Preparation and UCST-Type Phase Behaviours of Poly(γ-4-methylbenzyl-L-glutamate) Pyridinium Tetrafluoroborate Conjugates in Methanol or Water

2017 ◽  
Vol 70 (3) ◽  
pp. 245 ◽  
Author(s):  
Sheng Liu ◽  
Chenglong Ge ◽  
Ying Ling ◽  
Haoyu Tang
Keyword(s):  
1H Nmr ◽  
Variable Temperature ◽  
Molecular Structures ◽  
Phase Behaviour ◽  
Solution Phase ◽  
Thermally Induced ◽  
Ion Exchange Reaction ◽  
Type Phase ◽  
Uv Visible ◽  
Hydrophilicity And Hydrophobicity

Polymers with ionic liquid (IL) moieties can undergo thermally induced solution phase transitions by adjusting the balance of hydrophilicity and hydrophobicity between the cations and anions of the IL moieties, thus making them attractive candidates towards various applications such as separation, sensing, and biomedicine. In the present study, a series of poly(γ-4-methylbenzyl-l-glutamate) pyridinium tetrafluoroborate conjugates (P1–P4) containing various pyridinium moieties (i.e. pyridinium, 2-methylpyridinium, 3-methylpyridinium, and 4-methylpyridinium) were prepared by nucleophilic substitution between poly(γ-4-chloromethylbenzyl-l-glutamate) and pyridine or methylpyridines with different substituent positions, followed by ion-exchange reaction in the presence of NaBF4. 1H NMR spectroscopy and Fourier transform infrared spectroscopy analyses confirmed the molecular structures of P1–P4. 1H NMR analysis additionally revealed that P1–P4 showed high grafting efficiency in the range of 93–97 %. P1, P3, and P4 exhibited reversible UCST-type phase behaviours in both methanol and water, whereas P2 showed a reversible UCST-type phase behaviour in water only. Variable-temperature UV-visible spectroscopy was used to characterize the solution phase behaviours and UCST-type phase transition temperature (Tpt) values of P1–P4, which were in the range of 24.9–37.2°C in methanol (3 mg mL–1) and 40.9–55.7°C in water (10 mg mL–1). Tpt decreased significantly with decreasing polymer concentrations.

scholarly journals Synthesis and Spectroscopic Properties of Low-Symmetry Tribenzoporphyrazines with Annulated 6H-1,4-Diazepine Ring

2008 ◽  
Vol 61 (4) ◽  
pp. 262 ◽  
Author(s):  
Maria Pia Donzello ◽  
Claudio Ercolani ◽  
Luisa Mannina ◽  
Elisa Viola ◽  
Alëna Bubnova ◽  
...  
Keyword(s):  
1H Nmr ◽  
Variable Temperature ◽  
Sodium Ethoxide ◽  
Spectroscopic Properties ◽  
Free Base ◽  
Free Energy Of Activation ◽  
Aquo Complex ◽  
Visible Spectra ◽  
Uv Visible ◽  
Low Symmetry

Template co-condensation of 2,3-dicyano-5,7-diphenyl-6H-1,4-diazepine 1 with 10-fold molar excess of phthalodinitrile 2 in the presence of MgII propoxide or butoxide in the corresponding alcohol leads to a mixture of MgII-diazepinoporphyrazines 3–6 from which the low symmetry 3:1 species 3, which contains three annulated benzene and one 1,4-diazepine rings, is separated by column chromatography as the aquo complex, [2,4-diphenyltribenzo[b,g,l][1,4]diazepino[2,3-q]porphyrazinato(aquo)magnesium(ii)], [Bz3DzPzMg(H2O)]. The complex 3 can be demetalated in acetic or trifluoroacetic acids under mild conditions with formation of the corresponding free-base [Bz3DzPzH2] 3a. This latter is also formed by co-cyclotetramerization of the same precursors 1 and 2 in the presence of sodium ethoxide in ethanol or lithium butoxide in butanol followed by demetalation of the intermediate disodium or dilithium salts in acid medium. The constitution and structure of the obtained compounds were established on the basis of elemental analysis, mass spectrometry, and 1H NMR spectra. The variable temperature 1H NMR measurements provide evidence that in porphyrazines 3 and 3a the 1,4-diazepine ring exists predominantly in the 6H-form over a wide temperature range. The free energy of activation for the inversion of the 1,4-diazepine ring determined for 3 is 45.6 ± 1.7 kJ mol–1. Solution UV-visible spectra measurements in acidic media (CH2Cl2/CF3COOH) provide evidence that the MgII complex 3 is easily protonated on the meso-N atom of the porphyrazine macrocycle followed by slow demetallation with formation of the free base 3a in its neutral form or as a species protonated on the diazepine ring.

Swollen micelles and alcohol–surfactant co-adsorption: structures and mechanisms from liquid- and solid-state 1H–1H NMR spectroscopy

2017 ◽  
Vol 19 (11) ◽  
pp. 7708-7713 ◽  
Author(s):  
Christian Totland ◽  
Anne Marit Blokhus
Keyword(s):  
Solid State ◽  
Nmr Spectroscopy ◽  
1H Nmr ◽  
1H Nmr Spectroscopy ◽  
Co Adsorption ◽  
Phase Behaviour ◽  
Liquid Interfaces ◽  
Adsorption Behaviour ◽  
Mixtures Of Surfactants ◽  
Solid Liquid

Mixtures of surfactants and medium-chained alcohols display an anomalous phase behaviour, with the formation of swollen micelles in mid-range surfactant concentrations. Such alcohols also affect the aggregation and adsorption behaviour of surfactants at solid–liquid interfaces.

