontera ◽  
Isabel García-Santos ◽  
Diego M. Gil ◽  
...  
Keyword(s):  
Density Functional ◽  
Glycolic Acid ◽  
Weak Interactions ◽  
Three Dimensional ◽  
Functional Theory ◽  
Molecular Systems ◽  
X Ray Crystallography ◽  
Hydroxycarboxylic Acids ◽  
Non Covalent Interactions ◽  
Covalent Interactions

This work deals with the preparation of pyridine-3-carbohydrazide (isoniazid, inh) cocrystals with two α-hydroxycarboxylic acids. The interaction of glycolic acid (H2ga) or d,l-mandelic acid (H2ma) resulted in the formation of cocrystals or salts of composition (inh)·(H2ga) (1) and [Hinh]+[Hma]–·(H2ma) (2) when reacted with isoniazid. An N′-(propan-2-ylidene)isonicotinic hydrazide hemihydrate, (pinh)·1/2(H2O) (3), was also prepared by condensation of isoniazid with acetone in the presence of glycolic acid. These prepared compounds were well characterized by elemental analysis, and spectroscopic methods, and their three-dimensional molecular structure was determined by single crystal X-ray crystallography. Hydrogen bonds involving the carboxylic acid occur consistently with the pyridine ring N atom of the isoniazid and its derivatives. The remaining hydrogen-bonding sites on the isoniazid backbone vary based on the steric influences of the derivative group. These are contrasted in each of the molecular systems. Finally, Hirshfeld surface analysis and Density-functional theory (DFT) calculations (including NCIplot and QTAIM analyses) have been performed to further characterize and rationalize the non-covalent interactions.

scholarly journals Supramolecular interactions between catalytic species allow rational control over reaction kinetics

2019 ◽  
Vol 10 (39) ◽  
pp. 9115-9124 ◽  
Author(s):  
Abraham J. P. Teunissen ◽  
Tim F. E. Paffen ◽  
Ivo A. W. Filot ◽  
Menno D. Lanting ◽  
Roy J. C. van der Haas ◽  
...  
Keyword(s):  
Dft Calculations ◽  
Reaction Kinetics ◽  
Phase Transfer ◽  
Supramolecular Interactions ◽  
Two Phase ◽  
Phase Transfer Catalysts ◽  
System P ◽  
Non Covalent Interactions ◽  
Rational Control ◽  
Covalent Interactions

The non-covalent interactions between two phase-transfer catalysts allow tuning of reaction kinetics from bimolecular, to pseudo 0th order, to sigmoidal. Kinetic models and DFT calculations are used to obtain detailed insight in the system.

scholarly journals Controlling hydrogel properties by tuning non-covalent interactions in a charge complementary multicomponent system

2021 ◽  
Author(s):  
Santanu Panja ◽  
Annela Seddon ◽  
Dave Adams
Keyword(s):  
Small Molecule ◽  
Multicomponent System ◽  
System P ◽  
Non Covalent Interactions ◽  
The Individual ◽  
A Charge ◽  
Covalent Interactions

Mixing small molecule gelators is a promising route to prepare useful and exciting materials that cannot be accessed from any of the individual components. Here, we describe pH-triggered hydrogelation by...

scholarly journals Exploration of Weak Interactions in Penta-Substituted Cyclohexanol: Crystal Structure and DFT study

2021 ◽  
Vol 1 (1) ◽  
pp. 1-11
Author(s):  
Sudipta Pathak ◽  
◽  
Shibashis Halder ◽  
Malay Dolai ◽  
Saugata Konar ◽  
...  
Keyword(s):  
Crystal Packing ◽  
Weak Interactions ◽  
Geometry Optimization ◽  
Solvent Mixture ◽  
Dft Study ◽  
Supramolecular Framework ◽  
X Ray ◽  
Bonding Interaction ◽  
Non Covalent Interactions ◽  
Covalent Interactions

During attempts to produce penta-substituted cyclohexanol involving weak interactions, we have crystallized A [where, A = (1S,2S,3R,4S,6S)-2,6-bis(4-bromrophenyl)-4-hydroxy-4-(pyridin- 2-yl)cyclohexane-1,3-diyl)-bis(pyridin-2-ylmethanone)] in DMF-water (1 : 1) solvent mixture with the P-1 space group. Interestingly, in this class of compound, weak interactions have not been explored elaborately in the literature. Herein, we have investigated various types of weak interactions like π · · · π interaction, C–H · · · π interaction, Br· · · Br interaction and H-bonding interaction. These types of non-covalent interactions attribute to the supramolecular framework in the crystal packing of the studied molecule. In addition, the composition of the organic molecule A is confirmed from Single crystal X-ray structure and then performed the theoretical geometry optimization (DFT study) on it.

