Rotational isomerism of the amide units in rotaxanes based on a cyclic tetraamide and secondary ammonium ions

2019 ◽  
Vol 6 (7) ◽  
pp. 1002-1009 ◽  
Author(s):  
Yukari Okuma ◽  
Toshihiro Tsukamoto ◽  
Takayuki Inagaki ◽  
Shinobu Miyagawa ◽  
Masaki Kimura ◽  
...  
Keyword(s):  
Rotational Isomerism ◽  
Conformational Isomerism ◽  
Ammonium Ions

We describe the synthesis of [2]rotaxanes consisting of a macrocyclic tetraamide and mono- and bis-ammonium ions and their conformational isomerism.

Rotational isomerism in fluorene derivatives. XX. Conformational equilibria of 9-substituted 9-(o-methylthiomethylphenyl)- and 9-substituted 9-(o-methylsulfinylmethylphenyl)fluorenes

1991 ◽  
Vol 69 (4) ◽  
pp. 615-619 ◽  
Author(s):  
Akiko Nishida ◽  
Yoshifumi Akagawa ◽  
Shinsuke Shirakawa ◽  
Shizuo Fujisaki ◽  
Shoji Kajigaeshi
Keyword(s):  
Low Temperature ◽  
Key Words ◽  
Equilibrium Constant ◽  
Internal Rotation ◽  
Kinetic Data ◽  
Room Temperature ◽  
Rotational Isomerism ◽  
Oxidation Products ◽  
Conformational Isomerism ◽  
Conformational Equilibria

Several 9-substituted 9-(o-methylthiomethylphenyl)fluorenes and their oxidation products, 9-substituted 9-(o-methylsulfinylmethylphenyl)fluorenes, were prepared. Each equilibrium constant at room temperature or at low temperature was investigated and the conformational equilibria [Formula: see text] of these compounds are discussed by comparing them with those of the corresponding 9-substituted 9-(o-methylthiophenyl)fluorenes and 9-substituted 9-(o-methylsulfinylphenyl)fluorenes in which the o-substituents were one CH2 unit shorter than those of the title compounds. Kinetic data for the internal rotation of several compounds are also given. Key words: conformational isomerism, restricted rotation, 9-arylfluorenes.

ALDOSTERONE STIMULATION IN VITRO

1965 ◽  
Vol 50 (2) ◽  
pp. 301-309 ◽  
Author(s):  
Jürg Müller
Keyword(s):  
Ammonium Chloride ◽  
Human Urine ◽  
Incubation Medium ◽  
The Other ◽  
Ammonium Ions ◽  
Response Curves ◽  
Urine Extract ◽  
Similar Dose ◽  
Aldosterone Production

ABSTRACT An extract of human urine, which was previously shown to stimulate aldosterone production by rat adrenal sections, was further purified. Evidence was obtained that its aldosterone-stimulating effect was due to the presence of ammonium ions. Addition of ammonium chloride and of urine extract to the incubation medium caused identical increases in aldosterone production in vitro. In addition to ammonium ions, rubidium and caesium ions also stimulated aldosterone production up to 250% that of control values without a significant effect on corticosterone production. Similar dose-response curves were obtained when increasing concentrations of potassium, ammonium, rubidium and caesium ions were tested. Aldosterone production was maximal at concentrations of 7 mval/1 and was significantly lower at higher concentrations. When ammonium chloride and ACTH were simultaneously added to the incubation medium, the production of aldosterone and of corticosterone was lower than with ACTH alone. On the other hand, the stimulating activity on aldosterone and corticosterone production by »TPN« (NADP) and glucose-6-phosphate was enhanced by the simultaneous addition of ammonium chloride.

Sorption of Heavy Metals by Bed Silts in the Presence of Ammonium Ions

2016 ◽  
Vol 38 (2) ◽  
pp. 96-100
Author(s):  
V. Shkapenko ◽  
V. Kadoshnikov ◽  
E. Musich ◽  
I. Pisanskaya
Keyword(s):  
Heavy Metals ◽  
Ammonium Ions

Ground water quality of selected areas of Punjab and Sind Provinces, Pakistan: Chemical and microbiological aspects

2019 ◽  
Author(s):  
Chem Int
Keyword(s):  
Ionic Concentration ◽  
Chloride Ions ◽  
Potassium Ions ◽  
Ammonium Ions ◽  
High Concentration ◽  
Phosphate Ions ◽  
Sodium Magnesium ◽  
Very High ◽  
Microbiological Aspects

