scholarly journals Investigation of the nature of hydrogen bonds in 3,5-dimethylpyrazole

2020 ◽  
Vol 61 (1) ◽  
pp. 9-13
Author(s):  
Tatiana G. Volkova ◽  
◽  
Konstantin A. Chicherin ◽  
Irina O. Talanova ◽  
◽  
...  
Keyword(s):  
Hydrogen Bond ◽  
Hydrogen Bonds ◽  
Self Organization ◽  
Supramolecular Systems ◽  
Acceptor Interaction ◽  
Covalent Interaction ◽  
Wide Range ◽  
Main Motive ◽  
Donor Acceptor ◽  
Hydrogen Bound

Compounds containing a pyrazole fragment in their structure are part of many medicines and have a wide range of bioactivity (for example, antimicrobial, anti-tuberculosis, etc.), and are also successfully used for the development of various synthetic anti-tumor agents. Interest in them is also caused by the presence of hydrogen bonds, which are the main motive for self-organization of molecules. A theoretical study of the nature of hydrogen bonds in various hydrogen-bound motifs in 3,5-dimethylpyrazole was performed using the DFT/B3LYP/6-31G(d,p) method. The results obtained indicate the possible existence of dimeric, trimeric, and tetrameric cyclic forms. Geometric and energy parameters of hydrogen bonds N-H...N are determined and the energies of donor-acceptor interaction in possible forms of self-organization of the molecules of the studied compound are calculated. It has been established that the hydrogen bond (H-bond) is the result of the interaction of a hybrid unshielded pair of a nitrogen atom of one molecule and a loosening natural orbital between the nitrogen atoms of one molecule and the hydrogen of another molecule (σ* N-H). The formation of the binding σ-orbital of the H-bond indicates the predominance of covalent interaction in the hydrogen bond. The study and analysis of the results showed that the formation of supramolecular systems of 3,5-dimethylpyrazole most likely structures are trimers and tetramers.

The Influence of Small Monovalent Cations on Neighbouring Hydrogen Bonds of Aquo-Protein Complexes

1981 ◽  
Vol 36 (12) ◽  
pp. 1357-1360 ◽  
Author(s):  
Kritsana P. Sagarik ◽  
Bernd M. Rode
Keyword(s):  
Hydrogen Bond ◽  
Hydrogen Bonds ◽  
Metal Ion ◽  
Protein Complexes ◽  
Basis Sets ◽  
Monovalent Cations ◽  
Hydrogen Bond Energy ◽  
Acceptor Interaction ◽  
Monovalent Metal ◽  
Donor Acceptor

AbstractThe influence of small monovalent metal ions on hydrogen bonds of aquo-protein complexes is studied on Li+/HCONH2-OH2 as an example. Using results obtained from ab initio calculations with minimal GLO basis sets, the remarkable changes in the hydrogen bond energy and charge distribution, due to metal ion complex formation, are discussed. The metal ion seems to enhance strongly the donor-acceptor interaction of the O ... H-N-C=0 hydrogen-bonded system.

On the Hydrogen Bond Breaking Ability of Fluorocarbons Containing Higher Halogens

1974 ◽  
Vol 52 (21) ◽  
pp. 3612-3622 ◽  
Author(s):  
Thérèse Di Paolo ◽  
C. Sandorfy
Keyword(s):  
Hydrogen Bond ◽  
Hydrogen Bonds ◽  
Bond Breaking ◽  
Anesthetic Activity ◽  
Competitive Mechanism ◽  
Infrared Measurements ◽  
Donor Acceptor

Infrared measurements show that fluorocarbons containing higher halogens are able to open O—H---O, N—H---N, S—H---S, N—H---O=C, type hydrogen bonds. This is probably due to a competitive mechanism of association consisting in the formation of donor–acceptor complexes. It is suggested that the breaking or perturbation of hydrogen bonds by this mechanism is of importance for the explanation of the anesthetic activity of these compounds.