scholarly journals Manifold Dynamic Non-Covalent Interactions for Steering Molecular Assembly and Cyclization

2021 ◽  
Author(s):  
Shaotang Song ◽  
Lulu Wang ◽  
Jie Su ◽  
Zhen Xu ◽  
Chia-Hsiu Hsu ◽  
...  
Keyword(s):  
Weak Interactions ◽  
Search Algorithm ◽  
Lone Pair ◽  
Molecular Assembly ◽  
Coupling Reactions ◽  
Chemical Transformations ◽  
Quantum Chemistry Calculations ◽  
Non Covalent Interactions ◽  
Molecular Architectures ◽  
Covalent Interactions

Abstract Deciphering rich non-covalent interactions that govern many chemical and biological processes is crucial for the design of drugs and controlling molecular assemblies and their chemical transformations. However, real-space characterization of these weak interactions in complex molecular architectures at single bond level has been a longstanding challenge. Here, we employed bond-resolved scanning probe microscopy combined with an exhaustive structural search algorithm and quantum chemistry calculations to elucidate multiple non-covalent interactions that control the cohesive molecular clustering of a well-design precursor and their chemical reactions. The presence of two flexible bromo-triphenyl moieties in precursor leads to the assembly of distinct non-planar dimer and trimer clusters by manifold non-covalent interactions, including hydrogen bonding, halogen bonding, C − H···π and lone pair···π interactions. The dynamic nature of weak interactions allows for transforming dimers into energetically more favourable trimers as molecular density increases. The formation of trimers also facilitates thermally-triggered intermolecular Ullman coupling reactions, while the disassembly of dimers favours intramolecular cyclization, as evidenced by bond-resolved imaging of metalorganic intermediates and final products. The richness of manifold non-covalent interactions offers unprecedented opportunities for controlling the assembly of complex molecular architectures and steering on-surface synthesis of quantum nanostructures.

NON COVALENT INTERACTIONS IN LARGE DIAMONDOID DIMERS IN THE GAS PHASE - A MICROWAVE STUDY

2017 ◽  
Author(s):  
Cristobal Perez ◽  
Melanie Schnell ◽  
Peter Schreiner ◽  
Norbert Mitzel ◽  
Yury Vishnevskiy ◽  
...  
Keyword(s):  
Gas Phase ◽  
Non Covalent Interactions ◽  
Covalent Interactions

Vapour Pressure Isotope Effect on Evaporation from Pure Organic Phases - a PIMD Approach

2020 ◽  
Author(s):  
Luis Vasquez ◽  
Agnieszka Dybala-Defratyka
Keyword(s):  
Path Integral ◽  
Vapour Pressure ◽  
Density Functional ◽  
Isotope Effects ◽  
Tight Binding ◽  
Decomposition Analysis ◽  
Energy Decomposition Analysis ◽  
Special Importance ◽  
Non Covalent Interactions ◽  
Covalent Interactions

<p></p><p>Very often in order to understand physical and chemical processes taking place among several phases fractionation of naturally abundant isotopes is monitored. Its measurement can be accompanied by theoretical determination to provide a more insightful interpretation of observed phenomena. Predictions are challenging due to the complexity of the effects involved in fractionation such as solvent effects and non-covalent interactions governing the behavior of the system which results in the necessity of using large models of those systems. This is sometimes a bottleneck and limits the theoretical description to only a few methods.<br> In this work vapour pressure isotope effects on evaporation from various organic solvents (ethanol, bromobenzene, dibromomethane, and trichloromethane) in the pure phase are estimated by combining force field or self-consistent charge density-functional tight-binding (SCC-DFTB) atomistic simulations with path integral principle. Furthermore, the recently developed Suzuki-Chin path integral is tested. In general, isotope effects are predicted qualitatively for most of the cases, however, the distinction between position-specific isotope effects observed for ethanol was only reproduced by SCC-DFTB, which indicates the importance of using non-harmonic bond approximations.<br> Energy decomposition analysis performed using the symmetry-adapted perturbation theory (SAPT) revealed sometimes quite substantial differences in interaction energy depending on whether the studied system was treated classically or quantum mechanically. Those observed differences might be the source of different magnitudes of isotope effects predicted using these two different levels of theory which is of special importance for the systems governed by non-covalent interactions.</p><br><p></p>

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