scholarly journals Synthesis and NMR studies of malonyl-linked glycoconjugates of N-(2-aminoethyl)glycine. Building blocks for the construction of combinatorial glycopeptide libraries

2016 ◽  
Vol 12 ◽  
pp. 1939-1948 ◽  
Author(s):  
Markus Nörrlinger ◽  
Sven Hafner ◽  
Thomas Ziegler
Keyword(s):  
Nmr Spectroscopy ◽  
Formic Acid ◽  
Building Blocks ◽  
Propanoic Acid ◽  
Temperature Dependent ◽  
Nmr Studies ◽  
H Nmr ◽  
Fmoc Group ◽  
Aqueous Formic Acid ◽  
Coalescence Temperature

Four glycoconjugate building blocks for the construction of combinatorial PNA like glycopeptide libraries were prepared in 75–79% yield by condensing tert-butyl N-[2-(N-9-fluorenylmethoxycarbonylamino)ethyl]glycinate (AEG) 5 with 3-oxo-3-(2,3,4,6-tetra-O-acetyl-β-D-glucopyranosylamino)- (6a), 3-oxo-3-(β-D-galactopyranosylamino)- (6b), 3-oxo-3-(2-acetamido-2-deoxy-3,4,6-tetra-O-acetyl-β-D-glucopyranosylamino)- (6c) and 3-oxo-3-(2-acetamido-2-deoxy-3,4,6-tetra-O-acetyl-β-D-galactopyranosylamino)propanoic acid (6d), respectively. The resulting AEG glycoconjugates 1a–d were converted into the corresponding free acids 2a–d in 97–98% yield by treatment with aqueous formic acid. The Fmoc group of compound 1c was removed and the intermediate amine 9 was condensed with 2a to afford the corresponding glycosylated AEG dipeptide 4 in 58% yield. All glycoconjugate building blocks showed the presence of cis and trans rotamers. Compounds 1a, 1b and 4 were subjected to temperature dependent 1H NMR spectroscopy in order to determine the coalescence temperature which resulted in calculated rotation barriers of 17.9–18.3 kcal/mol for the rotamers.

scholarly journals Water-soluble β-aminobisulfonate building blocks for pH and Cu2+ indicators

RSC Advances ◽  
2016 ◽  
Vol 6 (88) ◽  
pp. 84712-84721 ◽  
Author(s):  
Maria A. Cardona ◽  
Marina Kveder ◽  
Ulrich Baisch ◽  
Michael R. Probert ◽  
David C. Magri
Keyword(s):  
Nmr Spectroscopy ◽  
Building Blocks ◽  
Water Soluble ◽  
Visible Absorption ◽  
H Nmr ◽  
Uv Visible

Two phenyl β-aminobisulfonate ligands characterised by UV-visible absorption, EPR and 1H NMR spectroscopy exhibit evidence for binding with Cu2+ in water and methanol.

Die intramolekulare Beweglichkeit von Alkinen in Wolframkomplexen des Typs C5H5W(CO)(L)R (L = Alkin; R = CH3, C6H5) / The Intramolecular Mobility of Alkynes in Tungsten Compounds of the Type C5H5W(CO)(L)R (L = Alkyne; R = CH3, C6H5)

1977 ◽  
Vol 32 (2) ◽  
pp. 144-147 ◽  
Author(s):  
H. G. Alt ◽  
W. Stadler
Keyword(s):  
Nmr Spectroscopy ◽  
Temperature Dependent ◽  
H Nmr ◽  
Intramolecular Mobility ◽  
Type C

Complexes of the type C5H5W(CO)(L)R (L = alkyne; R = CH3, C6H5) are obtained by irradiation of a solution containing both C5H5W(CO)3R and L. The intramolecular mobility of the π-bonded acetylene in the 16-electron complexes C5H5W(CO)(L)R can be demonstrated by temperature-dependent 1H NMR spectroscopy.

A pentaammineruthenium(III) dimer with the novel bridging ligand 4,4′-dicyanamidobiphenyl dianion

1996 ◽  
Vol 74 (11) ◽  
pp. 2201-2208 ◽  
Author(s):  
Christopher A. White ◽  
Corinne Bensimon ◽  
Robert J. Crutchley ◽  
Manuel A.S. Aquino ◽  
J.E. Greedan
Keyword(s):  
Cyclic Voltammetry ◽  
Nmr Spectroscopy ◽  
Mixed Valence ◽  
The Novel ◽  
Temperature Dependent ◽  
Monoclinic Crystal ◽  
H Nmr ◽  
Weakly Coupled ◽  
Anti Conformation ◽  
Mixed Valence Complex

