Etude spectroscopique des dérivés du peroxyde d'hydrogène. IV. L'acide de Caro, H2SO5

1970 ◽  
Vol 48 (24) ◽  
pp. 3903-3910 ◽  
Author(s):  
José L. Arnau ◽  
Paul A. Giguère
Keyword(s):  
Hydrogen Bonding ◽  
Hydrogen Bonds ◽  
Intramolecular Hydrogen Bonding ◽  
Hydroxyl Groups ◽  
Intermolecular Hydrogen Bonds ◽  
Laser Raman ◽  
Laser Raman Spectra ◽  
Intramolecular Hydrogen ◽  
First Time ◽  
Lattice Modes

The i.r. and laser Raman spectra of pure, crystalline Caro's acid, H2SO5, were measured for the first time between 4000 and 30 cm−1. Most of the fundamental vibrations of the molecule could be identified by comparison with those of the H2SO4, H2O2 and HSO5− species. In addition, a dozen or so of lattice modes were recorded. The O—O stretching frequency is slightly higher (886 cm−1) than in solid H2O2, contrary to expectation. The two hydroxyl groups are quite different, both chemically (Caro's acid is essentially monobasic) and spectroscopically. The ionizable OH group forms strong intermolecular hydrogen bonds, as in H2SO4. However, the non-ionizable O2H group is engaged mainly in intramolecular hydrogen bonding. The unit cell of the crystalline acid must contain more than two molecules.

Synthesis of 2', 6'-Dihydroxychalcones by Using Tetrahydropyran-2-yl and Trialkylsilyl Protective Groups; the Crystal Structure Determination of 2',6'-Dihydroxy-2,4,6-trimethoxychalcone

1989 ◽  
Vol 42 (7) ◽  
pp. 1103 ◽  
Author(s):  
CO Miles ◽  
L Main ◽  
BK Nicholson
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bonding ◽  
Intramolecular Hydrogen Bonding ◽  
Silyl Ether ◽  
X Ray ◽  
Protective Groups ◽  
Intramolecular Hydrogen ◽  
First Time ◽  
Mild Acid

Two improved general routes to 2′,6′-dihydroxychalcones are described in which the final step is protective-group removal from O 2′ under mild acid conditions. The first involves base-catalysed condensation of benzaldehydes with 2′-hydroxy-6′-tetrahydropyran-2-yloxyacetophenone, the second ring-opening of 5-hydroxyflavanones with 1,8-diazabicyclo[5.4.0]undec-7-ene in the presence of a trialkylchlorosilane to trap out the chalcone as a bis silyl ether. Chalcones prepared by the first route are 2',6'-dihydroxychalcone (1), and its 4-methoxy (2), 3,4-dimethoxy (3), 3,4,5-trimethoxy (4), and 2,4,6-trimethoxy (5) derivatives. The 4-chloro derivative (6) and the chalcone from hesperetin are prepared by the second method. .The X-ray crystal structure of 2',6'-dihydroxy-2,4,6-trimethoxychalcone (5), the first for a 2',6′-dihydroxychalcone, is reported, the hydrogen involved in intramolecular hydrogen-bonding between the carbonyl and phenolic oxygens being located for the first time for any 2'-hydroxychalcone derivative. The O 6' involved in the intramolecular hydrogen-bonding is also hydrogen-bonded intermolecularly to the hydrogen of the other (2'-)hydroxy group of a neighbouring molecule in the lattice. 13C n.m.r. data are the first reported for a series of 2',6'-dihydroxychalcones.

scholarly journals Deprotonation of resorcinarenes and novel ammonium salt complexes

2014 ◽  
Vol 70 (a1) ◽  
pp. C678-C678
Author(s):  
Ngong Beyeh ◽  
Arto Valkonen ◽  
Fanfang Pan ◽  
Kari Rissanen
Keyword(s):  
Hydrogen Bonds ◽  
Binding Sites ◽  
Molecular Complexes ◽  
Ammonium Salts ◽  
Hydroxyl Groups ◽  
Binding Modes ◽  
Intermolecular Hydrogen Bonds ◽  
Guest Molecules ◽  
Cone Conformation ◽  
Intramolecular Hydrogen