Asymptotic Strength Limit of Hydrogen Bond Assemblies in Proteins at Vanishing Pulling Rates

2007 ◽  
Vol 1062 ◽  
Author(s):  
Sinan Keten ◽  
Markus J. Buehler
Keyword(s):  
Hydrogen Bond ◽  
Hydrogen Bonds ◽  
Computational Studies ◽  
Entropic Elasticity ◽  
Strength Limit ◽  
Wide Range ◽  
Peptide Hydrogen ◽  
Polypeptide Chains ◽  
Limiting Value ◽  
Intrinsic Strength

ABSTRACTExperimental and computational studies on mechanical unfolding of proteins suggest that rupture forces approach a limiting value of a few hundred pN at vanishing pulling velocities. We develop a fracture mechanics based theoretical framework that considers the free energy competition between entropic elasticity of polypeptide chains and rupture of peptide hydrogen bonds, which we use here to provide an explanation for the intrinsic strength limit of proteins. Our analysis predicts that individual protein domains stabilized by hydrogen bonds can not exhibit rupture forces larger than approximately ≈200 pN, regardless of the presence of a large number of hydrogen bonds. This result explains a wide range of experimental and computational observations.

Polymorphs and pseudopolymorphs of N,N′-dithiobisphthalimide

2002 ◽  
Vol 58 (2) ◽  
pp. 289-299 ◽  
Author(s):  
Dorcas M. M. Farrell ◽  
Christopher Glidewell ◽  
John N. Low ◽  
Janet M. S. Skakle ◽  
Choudhury M. Zakaria
Keyword(s):  
Hydrogen Bond ◽  
Hydrogen Bonds ◽  
Solvent Molecule ◽  
Solvent Free ◽  
Stacking Interactions ◽  
Rotation Axes ◽  
Π Stacking ◽  
Wide Range ◽  
Unit Cells ◽  
Solvent Molecules

N,N′-Dithiobisphthalimide, C16H8N2O4S2 (I), forms a wide range of polymorphs and solvates (pseudopolymorphs). When (I) is crystallized from methanol it yields a solvent-free polymorph (4), in Pna21 with Z′ = 1, in which the molecules are linked into chains by a single C—H...O hydrogen bond: crystallization from either acetonitrile or dimethylformamide produces a monoclinic polymorph (5), in P21/c with Z′ = 2, also solvent-free, in which the molecules are linked into molecular ladders. Nitromethane forms a monosolvate, C16H8N2O4S2·CH3NO2 (6), in P21/c with Z′ = 1, in which the solvent molecules are linked to the molecules of (I) not only via a conventional C—H...O hydrogen bond but also via a polarized multicentre interaction involving all three C—H bonds of the solvent molecule. Chlorobenzene forms a precise hemisolvate, C16H8N2O4S2·0.5C6H5Cl (7), in P{\bar 1 } with Z′ = 1, while ethylbenzene forms an approximate hemisolvate 2C16H8N2O4S2·0.913C6H5C2H5·0.087H2O (8), in P21/c with eight molecules of (I) per unit cell. In both solvates the molecules of (I) are linked, in (7) by π...π stacking interactions augmented by weak C—H...O hydrogen bonds and in (8) by stronger C—H...O hydrogen bonds: the solvent molecules lie in isolated cavities, disordered across inversion centres in (7) and fully ordered in general positions in (8). Crystallization of (I) either from tetrahydrofuran or from wet tert-butanol yields isomorphous solvates (9) and (10), respectively, in C2/c with Z′ = 0.5, in which molecules of (I) lie across twofold rotation axes and are linked by π...π stacking interactions and very weak C—H...O hydrogen bonds, forming a framework enclosing continuous channels: highly disordered solvent molecules lie within these channels. p-Xylene and toluene form isomorphous hemisolvates (11) and (12) with unit cells metrically very similar to those of (9) and (10), but in P21/n with Z′ = 1: in these two solvates the molecules of (I) are linked into a framework by very short C—H...O hydrogen bonds; the solvent molecules lie within continuous channels, but they are localized across inversion centres so that the toluene is disordered across an inversion centre.