The novel ligand 4,4′-dicyanamidobiphenyl dianion (bp2−) has been synthesized and characterized by 13C NMR spectroscopy, cyclic voltammetry, and crystallography. The crystal structure of [Ph4As]2[bp]•H2O showed that bp2− is approximately planar with a dihedral angle of 8.2° between phenyl ring planes and the cyanamide groups in an anti conformation. The water of crystallization is asymmetrically hydrogen bonded between cyanamide groups of adjacent bp2− ions. The crystal data for C62H48N4As2 + H2O are monoclinic crystal system and space group P21/c with a = 12.998(5) Å, b = 13.465(4) Å, c = 28.703(13) Å, β = 98.94(3)°, V = 4963(3) Å3 and Z = 4. The structure was refined by using 4555 reflections with I > 2.5σ(I) to an R factor of 0.058. The complex, [{(NH3)5Ru)2(μ-bp)][X]4, where X = tosylate or PF6− ions, was also synthesized and characterized by 1H NMR spectroscopy, cyclic voltammetry, spectroelectrochemistry, and temperature-dependent magnetic susceptibility measurements. From cyclic voltammetry measurements, the comproportionation constants to form the mixed-valence complex [{(NH3)5Ru)2(μ-bp)]3+ were estimated to be 4.1, 16, and 22 in water, acetonitrile, and nitromethane, respectively. The trend and magnitude of Kc suggests solvent valence trapping of a weakly coupled Class II ion. The MMCT band of the mixed-valence complex had to be deconvoluted from the low-energy LMCT band and had the following properties in acetonitrile, νmax = 8400 cm−1, εmax = 3300 M−1 cm−1, and Δν1/2 = 3300 cm−1. The weak superexchange mediating properties of bp2− compared to 1,4-dicyanamidobenzene dianion were suggested to arise from the larger barrier to the formation of the radical anion bp−. Key words: cyanamido, mixed valence, superexchange, ruthenium.

EM studies of long-lived fiber gels complemented by solid state 2H-NMR spectroscopy

1990 ◽  
Vol 48 (4) ◽  
pp. 852-853
Author(s):  
Sönke Svenson
Keyword(s):  
Solid State ◽  
Nmr Spectroscopy ◽  
Sodium Dodecylsulfate ◽  
Preparative Method ◽  
Temperature Dependent ◽  
H Nmr ◽  
Sds Micelles ◽  
Dispersed Particles ◽  
Aqueous Gels ◽  
High Concentrations

Aqueous gels (1%) consisting of the amphiphilic N-octyl-D- gluconamide (D-Glu-8) usually crystallize within a few hours.They remain stable for more than five months if 0.4% of sodium dodecylsulfate (SDS) is added. It was shown by electron microscopy that the gels are formed by helical fibers of at least bimolecular thickness (4 nm) and of several micrometers length. Randomly dispersed particles with a mean diameter of 5 nm, which are assumed as micelles, were also observed on micrographs (Fig.1).To provide evidence for this assumption and to rule out the possibility of artefacts introduced by the preparative method, we applied an additional technique, namely solid state 2H-NMR spectroscopy. The spectra point out the temperature dependent equilibrium between “solid” fibers and micelles, as represented by the Pake powder spectrum and the isotropic central singlet (Fig.2). The micellar part of the equilibrium is strongly enhanced in the presence of detergents such as SDS. High concentrations of SDS micelles extend the gel’s lifetime, presumably because these micelles dissolve the crystallization nuclei of D-Glu-8 and thus, prevent further crystal growth.

119Sn, 13C and 1H NMR studies of aryloxy- and arylthio(1-butyl)stannanes

1989 ◽  
Vol 54 (9) ◽  
pp. 2386-2398 ◽  
Author(s):  
Antonín Lyčka ◽  
Jaroslav Holeček ◽  
Karel Handlíř
Keyword(s):  
Nmr Spectroscopy ◽  
Organic Compounds ◽  
1H Nmr ◽  
Organotin Compounds ◽  
Nmr Studies ◽  
Spectral Parameters ◽  
H Nmr ◽  
Mutual Comparison ◽  
Aromatic Systems

Two series of compounds have been prepared and studied by means of 119Sn, 13C, and 1H NMR spectroscopy, viz. aryloxy- and N-heteroaryloxytris(1-butyl)stannanes and their thio analogues Bu3SnER, and diaryloxy- and di(N-heteroaryloxy)bis(1-butyl)stannanes and their thio analogues Bu2Sn(ER)2, where E means oxygen or sulfur, Bu is 1-butyl, R = phenyl, 1-naphthyl, or 8-quinolyl. On the basis of mutual comparison of NMR spectral parameters of both series of organotin compounds and their comparison with NMR spectral parameters of analogous, purely organic compounds CH3ER it is possible to discuss the consequences of the presence of tin atoms in the organotin substituents and of nitrogen heteroatoms in the aromatic systems, and the therefrom following structure of the organotin compounds studied.