The bowl shape cavity of resorcinarenes usually stabilized by four intramolecular hydrogen bonds offers an interesting array of binding modes such as C–H...π and cation...π interactions to recognize a variety of guests. The multiple hydroxyl groups can participate in a series of intermolecular hydrogen bonds with guest molecules. This unique cone conformation of resorcinarenes has led to the synthesis of many receptors with convergent arrangement of binding sites suitable for molecular recognition in many applications. Unfunctionalized resorcinarenes are known to easily form molecular complexes with guests of varying shapes and sizes. Amines are very common bases used in many catalytic processes. A good example is the use of amines as bases in the alkylation and acylation of resorcinarenes leading to cavitands, carcerands, hemicarcerands and velcrands. The use of amines in such reactions is to deprotonate the resorcinarene hydroxyl groups, hence facilitating the alkylation and acylation processes. The subsequently protonated ammonium cation then forms interesting supramolecular complexes with the anionic and dianionic resorcinarenes. Furthermore, secondary and tertiary ammonium salts possess hydrogen bond donating -NH2 and -NH respectively and these can further enhance their complexation through intermolecular hydrogen bonds. Here we present our recent examples of supramolecular assemblies resulting from the deprotonation of resorcinarenes by mono- and dibasic amines. Also, our latest supramolecular co-crystals between resorcinarenes as the receptors and a series of secondary and tertiary mono- and diammonium cations are illustrated.

Synthesis, molecular packing and anti-cholinesterase activity of some new C-2 N-substituted anthranilamide derivatives

2019 ◽  
Vol 234 (9) ◽  
pp. 605-611 ◽  
Author(s):  
Muhammad Sarfraz ◽  
Nargis Sultana ◽  
Muhammad Ilyas Tariq ◽  
Masood Parvez
Keyword(s):  
Hydrogen Bonding ◽  
Cholinesterase Activity ◽  
Intramolecular Hydrogen Bonding ◽  
Pharmacokinetic Profile ◽  
Intermolecular Hydrogen Bonds ◽  
Standard Drug ◽  
X Ray ◽  
Hydrogen Bonding Interactions ◽  
Intramolecular Hydrogen

Abstract Synthesis of C-2 N-substituted anthranilamide derivatives was carried out in a straight forward manner, utilizing 2-aminobenzamide and benzyl chloride as starting materials. Their crystal structures have been established by single crystal X-ray crystallographic method. In the molecules of 2-benzylamino-benzamide (3a), intramolecular hydrogen bonding b/w O atom and proton of –NH and classical intermolecular hydrogen bonding of the type N–H · · · O forming eight membered rings in R42(8) pattern. In both molecules of 2-(dibenzylamino)benzamide (3b), unlike the molecule in 3a, each H atoms is pointed towards N atom causing intramolecular hydrogen bonding interactions, resulting in S(6) motifs. However, it is interesting to note that both molecules in 3b are lying about inversion centres and form dimers in R42(8) motifs; the two dimers are linked via non-classical intermolecular hydrogen bonds C–H · · · O resulting in clusters of four molecules in the structure. In vitro assay results revealed that molecule 3b with IC50 values of 3.8 ± 0.08 μM (AChE) and 17.6 ± 1.10 μM (BChE) possessed better cholinesterase (AChE and BChE) inhibition potential as compared to standard drug galantamine. Preliminary in silico studies showed that more biological active derivatives were also having good pharmacokinetic profile with no AMES toxicity and carcinogenicity.

scholarly journals Intramolecular Hydrogen Bonding 2021

Molecules ◽  
2021 ◽  
Vol 26 (20) ◽  
pp. 6319
Author(s):  
Mirosław Jabłoński
Keyword(s):  
Hydrogen Bonding ◽  
Hydrogen Bonds ◽  
Intermolecular Interactions ◽  
Intramolecular Hydrogen Bonding ◽  
The Rich ◽  
Intramolecular Hydrogen

Undoubtedly, hydrogen bonds occupy a leading place in the rich world of intermolecular interactions [...]

scholarly journals Intramolecular N–H⋯Cl hydrogen bonds in the outer coordination sphere of a bipyridyl bisurea-based ligand stabilize a tetrahedral FeLCl2 complex

2014 ◽  
Vol 50 (54) ◽  
pp. 7173-7175 ◽  
Author(s):  
Jesse V. Gavette ◽  
Christina M. Klug ◽  
Lev N. Zakharov ◽  
Matthew P. Shores ◽  
Michael M. Haley ◽  
...  
Keyword(s):  
Hydrogen Bonding ◽  
Hydrogen Bonds ◽  
Coordination Sphere ◽  
Intramolecular Hydrogen Bonding ◽  
Secondary Coordination Sphere ◽  
Chloride Ligands ◽  
Outer Coordination Sphere ◽  
Intramolecular Hydrogen

A bipyridyl-bisurea ligand coordinates a tetrahedral FeCl2 complex and demonstrates secondary coordination sphere influence through intramolecular hydrogen bonding to the chloride ligands.

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