The assessment of groundwater is essential for the estimation of suitability of water for safe use. An attempt has been made to study the groundwater of selected areas of Punjab (Sheikhupura & Sahiwal) and Sindh (Sindh, Jawar Dharki and Dharki), Pakistan. The results indicate that pH, color and odor were all within limits of WHO that is pH ranges 6.5–8.5, colorless and odorless, respectively. The high values of suspended solids were observed in the Sindh-1 and Dharki samples. Microbiologically only Sahiwal and Jawar Dharki were found fit for drinking purpose. Trace metals analysis of Sheikhupura-1 and Sindh-1 showed that values do not fall within limits of WHO for Iron. The ionic concentration analysis showed that high bicarbonate (HCO3-), ions are present in the samples of Sahiwal and Dharki; Sindh-1 and Jawar Dharki samples showed very high concentration for chloride ions, all samples were satisfactory level for sulphate (SO42-), sodium, magnesium and phosphate ions except samples of Sindh-1 and Jawar Dharki. High concentration of calcium and potassium ions was observed in samples of Sindh-1, while all other samples were found fit for drinking purposes in respect of nitrate, nitrite and ammonium ions. The high concentration of Fluoride was found only in Sheikhupura-2 samples.

Photophysical Characterisation, Metal Ion Binding and Enantiomeric Recognition of Chiral Ligands Containing Phenazine Fluorophore

2004 ◽  
Vol 69 (4) ◽  
pp. 885-896 ◽  
Author(s):  
Luisa Stella Dolci ◽  
Péter Huszthy ◽  
Erika Samu ◽  
Marco Montalti ◽  
Luca Prodi ◽  
...  
Keyword(s):  
Metal Ion ◽  
Photophysical Properties ◽  
Ion Binding ◽  
Metal Ion Binding ◽  
Ammonium Ions ◽  
Enantiomerically Pure ◽  
Binding Process ◽  
High Affinity ◽  
Enantiomeric Recognition ◽  
Chiral Species

Enantiomerically pure dimethyl- and diisobutyl-substituted phenazino-18-crown-6 ligands bind metal and ammonium ions and also primary aralkylammonium perchlorates in acetonitrile with high affinity, causing pronounced changes in their luminescence properties. In addition, they show enantioselectivity towards chiral primary aralkylammonium perchlorates. The possibility to monitor the binding process by photoluminescence spectroscopy can gain ground for the design of very efficient enantioselective chemosensors for chiral species. The observed changes in the photophysical properties are also an important tool for understanding the interactions present in the adduct.

Conformational isomerism of the seven-membered heterocycle in a single crystal of [η2-Ph2P(O)(CH2)2C(O)NМе2]TiF4 adduct

2016 ◽  
Vol 470 (1) ◽  
pp. 255-259 ◽  
Author(s):  
E. G. Il’in ◽  
A. S. Parshakov ◽  
G. G. Aleksandrov ◽  
V. G. Yarzhemskii ◽  
V. V. Danilov ◽  
...  
Keyword(s):  
Single Crystal ◽  
Conformational Isomerism ◽  
Membered Heterocycle

Raman Spectra of Solid (NH4)2CrO4 and (ND4)2CrO4 Obtained by a Rotating Cell Technique

1976 ◽  
Vol 30 (2) ◽  
pp. 187-190 ◽  
Author(s):  
Robert L. Carter ◽  
L. Kevin O'Hare
Keyword(s):  
Hydrogen Bonding ◽  
Alkali Metal ◽  
Raman Spectra ◽  
Sampling Technique ◽  
Solid Sampling ◽  
Monoclinic Structure ◽  
Ammonium Ions ◽  
Cylindrical Cell ◽  
Sample Rotation ◽  
Rotation Technique

The Raman spectra of polycrystalline (NH4)2CrO4 and (ND4)2CrO4 have been obtained by a sample rotation technique where the uncompressed solid is contained in a glass cylindrical cell. The apparatus is a commerically available sample rotator for liquids, which was modified for the described solid sampling technique. The Raman spectra of (NH4)2CrO4 and (ND4)2CrO4 are discussed in relation to their uniquely monoclinic structure, in contrast to the β-K2SO4 structure found for (NH4)2SO4 and many alkali metal chromates and sulfates. The hydrogen bonding in (NH4)2CrO4 is described, and its role in determining both the structure and the Raman spectra is discussed. The data suggest a barrier to NH4+ rotation of approximately 3.70 kcal/mol, indicating that the ammonium ions are not freely rotating on the time scale of the Raman experiment (10−13 sec).

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