Volumetric, Viscometric, and1H NMR Studies on Caffeine, Theophylline, and Theobromine in Aqueous Solutions of MgCl2at TemperaturesT= (288.15 to 318.15) K and at Pressurep= 101.3 kPa

2017 ◽  
Vol 62 (11) ◽  
pp. 3833-3847 ◽  
Author(s):  
Tarlok S. Banipal ◽  
Aashima Beri ◽  
Parampaul K. Banipal
Keyword(s):  
Aqueous Solutions ◽  
Nmr Studies

scholarly journals 1H NMR Studies of Surfactants in Aqueous Solutions

2003 ◽  
Vol 19 (07) ◽  
pp. 675-680 ◽  
Author(s):  
Mao Shi-Zhen ◽  
◽  
Du You-Ru
Keyword(s):  
Aqueous Solutions ◽  
Nmr Studies ◽  
H Nmr

17O and 183W NMR studies of the paratungstate anions in aqueous solutions

Polyhedron ◽  
1985 ◽  
Vol 4 (9) ◽  
pp. 1559-1562 ◽  
Author(s):  
R.I. Maksimovskaya ◽  
K.G. Burtseva
Keyword(s):  
Aqueous Solutions ◽  
Nmr Studies

Beryllium Coordination to Bio-Ligands: Isolation from Aqueous Solution and Crystal Structure of a Hexanuclear Complex of Be2+ with Glycolic Acid, Na4[Be6(OCH2CO2)8]

1992 ◽  
Vol 47 (12) ◽  
pp. 1717-1720 ◽  
Author(s):  
O. Kumberger ◽  
J. Riede ◽  
H. Schmidbaur
Keyword(s):  
Aqueous Solutions ◽  
Glycolic Acid ◽  
Complexing Agents ◽  
Hydroxyl Groups ◽  
X Ray Diffraction ◽  
Nmr Studies ◽  
X Ray ◽  
Biological Substrates ◽  
Complex Features ◽  
Hexanuclear Complex

Beryllium and its compounds are highly toxic to most living cells, but the mechanisms of the interference with the biological substrates on the molecular level is not understood. From observations in (attempted) chemotherapy of beryllium poisoning using a variety of complexing agents it has been concluded that Be2+ is interacting predominantly with carboxyl as well as hydroxyl functions of protein bio-polymers, with complete deprotonation of the alkoxy or phenoxy functions involved. As a first support for this hypothesis, an analytically well-defined beryllium complex of glycolic acid has now been isolated from aqueous solutions under nearphysiological conditions, crystallized and its structure determined by X-ray diffraction. The hexanuclear complex features beryllium in two different environments, mono- and bis-chelated by glycolate ligands with deprotonated hydroxyl groups. In 9Be-NMR studies of aqueous solutions of the complex (pH 6) the persistence of complexation in two different environments of Be2+ could also be confirmed. The new structure may serve as a model for beryllium complexation with larger bio-ligands.

scholarly journals Molecular recognition of N-acetyltryptophan enantiomers by β-cyclodextrin

2017 ◽  
Vol 13 ◽  
pp. 1572-1582 ◽  
Author(s):  
Spyros D Chatziefthimiou ◽  
Mario Inclán ◽  
Petros Giastas ◽  
Athanasios Papakyriakou ◽  
Konstantina Yannakopoulou ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Molecular Recognition ◽  
Aqueous Solutions ◽  
Crystalline State ◽  
Dimeric Complex ◽  
Nmr Studies ◽  
Guest Molecules ◽  
Crystallographic Order

The enantioselectivity of β-cyclodextrin (β-CD) towards L- and D-N-acetyltryptophan (NAcTrp) has been studied in aqueous solution and the crystalline state. NMR studies in solution show that β-CD forms complexes of very similar but not identical geometry with both L- and D-NAcTrp and exhibits stronger binding with L-NAcTrp. In the crystalline state, only β-CD–L-NAcTrp crystallizes readily from aqueous solutions as a dimeric complex (two hosts enclosing two guest molecules). In contrast, crystals of the complex β-CD–D-NAcTrp were never obtained, although numerous conditions were tried. In aqueous solution, the orientation of the guest in both complexes is different than in the β-CD–L-NAcTrp complex in the crystal. Overall, the study shows that subtle differences observed between the β-CD–L,D-NAcTrp complexes in aqueous solution are magnified at the onset of crystallization, as a consequence of accumulation of many soft host–guest interactions and of the imposed crystallographic order, thus resulting in very dissimilar propensity of each enantiomer to produce crystals with β-CD.

NMR Studies of the Equilibria and Reaction Rates in Aqueous Solutions of Formaldehyde

2015 ◽  
Vol 119 (12) ◽  
pp. 4479-4487 ◽  
Author(s):  
Michal Rivlin ◽  
Uzi Eliav ◽  
Gil Navon
Keyword(s):  
Aqueous Solutions ◽  
Reaction Rates ◽  
Nmr Studies
Sign in / Sign up

Export Citation Format

Share Document