scholarly journals Proton NMR Studies on the Conformation of the Pterin Cofactor Bound at the Active Site of Recombinant Human Tyrosine Hydroxylase

Pteridines ◽  
1998 ◽  
Vol 9 (1) ◽  
pp. 44-52 ◽  
Author(s):  
Aurora Martínez ◽  
Olga Vageli ◽  
Wolfgang Pfleiderer ◽  
Torgeir Flatmark
Keyword(s):  
Nmr Spectroscopy ◽  
Tyrosine Hydroxylase ◽  
Active Site ◽  
Average Distance ◽  
Bond Formation ◽  
Pyrimidine Ring ◽  
Anaerobic Conditions ◽  
Nmr Studies ◽  
H Nmr ◽  
Pterin Cofactor

SummaryThe binding of L-erythro-7,S-dihydrobiopterin (BH2) in the presence of L-Phe to recombinant human tyrosine hydroxylase was studied by 1H-NMR spectroscopy. The distances (± 1.3 A) from the active site metal were estimated to be 5 .3-6.4 A for observable protons of BH2 and 7 .0-7.9 A for L-Phe protons. Due to the lack of constraints from the pyrimidine ring in BH2 , two families of conformers were computed, with an average distance from the C4a in the pterin ring to the iron of 3.7 A (family A) and S.S A (family B). The conformers for 6-methyl-tetrahydropterin bound to the enzyme at near anaerobic conditions in the absence of L-Phe were also grouped into two families, with C4a-metal distances of 3.0-4.0 A (A) and 7.0-7.5 A (B). Based on the estimated conformation of the enzyme bound 5,6,7,S-tetrahydro- 3-methylpterin, family A of conformers was selected for both oxidized and reduced pterins. Our results indicate that the pterin does not coordinate to the iron, which seems to be involved both in the binding and activation of O2 and in the C-O bond formation in the aromatic ring of the substrate.

Enolates de β-cétoesters: conformations et stabilités des formes dissociées

1982 ◽  
Vol 60 (5) ◽  
pp. 634-642 ◽  
Author(s):  
C. Cambillau ◽  
F. Guibe
Keyword(s):  
Nmr Spectroscopy ◽  
A Priori ◽  
Experimental Results ◽  
Nmr Studies ◽  
H Nmr ◽  
Geometrical Constraints

The problem of the conformation of β-ketoester enolates has been investigated through 1H nmr studies and through conductimetrie studies. We have compared the dissociative properties of the K+ enolates of acyclic β-ketoesters which can a priori adopt any possible ZE, ZZ, EE, or EZ conformations and of hemicyclic β-ketoesters (2-carbethoxycyclopentanone, 2-acetyl γ-butyrolactone) in which geometrical constraints excluded some of them. The results lead to the conclusion that the EE conformation is more stable than either the ZZ or EZ ones. Confirmation of this point, which implies that the acyclic dissociated enolates exist in the EE conformation, is afforded by 1H nmr spectroscopy. Those experimental results have been complemented with abinitio STO-3G calculations performed on the methyl formylacetate anion and on the formylacetone anion (the diketonic analog). The method of conductimétrie titration by cryptand (2,2,2) used for the determination of the dissociation coefficient of K+ enolates in DMSO is discussed in some detail.

Cp′—X—Cp′-überbrückte μ-Cyclooctatetraen- und -trien-Zweikernkomplexe des Chroms sowie Vanadiums (Cp′ = η5-C5H4, X = CH2, SiMe2, GeMe2) / Binuclear Cp′–X–Cp′-Bridged μ-Cyclooctatetraene and -triene Complexes of Chromium as well as Vanadium (Cp′ = η5-C5H4, X = CH2, SiMe2, GeMe2)

1990 ◽  
Vol 45 (2) ◽  
pp. 221-238 ◽  
Author(s):  
Bernd Bachmann ◽  
Gerhard Baum ◽  
Jürgen Heck ◽  
Werner Massa ◽  
Bernd Ziegler
Keyword(s):  
Temperature Dependent ◽  
Nmr Studies ◽  
One Pot ◽  
X Ray ◽  
H Nmr ◽  
Metal Metal ◽  
Structure Determinations ◽  
Work Up ◽  
Conditions Of Work ◽  
By Products

