Complexation of the La(III) cation by p-sulfonatocalix[4]arene — A 139La NMR study

2002 ◽  
Vol 80 (2) ◽  
pp. 163-168 ◽  
Author(s):  
Yaël Israëli ◽  
Christine Bonal ◽  
Christian Detellier ◽  
Jean-Pierre Morel ◽  
Nicole Morel-Desrosiers
Keyword(s):  
Linear Relationship ◽  
Standard Enthalpy ◽  
Effective Radius ◽  
Water Soluble ◽  
Water Molecules ◽  
Standard Entropy ◽  
Nmr Data ◽  
Nmr Study ◽  
Good Agreement ◽  
Formation Of Complexes

The complexation of La(III) by the water-soluble p-sulfonatocalix[4]arene was thermodynamically characterized by 139La NMR. The 139La NMR data are consistent with the formation of a 1:1 complex resulting from electro static interactions between the sulfonato groups and La(III). The complexation is entropy-driven and is characterized by a positive standard enthalpy (ΔrH° = 11.0 ± 0.5 kJ mol–1) and a positive standard entropy (ΔrS° = 108 ± 2 J K–1 mol–1), which are in very good agreement with the ones determined previously by microcalorimetry. The linear relationship between the 139La NMR linewidth of the free and of the complexed cation, obtained at temperatures ranging from 290 to 340 K, excludes the formation of complexes or aggregates other than the 1:1 complex. It shows also that upon complexation, the effective radius of La(III) undergoes an increase of 50%, related to the replacement of water molecules of the hydrated cation by sulfonato groups of the ligand.Key words: complexation, water-soluble calixarene, p-sulfonatocalix[4]arene, 139La NMR, lanthanum.

An X-ray and NMR Study on Cerium(III) and Magnesium(II) Perchlorate Solutions

1988 ◽  
Vol 43 (4) ◽  
pp. 317-325 ◽  
Author(s):  
R. Caminiti ◽  
G. Cerioni ◽  
G. Crisponi ◽  
P. Cucca
Keyword(s):  
Complex Formation ◽  
Structural Information ◽  
Coordination Shell ◽  
Water Molecules ◽  
X Ray ◽  
X Ray Scattering ◽  
Nmr Data ◽  
Nmr Study ◽  
Monodentate Ligands ◽  
Good Agreement

Metal-perchlorate solutions have been investigated by the X-ray scattering technique and 35Cl NMR spectroscopy. The aim of this work was to obtain structural information on the complex formation between the Cerium and the Perchlorate group and on the ClO-4 - H2O interactions. The NMR data, the correlation functions and the analysis of the structure functions agree with the literature information about the Ce - (OClO3)z species present in aqueous solutions. Good agreement with experimental data is achieved through a model in which the Perchlorate ions are bonded as monodentate ligands to the Cerium(III). No complex formation is confirmed for Mg(II). The cations also possess a second coordination shell of water molecules. Some indications have been obtained supporting the presence of ClO-4 - H2O contacts.

Determination of the Enantiomeric Excess of Horner Phosphines by 13C NMR Spectroscopy. A 13C and 31P NMR Study of the Diastereomeric Complexes Formed with [η3-(+)(1R,5R )-Pinenyl]nickel Bromide Dimer

1986 ◽  
Vol 41 (1) ◽  
pp. 85-88 ◽  
Author(s):  
Richard Mynott ◽  
Wolf Jürgen Richter ◽  
Günther Wilke
Keyword(s):  
Nmr Spectra ◽  
31P Nmr ◽  
Enantiomeric Excess ◽  
13C Nmr Spectroscopy ◽  
Nmr Data ◽  
Nmr Study ◽  
Diastereomeric Complexes ◽  
13C And 31P Nmr ◽  
Good Agreement

The 13C and 31P NMR data of the Horner phosphines PRR′R″ [R = Me. R′ = t-Bu, R'″ = Ph (2) or i-Pr (4)] and their diastereomeric 1:1 adducts with [η3-(+)(1 R, 5 R)-pinenyI]nickel bromide dimer (3) and (5), respectively, are reported. It is shown that the optical purities of the phosphines can be deduced easily from the NMR spectra. Not only are these values in very good agreement with those obtained from optical rotatory data but they are also obtained much more conveniently.

Glucan isolated from leaves of Althaea officinalis L.

1983 ◽  
Vol 48 (7) ◽  
pp. 2082-2087 ◽  
Author(s):  
Alžbeta Kardošová ◽  
Jozef Rosík ◽  
Rudolf Toman ◽  
Peter Capek
Keyword(s):  
Medicinal Plant ◽  
Periodate Oxidation ◽  
Linear Structure ◽  
Water Soluble ◽  
Partial Hydrolysis ◽  
Methylation Analysis ◽  
Glycosidic Bonds ◽  
Nmr Data ◽  
Althaea Officinalis ◽  
C Nmr

A water-soluble low-molecular D-glucan was isolated from leaves of the medicinal plant marsh-mallow (Althaea officinalis L.). The results of methylation analysis, partial hydrolysis, periodate oxidation, and 13C NMR data indicated a virtually linear structure with α-(1→6) glycosidic bonds.