Reactions between arylhydrazinium chlorides and 2-chloroquinoline-3-carbaldehydes: molecular and supramolecular structures of a hydrazone, a 4,9-dihydro-1H-pyrazolo[3,4-b]quinoline and two 1H-pyrazolo[3,4-b]quinolines

2016 ◽  
Vol 72 (9) ◽  
pp. 670-678 ◽  
Author(s):  
Tholappanavara H. Suresha Kumara ◽  
Gopalpur Nagendrappa ◽  
Nanjappa Chandrika ◽  
Haliwana B. V. Sowmya ◽  
Manpreet Kaur ◽  
...  
Keyword(s):  
Hydrogen Bond ◽  
Hydrogen Bonds ◽  
Biological Activities ◽  
Three Dimensional ◽  
Stacking Interactions ◽  
Compound I ◽  
Space Group ◽  
Π Stacking ◽  
Wide Range ◽  
A Chain

Hydrazone derivatives exhibit a wide range of biological activities, while pyrazolo[3,4-b]quinoline derivatives, on the other hand, exhibit both antimicrobial and antiviral activity, so that all new derivatives in these chemical classes are potentially of value. Dry grinding of a mixture of 2-chloroquinoline-3-carbaldehyde and 4-methylphenylhydrazinium chloride gives (E)-1-[(2-chloroquinolin-3-yl)methylidene]-2-(4-methylphenyl)hydrazine, C17H14ClN3, (I), while the same regents in methanol in the presence of sodium cyanoborohydride give 1-(4-methylphenyl)-4,9-dihydro-1H-pyrazolo[3,4-b]quinoline, C17H15N3, (II). The reactions between phenylhydrazinium chloride and either 2-chloroquinoline-3-carbaldehyde or 2-chloro-6-methylquinoline-3-carbaldehyde give, respectively, 1-phenyl-1H-pyrazolo[3,4-b]quinoline, C16H11N3, (III), which crystallizes in the space groupPbcnas a nonmerohedral twin havingZ′ = 3, or 6-methyl-1-phenyl-1H-pyrazolo[3,4-b]quinoline, C17H13N3, (IV), which crystallizes in the space groupR\overline{3}. The molecules of compound (I) are linked into sheets by a combination of N—H...N and C—H...π(arene) hydrogen bonds, and the molecules of compound (II) are linked by a combination of N—H...N and C—H...π(arene) hydrogen bonds to form a chain of rings. In the structure of compound (III), one of the three independent molecules forms chains generated by C—H...π(arene) hydrogen bonds, with a second type of molecule linked to the chains by a second C—H...π(arene) hydrogen bond and the third type of molecule linked to the chain by multiple π–π stacking interactions. A single C—H...π(arene) hydrogen bond links the molecules of compound (IV) into cyclic centrosymmetric hexamers having \overline{3} (S6) symmetry, which are themselves linked into a three-dimensional array by π–π stacking interactions.

scholarly journals Crystal structure of the 1,3,6,8-tetraazatricyclo[4.3.1.13,8]undecane (TATU)–4-nitrophenol (1/2) adduct: the role of anomeric effect in the formation of a second hydrogen-bond interaction

2015 ◽  
Vol 71 (11) ◽  
pp. 1356-1360 ◽  
Author(s):  
Augusto Rivera ◽  
Héctor Jairo Osorio ◽  
Juan Manuel Uribe ◽  
Jaime Ríos-Motta ◽  
Michael Bolte
Keyword(s):  
Hydrogen Bond ◽  
Hydrogen Bonds ◽  
Three Dimensional ◽  
Normal Donor ◽  
Anomeric Effect ◽  
Hydrogen Bond Interaction ◽  
Hydrogen Bond Formation ◽  
Dimensional Network ◽  
Crystalline Adduct ◽  
Donor Acceptor

In the title ternary co-crystalline adduct, C7H14N4·2C6H5NO3, molecules are linked by two intermolecular O—H...N hydrogen bonds, forming a tricomponent aggregates in the asymmetric unit. The hydrogen-bond formation to one of the N atoms is enough to induce structural stereoelectronic effects in the normal donor→acceptor direction. In the title adduct, the two independent nitrophenol molecules are essentially planar, with maximum deviations of 0.0157 (13) and 0.0039 (13) Å. The dihedral angles between the planes of the nitro group and the attached benzene rings are 4.04 (17) and 5.79 (17)°. In the crystal, aggregates are connected by C—H...O hydrogen bonds, forming a supramolecular dimer enclosing anR66(32) ring motif. Additional C—H...O intermolecular hydrogen-bonding interactions form a second supramolecular inversion dimer with anR22(10) motif. These units are linkedviaC—H...O and C—H...N hydrogen bonds, forming a three-dimensional network.

