scholarly journals The photoisomerization of cis,trans-1,2-dideuterio-1,4-diphenyl-1,3-butadiene in solution. No bicycle-pedal

2019 ◽  
Vol 18 (9) ◽  
pp. 2174-2179
Author(s):  
Jack Saltiel ◽  
Christopher E. Redwood ◽  
Ratheesh Kumar V. K.
Keyword(s):  
Nmr Spectroscopy ◽  
Room Temperature ◽  
H Nmr

cis,trans-1,2-Dideuterio-1,4-diphenyl-1,3-butadiene (ct-DPBd2) was synthesized and its cis–trans photoisomerization in cyclohexane-d12 (C6D12) at room temperature was monitored by 1H NMR spectroscopy.

Das dynamische Verhalten des 1-Methyl-1-benzothiepinium-Ringsystems/The Dynamic Behaviour of the 1-Methyl-1-benzothiepinium Ring System

1981 ◽  
Vol 36 (8) ◽  
pp. 974-977 ◽  
Author(s):  
Hans Hofmann ◽  
Franz Dickert
Keyword(s):  
Nmr Spectroscopy ◽  
Room Temperature ◽  
Dynamic Behaviour ◽  
Ring System ◽  
Membered Ring ◽  
Ring Inversion ◽  
Methyl Group ◽  
H Nmr ◽  
Pyramidal Inversion ◽  
Mutual Conversion

Abstract By 1H NMR spectroscopy the stereochemistry of the 1-methyl-1-benzothiepinium ring system was investigated both in thermodynamic and kinetic respects. It was shown that in solution a rapid mutual conversion of the boat shaped seven membered ring system with exo-respectively endo-S-methyl group occurs via a ring inversion and not by a pyramidal inversion at the sulfonium ion. At room temperature predominantly the conformation with the exo-S-methyl group is present.

Reactions of 7-azaindole with niobium and tantalum pentachlorides and coupling to the azaindolyl-azaindolium cation

1994 ◽  
Vol 72 (7) ◽  
pp. 1675-1683 ◽  
Author(s):  
Jacques Poitras ◽  
André L. Beauchamp
Keyword(s):  
Infrared Spectroscopy ◽  
Nmr Spectroscopy ◽  
Crystal Structures ◽  
Infrared Spectra ◽  
Oxidative Coupling ◽  
Room Temperature ◽  
H Nmr ◽  
Counter Ion ◽  
Distorted Octahedral ◽  
Complex Salts

The reaction of NbCl5 and TaCl5 with 7-azaindole (Haza) at room temperature in benzene or dichloromethane yielded MCl5(Haza) addition compounds. Under more severe conditions, the same compound was obtained with TaCl5. For NbCl5, some reduction to Nb(IV) was observed and NbCl5(Haza), NbCl4(Haza)2, and the (H2aza)+ ion were identified in the reaction mixture by infrared spectroscopy. Oxidative coupling of two azaindole units via N7—C6 also took place during the reaction, since the 7-(azaindol-6-yl)azaindolium cation was found as counter-ion in the crystal structures of two complex salts. In the crystals of (H2aza-aza)[NbOCl4(Haza)]•0.5CH2Cl2([Formula: see text]a = 7.255 Å, b = 12.412 Å, c = 14.277 Å, α = 89.03°, β = 85.60°, γ = 76.66°, Z = 2, R = 0.062), the anion is the roughly octahedral [NbOCl4(azaindole)]− species containing a neutral N7-coordinated azaindole trans to the Nb=O bond. The [NbOCl5]2− salt ([Formula: see text]a = 7.527 Å, b = 10.168 Å, c = 10.467 Å, α = 66.41°, β = 84.07°, γ = 85.51°, Z = 1, R = 0.037) contains the distorted octahedral [NbOCl5]2− ion disordered over two orientations. The infrared spectra suggest monomeric octahedral structures for the MCl5(Haza) and NbCl4(Haza)2 complexes. 1H NMR spectroscopy shows that NbCl5(Haza) is not dissociated in CD2Cl2.

scholarly journals Stereochemistry of Two Hydroxybiflavanonols from Garcinia cola Nuts

1987 ◽  
Vol 42 (7-8) ◽  
pp. 855-857 ◽  
Author(s):  
Johann Sonnenbichler ◽  
Ifeanyi Madubunyi ◽  
Hugo Scheer
Keyword(s):  
Nmr Spectroscopy ◽  
Absolute Configuration ◽  
Room Temperature ◽  
H Nmr ◽  
The Absolute

The absolute configuration of two hydroxybiflavanonols from Garcinia cola nuts have been determined by CD and 500 MHz 1H NMR spectroscopy. Additionally the occurrence of atrop-isomers at room temperature as the consequence of rotational hindrance in the molecules could be demonstrated.