scholarly journals The Effect of Extraction Conditions on the Barrier and Mechanical Properties of Kefiran Films

Coatings ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 602
Author(s):  
Carmen Rodica Pop ◽  
Teodora Emilia Coldea ◽  
Liana Claudia Salanţă ◽  
Alina Lăcrămioara Nistor ◽  
Andrei Borşa ◽  
...  
Keyword(s):  
Water Vapor ◽  
Conformational Changes ◽  
Water Vapor Permeability ◽  
Edible Films ◽  
Film Structure ◽  
Water Soluble ◽  
Vapor Permeability ◽  
Water Molecules ◽  
Compact Structure ◽  
Technology Applications

Kefiran is an exopolysaccharide classified as a heteropolysaccharide comprising glucose and galactose in equimolar quantities, and it is classified as a water-soluble glucogalactan. This work aimed to investigate the effect of different extraction conditions of kefiran on the structural and physical properties of the edible films obtained. Fourier-transform infrared spectroscopy and scanning electron microscopy were performed, together with a determinations of moisture content, solubility, water vapor permeability and degree of swelling. The kefiran films presented values of the water vapor permeability between 0.93 and 4.38 × 10−11 g/m.s.Pa. These results can be attributed to the development of a more compact structure, where glycerol had no power to increase the free volume and the water vapor diffusion through their structure. The possible conformational changes in the kefiran film structure, due to the interspersing of the plasticizers and water molecules that they absorb, could be the reason for producing flexible kefiran films in the case of using glycerol as a plasticizer at 7.5% w/w. Moreover, it was observed that the extraction conditions are a significant factor in the properties of these films and their food technology applications.

scholarly journals SANS quantification of bound water in water-soluble polymers across multiple concentration regimes

Soft Matter ◽  
2021 ◽  
Author(s):  
Helen Yao ◽  
Bradley D. Olsen
Keyword(s):  
Neutron Scattering ◽  
Small Angle ◽  
Small Angle Neutron Scattering ◽  
Bound Water ◽  
Water Soluble ◽  
Wide Concentration Range ◽  
Water Molecules ◽  
Water Soluble Polymers ◽  
Soluble Polymers

Small-angle neutron scattering is used to measure the number of bound water molecules associating with three polymers over a wide concentration range. Different fitting workflows are evaluated and recommended depending on the concentration regime.

Stereospecific Association of C-20 Epimers of 3β-Hydroxy-16-oxo-24-nor-17-azachol-5-eno-23-nitryle

1997 ◽  
Vol 52 (6) ◽  
pp. 749-756
Author(s):  
Zofia Plesnar ◽  
Stanisław Malanowski ◽  
Zenon Lotowski ◽  
Jacek W. Morzycki ◽  
Jadwiga Frelek ◽  
...  
Keyword(s):  
Proton Nuclear Magnetic Resonance ◽  
Side Chain ◽  
Water Molecules ◽  
Carbonyl Groups ◽  
Nmr Data ◽  
Molecular Modelling Studies ◽  
Modelling Studies ◽  
Lactam Carbonyl ◽  
Self Association ◽  
Chain Conformations

Abstract The cryoscopic measurements show that title compounds are strongly associated in CHCl3 solutions. The association of the 20 R epimer is distinctly less pronounced than that of the 20 S epipmer. Self-association of the 20 S epimer leads to the formation of very large com­plexes. The 20 R epimer forms associates via water molecules. The dissimilarity may be ex­plained in terms of different accessibility of the lactam carbonyl groups in the two epimers for the association. It is proposed that the association process is controlled by the configura­tion at the carbon atom C(20) and conformation around the C(20)-C(22) bond. Populations of side chain conformations of both epimers were determined by means of proton nuclear magnetic resonance. It was found for the 20 R epimer that the t and the -g rotamers are almost equally populated, and the rotamer +g is excluded. For the 20 S epimer the +g rotamer predominates over the t one, and the -g rotamer is excluded. The NMR data are fully consistent with the results of the molecular modelling studies.

Neutral 4-phenyl-1-[phenyl(pyridin-2-yl)methylidene]semicarbazide and its salt forms with inorganic anions

2019 ◽  
Vol 75 (1) ◽  
pp. 1-7
Author(s):  
Vinicius Oliveira Araujo ◽  
Bárbara Tirloni ◽  
Lívia Streit ◽  
Vânia Denise Schwade
Keyword(s):  
Solid State ◽  
Spectroscopic Characterization ◽  
Water Molecules ◽  
Keto Form ◽  
Chloride Dihydrate ◽  
Ir And Nmr Spectroscopy ◽  
Tautomeric Forms ◽  
Counter Ions ◽  
Salt Forms ◽  
Good Agreement