scholarly journals Sodium sulfite heptahydrate and its relation to sodium carbonate heptahydrate

2020 ◽  
Vol 76 (5) ◽  
pp. 427-432
Author(s):  
Matthias Weil ◽  
Kurt Mereiter
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bond ◽  
Hydrogen Bonds ◽  
Sodium Sulfite ◽  
Monoclinic Crystal ◽  
Organic Sulfur Compounds ◽  
Monoclinic Crystal Structure ◽  
Structural Relationships ◽  
Water Layers ◽  
Donor Acceptor

The monoclinic crystal structure of Na2SO3(H2O)7 is characterized by an alternating stacking of (100) cationic sodium–water layers and anionic sulfite layers along [100]. The cationic layers are made up from two types of [Na(H2O)6] octahedra that form linear 1 ∞[Na(H2O)4/2(H2O)2/1] chains linked by dimeric [Na(H2O)2/2(H2O)4/1]2 units on both sides of the chains. The isolated trigonal–pyramidal sulfite anions are connected to the cationic layers through an intricate network of O—H...O hydrogen bonds, together with a remarkable O—H...S hydrogen bond, with an O...S donor–acceptor distance of 3.2582 (6) Å, which is about 0.05 Å shorter than the average for O—H...S hydrogen bonds in thiosalt hydrates and organic sulfur compounds of the type Y—S—Z (Y/Z = C, N, O or S). Structural relationships between monoclinic Na2SO3(H2O)7 and orthorhombic Na2CO3(H2O)7 are discussed in detail.

scholarly journals Structures and properties of Saturn-like complexes composed of oligothiophene macrocycle with methano[60]fullerene and [70]fullerene

2017 ◽  
Vol 95 (3) ◽  
pp. 315-319 ◽  
Author(s):  
Masahiko Iyoda ◽  
Hideyuki Shimizu ◽  
Shinobu Aoyagi ◽  
Hiroshi Okada ◽  
Biao Zhou ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Solid State ◽  
Acceptor Interaction ◽  
X Ray ◽  
Covalent Interaction ◽  
Structures And Properties ◽  
Fullerene Complexes ◽  
Donor Acceptor ◽  
Short Contacts

π-Expanded oligothienylene macrocycle with a large inner cavity incorporates fullerenes such as methano[60]fullerene (C61H2) and [70]fullerene (C70) inside to form Saturn-like complexes. Although the oligothiophene macrocycle weakly interacts with fullerenes in solution, it forms stable Saturn-like fullerene complexes in the solid state. X-ray analysis of the Saturn-like complexes exhibited short contacts between the sulfur atoms of the oligothiophene macrocycle and fullerene carbons, which hinder the rotation of fullerenes. As a result, the non-covalent interaction between the oligothiophene macrocycle and fullerenes was employed in crystal structure determination of fullerenes. UV–vis–NIR spectra of the Saturn-like complexes showed weak donor–acceptor interaction between the oligothiophene macrocycle and fullerenes.

Photophysics of Fullerene-Doped Nanostructures: Optical Limiting, Hologram Recording and Switching of Laser Beam

2007 ◽  
Vol 555 ◽  
pp. 363-369 ◽  
Author(s):  
Natalie V. Kamanina
Keyword(s):  
Nonlinear Optical ◽  
Charge Transfer Complex ◽  
Self Organization ◽  
High Electron ◽  
Dynamic Parameters ◽  
Hologram Recording ◽  
Acceptor Interaction ◽  
Organic Systems ◽  
High Electron Affinity ◽  
Donor Acceptor

The fullerene-doping effect on spectral, nonlinear optical properties, and dynamic parameters of conjugated organic systems based on pyridine, polyimide, polyaniline, polyvinyl alcohol, liquid crystal, etc. has been studied. Introduction of fullerenes into these materials has been made due to their high electron affinity that allows intermolecular donor-acceptor interaction to be reinforced. The new charge transfer complex provokes new nanostructures potentials such as nonlinear transmission, laser-induced change in the refractive index, self-organization. The application of studied nanostructures in laser and display techniques, and medicine has been discussed.

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