Application of NMR Spectroscopy to the Study of Piperidine Derivatives. Part III: Molecular Dynamics Study of N-Benzyl-4-[N-Benzyloxyacetyl)-(2-Fluorophenyl)]Amino-3-Methyl Piperidine

1993 ◽  
Vol 47 (3) ◽  
pp. 357-359 ◽  
Author(s):  
A. L. Cholli ◽  
M. L. Lau
Keyword(s):  
Molecular Dynamics ◽  
Nmr Spectroscopy ◽  
High Resolution ◽  
Detailed Analysis ◽  
Room Temperature ◽  
Variable Temperature ◽  
Proton Nmr ◽  
Nmr Spectrum ◽  
H Nmr ◽  
Nmr Data

High-resolution 1H NMR has been used to study the molecular dynamics of the piperidine derivative. Detailed analysis of variable temperature NMR data allowed the identification of the origin of two sets of methyl resonance peaks with unequal intensities in the room-temperature proton NMR spectrum of the compound.

Photochemical generation and 1H NMR detection of alkyl allene oxides in solution

2005 ◽  
Vol 83 (9) ◽  
pp. 1347-1351 ◽  
Author(s):  
Leah E Breen ◽  
Norman P Schepp ◽  
C-H Edmund Tan
Keyword(s):  
Nmr Spectroscopy ◽  
Significant Influence ◽  
Alkyl Group ◽  
Room Temperature ◽  
Nucleophilic Attack ◽  
Allene Oxide ◽  
Lifetime Measurements ◽  
H Nmr ◽  
Photochemical Generation ◽  
Allene Oxides

Irradiation of substituted 5-alkyl-4,5-epoxyvalerophenones leads to the formation of alkyl allene oxides that, in some cases, are sufficiently long-lived to be detected at room temperature by 1H NMR spectroscopy. Absolute lifetime measurements show that the size of the alkyl group has a significant influence on the reactivity of the allene oxide, with tert-butyl allene oxide having a lifetime of 24 h in CD3CN at room temperature that is considerably longer than the 1.5 h lifetime of the ethyl allene oxide. The allene oxides react rapidly with water to give α-hydroxyketones. The mechanism involves nucleophilic attack to the epoxide carbon to give an enol, which can also be detected as an intermediate by 1H NMR spectroscopy.Key words: allene oxides, mechanisms, absolute reactivity, kinetics, photochemistry.

The Preparation of Some Mono-and Bis(thiolate)-2-butyne Complexes of Tungsten(II) of the Types [WI(SR)(CO)(dppm )(η2-MeC2Me)] {dppm = Ph2P(CH2)PPh2; R = Et, But, Ph or CH2Ph} and [W (SR)2(CO)(dppm)(η2-MeC2Me)]

1994 ◽  
Vol 49 (11) ◽  
pp. 1544-1548 ◽  
Author(s):  
Paul K. Baker ◽  
Kevin R. Flower
Keyword(s):  
Nmr Spectroscopy ◽  
Elemental Analysis ◽  
Good Yield ◽  
Nmr Spectra ◽  
Room Temperature ◽  
H Nmr ◽  
Thiolate Complexes ◽  
C Nmr

Equimolar quantities of [WI(CO)(NCMe)(dppm)(η2-MeC2Me)][BF4] {dppm = Ph2P(CH2)PPh2) and NaSR (R = Et. But ,Ph or CH2Ph) react in CH2Cl2 at room temperature to give the neutral thiolate complexes [WI(SR)(CO)(dppm)(η2-MeC2Me)] (1 → 4) in good yield. The complex [WI(CO)(NCMe)(dppm)(η2-MeC2Me)][BF4] also reacts with two equiv­alents of NaSR (R = Et. But, Ph or CH2Ph) in CH2Cl2 at room temperature to afford the bis(thiolate) complexes [W(SR)2(CO)(dppm)(η2-MeC2Me)] (5 → 8), in good yield. Com­plexes 1→8 have been characterized by elemental analysis (C, H and N), IR and 1H NMR spectroscopy. 13C NMR spectra of selected complexes indicate that the 2-butyne ligand is donating four electrons to the metal in both [WI(SR)(CO)(dppm)(η2-MeC2Me)] and [W(SR)2(CO)(dppm)(η2-MeC2Me)] type complexes.