Semicarbazones can exist in two tautomeric forms. In the solid state, they are found in the keto form. This work presents the synthesis, structures and spectroscopic characterization (IR and NMR spectroscopy) of four such compounds, namely the neutral molecule 4-phenyl-1-[phenyl(pyridin-2-yl)methylidene]semicarbazide, C19H16N4O, (I), abbreviated as HBzPyS, and three different hydrated salts, namely the chloride dihydrate, C19H17N4O+·Cl−·2H2O, (II), the nitrate dihydrate, C19H17N4O+·NO3 −·2H2O, (III), and the thiocyanate 2.5-hydrate, C19H17N4O+·SCN−·2.5H2O, (IV), of 2-[phenyl({[(phenylcarbamoyl)amino]imino})methyl]pyridinium, abbreviated as [H2BzPyS]+·X −·nH2O, with X = Cl− and n = 2 for (II), X = NO3 − and n = 2 for (III), and X = SCN− and n = 2.5 for (IV), showing the influence of the anionic form in the intermolecular interactions. Water molecules and counter-ions (chloride or nitrate) are involved in the formation of a two-dimensional arrangement by the establishment of hydrogen bonds with the N—H groups of the cation, stabilizing the E isomers in the solid state. The neutral HBzPyS molecule crystallized as the E isomer due to the existence of weak π–π interactions between pairs of molecules. The calculated IR spectrum of the hydrated [H2BzPyS]+ cation is in good agreement with the experimental results.

A simple procedure using trinitrobenzenesulphonic acid for monitoring proteolysis in cheese

1988 ◽  
Vol 55 (4) ◽  
pp. 585-596 ◽  
Author(s):  
Anna Polychroniadou
Keyword(s):  
Simple Procedure ◽  
Water Soluble ◽  
Acid Solutions ◽  
Amino Groups ◽  
Total N ◽  
Cheese Ripening ◽  
Amino Acid Solutions ◽  
Hydrolysis Of ◽  
Good Agreement

SummaryA simple, rapid and sensitive spectrophotometric assay was developed and evaluated for monitoring proteolysis during cheese ripening, based on the fact that α-amino groups released by hydrolysis of cheese proteins react with trinitrobenzenesulphonic acid to form products that absorb strongly at 420 nm. A linear relationship was shown to exist between A420 and concentration of free α amino groups up to 0·5 HIM (r = 0·999, 38 df, P < 0·001). Repeatability of the method was satisfactory. The coefficient of variance was 0·53% for amino acid solutions and 1·19% for cheese extracts. Average recovery of glycine added to the cheese was 104 ± 2·9%. A comparison of the above method with that of determination of water-soluble N to total N ratio showed that there was good agreement between these two methods of assessment of proteolysis in cheese (r = 0·857, 32 df, P < 0·001). Mainly Feta and Teleme cheese were examined, but a similar correlation was obtained with hard Greek cheeses. Analytical conditions of the procedure are discussed.

scholarly journals Water soluble metal-polymeric complexes of gallium and triple co-polymer of N-vinylpyrrolidone with N-vinylformamide and N-vinylminodiacetic acid

2019 ◽  
Vol 485 (3) ◽  
pp. 306-310
Author(s):  
N. I. Gorshkov ◽  
A. Yu. Murko ◽  
I. I. Gavrilova ◽  
I. I. Malakhova ◽  
V. D. Krasikov ◽  
...  
Keyword(s):  
Molecular Weight ◽  
1H Nmr ◽  
Metal Ion ◽  
Water Soluble ◽  
Polymer Complex ◽  
Nmr Data ◽  
Exclusion Chromatography ◽  
Polymeric Complexes ◽  
Metal Polymer

A terpolymer with a molecular weight of 45 kDa containing 7 mol.% of vinylamine units, 80 mol.% of vinylpyrrolidone, and 3 mol.% of vinyliminodiacetic acid units has been synthesized. Its complexation with Ga3+ ion has been studied by HPLC. The resulting metal–polymer complex has been characterized by exclusion chromatography and spectral (IR, 1H NMR) data. The complex has a monomolecular structure where the metal ion acts as an anchor fragment between vinyliminodiacetic acid units and is stable in the reaction of interligand exchange with histidine.

scholarly journals Molecular Dynamics Modellization and Simulation of Water Diffusion through Plant Cutin

1999 ◽  
Vol 54 (11) ◽  
pp. 896-902 ◽  
Author(s):  
Antonio Matas ◽  
Antonio Heredia
Keyword(s):  
Experimental Data ◽  
Molecular Dynamics ◽  
Structural Information ◽  
Md Simulations ◽  
Water Molecules ◽  
Plant Cuticle ◽  
X Ray Diffraction ◽  
Cross Link ◽  
X Ray ◽  
Good Agreement

Abstract A theoretical molecular modelling study has been conducted for cutin, the biopolyester that forms the main structural component of the plant cuticle. Molecular dynamics (MD) simulations, extended over several ten picoseconds, suggests that cutin is a moderately flexible netting with motional constraints mainly located at the cross-link sites of functional ester groups. This study also gives structural information essentially in accordance with previously reported experimental data, obtained from X -ray diffraction and nuclear magnetic resonance experiments. MD calculations were also performed to simulate the diffusion of water mole­cules through the cutin biopolymer. The theoretical analysis gives evidence that water perme­ation proceedes by a “hopping mechanism”. Coefficients for the diffusion of the water molecules in cutin were obtained from their mean-square displacements yielding values in good agreement with experimental data.

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