Synfacial binuclear μ-Cot complexes of the general formula X(Cp′M)2— μ-Cot with Cp′—X—Cp′ as an additional bridging group (M = V, Cr; Cot = cyclooctatetraene) can be prepared by a one-pot reaction of the appropriate metal dichlorides with K2Cot and Li2[(C5H4)2X]. For M = V the vanadocenophanes {V(Cp'2X)}2 (X = SiMe2, GeMe2) are isolated as by-products. Depending on the conditions of work-up for M = Cr µ-(σ:η3:η2-cyclooctatriene) complexes can be obtained instead of the μ-Cot compounds. X-ray structure determinations of several μ-Cot species attest only a poor influence of the bridging group X on the metal metal bond. Low temperature 1H NMR spectra of the dichromium μ-Cot complexes show that the rapid Cotrotation can be frozen below T = 200 K. Temperature dependent 1H NMR studies indicate a diamagnetic-paramagnetic equilibrium for the binuclear μ-C8H10 compounds, wherein a Cr,Crmultiple bond must be assumed.

scholarly journals Synthesis and characterization of alternating poly(amide urea)s and poly(amide urethane urethane)s from ε-caprolactam, diamines, and diphenyl carbonate or ethylene carbonate

e-Polymers ◽  
2003 ◽  
Vol 3 (1) ◽  
Author(s):  
Luc Ubaghs ◽  
Bhaskar Sharma ◽  
Helmut Keul ◽  
Hartwig Höcker ◽  
Ton Loontjens ◽  
...  
Keyword(s):  
Thermal Properties ◽  
Nmr Spectroscopy ◽  
Ethylene Carbonate ◽  
Building Blocks ◽  
Diphenyl Carbonate ◽  
Scanning Calorimetry ◽  
Molecular Weights ◽  
H Nmr ◽  
End Groups

Abstract Alternating poly(amide urea)s from ε-caprolactam, diamines H2N-(CH2)x- NH2 (x = 2 - 4), and diphenyl carbonate were prepared in two steps. The microstructure of the poly(amide urea)s, as determined by means of 1H NMR spectroscopy, reveals a strictly alternating sequence of the building blocks. The molecular weights and polydispersities obtained were 7500 < Mn < 10 000 and 1.48 < Mw/Mn < 1.56, respectively. Thermal properties were determined by means of differential scanning calorimetry (DSC) (163.9°C < Tm < 197.2°C; 55.5°C < Tg (2nd heating) < 72.2°C), and thermogravimetric analysis (TGA). TGA shows a three-step decomposition at 200, 350, and 450°C, which was attributed to the cleavage of O-phenyl urethane end groups, as well as urea and amide linkages. These assignments were made by comparison with model compounds. Furthermore, alternating poly- (amide urethane urethane)s from ε-caprolactam, diamines, and ethylene carbonate were prepared in three steps. The microstructure of the poly(amide urethane urethane)s, as determined by means of 1H NMR spectroscopy, reveals imperfections. The molecular weights and polydispersities obtained were 5400 < Mn < 17 000 and 2.08 < Mw/Mn < 2.99, respectively. Thermal properties were determined by means of DSC (155.9°C < Tm < 159.0°C; 35.5°C < Tg (2nd heating) < 39.0°C) and TGA. TGA shows a complex decomposition due to the formation of ethylene carbonate by cleavage of the urethane groups (at approx. 230°C) and formation of poly(amide urea)s. The newly formed poly(amide urea)s decompose in a similar way as the poly(amide urea)s.

Photochemische Umsetzungen von η5-Indenyl-tricarbonyl-methyl-molybdän und -wolfram, C9H7M(CO)3CH3 (M = Mo, W), mit Acetylenen / Photochemical Reactions of Indenyl-tricarbonyl-methyl-molybdenum and -tungsten, C9H7M(CO)3CH3 (M = Mo, W), with Acetylenes

1977 ◽  
Vol 32 (10) ◽  
pp. 1139-1144 ◽  
Author(s):  
H. G. Alt
Keyword(s):  
Nmr Spectroscopy ◽  
Uv Irradiation ◽  
Photochemical Reactions ◽  
Temperature Dependent ◽  
H Nmr ◽  
Intramolecular Mobility ◽  
Indenyl Complexes ◽  
And Tungsten

The photoreaction of the indenyl complexes C9H7M(CO)3CH3 (M = Mo, W) with alkynes (L) in solution leads to 1:1 adducts, which are found to be metallocyclic alkenylketone compounds C9H7M(CO)2(L-COCH3). UV irradiation of C9H7W(CO)3CH3 in the presence of either acetylene or methylacetylene also gives substituted derivatives C9H7W(CO)(L)CH3 in low yields. For these compounds, the intramolecular mobility of the π-bonded alkyne ligand can be demonstrated by temperature-dependent 1H NMR spectroscopy.

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