Conformational study on ribonucleoside O-phosphonylmethyl derivatives by 1H NMR spectroscopy

1985 ◽  
Vol 50 (8) ◽  
pp. 1899-1905 ◽  
Author(s):  
Milena Masojídková ◽  
Jaroslav Zajíček ◽  
Miloš Buděšínský ◽  
Ivan Rosenberg ◽  
Antonín Holý
Keyword(s):  
Nmr Spectroscopy ◽  
1H Nmr ◽  
1H Nmr Spectroscopy ◽  
Conformational Study ◽  
H Nmr ◽  
Conformational Properties

Conformational properties of ribonucleoside 5'-O-phosphonylmethyl derivatives have been determined by 1H NMR spectroscopy and compared with those of natural nucleosides and 5'-nucleotides.

Monitoring the encapsulation of chlorin e6 derivatives into polymer carriers by NMR spectroscopy

2019 ◽  
Vol 23 (11n12) ◽  
pp. 1576-1586 ◽  
Author(s):  
Sara Pfister ◽  
Luca Sauser ◽  
Ilche Gjuroski ◽  
Julien Furrer ◽  
Martina Vermathen
Keyword(s):  
Relaxation Time ◽  
Nmr Spectroscopy ◽  
Core Region ◽  
Chlorin E6 ◽  
Polypropylene Glycol ◽  
Polymer Carriers ◽  
H Nmr ◽  
Line Shape Analysis ◽  
Dynamic Methods ◽  
Derivatives Of

The encapsulation of five derivatives of chlorin e6 with different hydrophobicity and aggregation properties into a series of five poloxamer-type triblock copolymer micelles (BCMs) with varying numbers of polyethylene and polypropylene glycol (PEG, PPG) units was monitored using 1H NMR spectroscopy. NMR chemical shift and line shape analysis, as well as dynamic methods including diffusion ordered spectroscopy (DOSY) and T1 and T2 relaxation time measurements of the chlorin and the polymer resonances, proved useful to assess the chlorin–BCM compatibility. The poloxamers had high capability to break up aggregates formed by chlorins up to intermediate hydrophobicity. Physically entrapped chlorins were always localized in the BCM core region. The loading capacity correlated with chlorin polarity for all poloxamers among which those with the lowest number of PPG units were most efficient. DOSY data revealed that relatively weakly aggregating chlorins partition between the aqueous bulk and micellar environment whereas more hydrophobic chlorins are well retained in the BCM core region, rendering these systems more stable. T1 and T2 relaxation time measurements indicated that motional freedom in the BCM core region contributes to encapsulation efficiency. The BCM corona dynamics were rather insensitive towards chlorin entrapment except for the poloxamers with short PEG chains. The presented data demonstrate that 1H NMR spectroscopy is a powerful complementary tool for probing the compatibility of porphyrinic compounds with polymeric carriers such as poloxamer BCMs, which is a prerequisite in the development of stable and highly efficient drug delivery systems suitable for medical applications like photodynamic therapy of tumors.

Different submicellar solubilization mechanisms revealed by 1H NMR and 2D diffusion ordered spectroscopy (DOSY)

2020 ◽  
Vol 22 (19) ◽  
pp. 11075-11085
Author(s):  
Mengjian Wu ◽  
Zhaoxia Wu ◽  
Shangwu Ding ◽  
Zhong Chen ◽  
Xiaohong Cui
Keyword(s):  
Nmr Spectroscopy ◽  
Sodium Dodecyl Sulfate ◽  
1H Nmr ◽  
Sodium Dodecyl ◽  
Butyl Methacrylate ◽  
H Nmr ◽  
Molecular Scale ◽  
Two Systems ◽  
Dodecyl Sulfate ◽  
Triton X

Different submicellar solubilization mechanisms of two systems, Triton X-100/tetradecane and sodium dodecyl sulfate (SDS)/butyl methacrylate, are revealed on the molecular scale by 1H NMR spectroscopy and 2D diffusion ordered spectroscopy (DOSY).

scholarly journals Structure and dynamics of room temperature ionic liquids with bromide anion: results from 81 Br NMR spectroscopy

2015 ◽  
Vol 53 (5) ◽  
pp. 369-378 ◽  
Author(s):  
Takatsugu Endo ◽  
Mamoru Imanari ◽  
Yuki Hidaka ◽  
Hiroko Seki ◽  
Keiko Nishikawa ◽  
...  
Keyword(s):  
Ionic Liquids ◽  
Nmr Spectroscopy ◽  
Room Temperature ◽  
Room Temperature Ionic Liquids ◽  
Bromide Anion ◽  
Structure And Dynamics
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