ChemInform Abstract: Comparison of Variable-Temperature 1H NMR Spectra of Five-Coordinate High-Spin (S = 5/2) Iron(III) Porphyrins and Chlorins

ChemInform ◽  
1988 ◽  
Vol 19 (36) ◽  
Author(s):  
M. J. PAWLIK ◽  
P. K. MILLER ◽  
E. P. JUN. SULLIVAN ◽  
M. A. LEVSTIK ◽  
D. A. ALMOND ◽  
...  
Keyword(s):  
1H Nmr ◽  
High Spin ◽  
Nmr Spectra ◽  
Variable Temperature ◽  
1H Nmr Spectra

Study on the Inclusion Behavior of Cucurbit [n] uril with Phenylalanine

2011 ◽  
Vol 197-198 ◽  
pp. 1153-1156
Author(s):  
Ning Chen ◽  
Ya Bin Li
Keyword(s):  
1H Nmr ◽  
Interaction Mechanism ◽  
Acetate Buffer Solution ◽  
Molar Ratio ◽  
High Concentration ◽  
Buffer Solution ◽  
Visible Absorption ◽  
Nmr Spectrum ◽  
Application Range ◽  
Uv Visible

The characteristics of host-guest complexes between cucurbit[n]uril (CB [n]) and phenylalanine were investigated by UV-visible absorption spectroscopy in acetate buffer solution at room temperature. It was found that the UV-visible absorption increased steadily with constantly dropping the high concentration of cucurbit[6]uril (CB [6]) and cucurbit[8]uril (CB [8]) in the phenylalanine solution which indicates that there are some interaction betweenCB [n] and phenylalanine.Then CB [6] and phenylalanine at molar ratio of 1:1 to weigh while CB [8] and phenylalanine at molar ratio of 1:2, respectively, are both demonstrated by 1H NMR spectra. 1H NMR spectrum of complexes was obtained, indicating an enthalpic driving force for host-guest complexes. The possible interaction mechanism and inclusion mode were also discussed. This work may extend the application range of CB [n] in supramolecular and pharmaceutical analysis.

scholarly journals ISOLATION OF 2-CHLOROBENZIMIDAZOLE FROM MELIA DUBIA LEAF EXTRACT AND ITS STRUCTURAL CHARACTERISATION

2017 ◽  
Vol 9 (10) ◽  
pp. 67 ◽  
Author(s):  
G. Dayana Jeyaleela ◽  
S. Irudaya Monisha ◽  
J. Rosaline Vimala ◽  
A. Anitha Immaculate
Keyword(s):  
Mass Spectrometry ◽  
1H Nmr ◽  
Research Work ◽  
Proton Nuclear Magnetic Resonance ◽  
Resonance Spectroscopy ◽  
Ft Ir ◽  
Uv Visible ◽  
Isolated Compound ◽  
Promising Source

Objective: Natural products from medicinal plants, either as isolated compounds or as standardized plant extracts exhibit promising source of medicinal activity against various diseases. The aim of the present work was to make an attempt of isolation of bioactive principle and characterization of the isolated compound, from the medicinal plant Melia dubaiMethods: The extraction was done by a cold percolation method and the compound was separated and isolated by chromatography technique such as a thin layer chromatography (TLC), column chromatography and high-performance liquid chromatography (HPLC). The isolated compound was crystallized and the structural characterization of the isolated compound was made using UV-Visible, FT-IR, 1H-NMR, GC-MS and MS techniques which confirmed the structure of the isolated compound.Results: The separated and isolated compound was characterized by both physical and spectral methods like Ultraviolet-Visible spectroscopy (UV-Visible), Fourier transform infrared spectroscopy (FT-IR), Proton Nuclear Magnetic Resonance Spectroscopy (1H-NMR), Gas chromatography-mass spectrometry (GC-MS), and Mass spectrometry(MS). Based on the studies, organizational characteristics of one bioactive principle were deciphered. The results revealed that the isolated species is 2-chlorobenzimidazole and it agreed well with the reported value and spectra for 2-chlorobenzimidazole.Conclusion: The above results obtained in this research work clearly indicated the promising occurrence of 2-chlorobenzimidazole in Media dubia plant leaves. The future scope of these studies may guide us to view the biological activity of the isolated compound.

A variable temperature 1H NMR and DFT study of procyanidin B2 conformational interchange

2018 ◽  
Vol 29 (5) ◽  
pp. 1551-1564 ◽  
Author(s):  
S. J. O’Kennedy ◽  
A. de Villiers ◽  
D. J. Brand ◽  
W. J. Gerber
Keyword(s):  
1H Nmr ◽  
Variable Temperature ◽  
Dft Study

scholarly journals Variable temperature 1H NMR studies on Grubbs catalysts

2008 ◽  
Vol 693 (7) ◽  
pp. 1252-1260 ◽  
Author(s):  
Margaret M. Gallagher ◽  
A. Denise Rooney ◽  
John J. Rooney
Keyword(s):  
1H Nmr ◽  
Variable Temperature ◽  
Nmr Studies ◽  
Grubbs Catalysts
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