Thermodynamic and spectroscopic properties of 2-pyrrolidinones. 3. NMR spectroscopic studies on 2-pyrrolidinone in different solvents

1989 ◽  
Vol 2 (7) ◽  
pp. 565-572 ◽  
Author(s):  
P. Ruostesuo ◽  
P. Pirilä-Honkanen ◽  
L. Heikkinen
Keyword(s):  
Spectroscopic Properties ◽  
Spectroscopic Studies

Optical Spectroscopic Studies of a Soluble Fluorene-Based Conjugated Polymer: A Hydrostatic Pressure and Temperature Study

2001 ◽  
Vol 708 ◽  
Author(s):  
S. Guha ◽  
J.D. Rice ◽  
C. M. Martin ◽  
W. Graupner ◽  
M. Chandrasekhar ◽  
...  
Keyword(s):  
Hydrostatic Pressure ◽  
Conjugated Polymer ◽  
Spectroscopic Properties ◽  
Spectroscopic Studies ◽  
Phonon Interaction ◽  
Optical Studies ◽  
Strong Electron ◽  
Conjugated Molecules ◽  
Electron Phonon Interaction ◽  
Backbone Conformation

ABSTRACTSpectroscopic properties of conjugated molecules/polymers have varying degrees of sensitivity to backbone conformation. Optical studies are presented as a function of temperature and hydrostatic pressure, using photoluminescence and Raman scattering from two polymers with distinct differences in their backbone conformation, namely, polyfluorene (PF) and ladder type poly(para-phenylene)(m-LPPP). In contrast to the photoluminescence (PL) vibronics in mLPPP, the 0-0 PL vibronic peak in PF shows a red-shift with increasing temperatures. Pressure studies reveal that the PL spectrum of PF red-shifts and broadens with increasing pressures. The phonon lines in PF show an antiresonance effect at higher pressures indicating a strong electron-phonon interaction.

Structural and spectroscopic studies of transition metal nitrite complexes. VI. Crystal structures and spectra of Hexakis(imidazole)nickel(II) dinitrate, trans-Tetrakis(2-methylimidazole)dinitritonickel(II) and cis-Tetrakis(2-methylimidazole)-(nitrito-O,O')nickel(II) nitrate-methanol (2/1)

1981 ◽  
Vol 34 (10) ◽  
pp. 2113 ◽  
Author(s):  
AJ Finney ◽  
MA Hitchman ◽  
CL Raston ◽  
GL Rowbottom ◽  
AH White
Keyword(s):  
Crystal Structures ◽  
Symmetry Axis ◽  
Spectroscopic Properties ◽  
Spectroscopic Studies ◽  
Ligand Field ◽  
Coordination Geometry ◽  
Distorted Octahedral ◽  
Relative Field ◽  
Ligand Coordination ◽  
Fourfold Symmetry

The crystal structures and spectroscopic properties of the complexes cis-tetrakis(2-methy1imidazole)-(nitrito-O,O')nickel(II) nitrate-methanol (2/1) and trans-tetrakis(2-methylimidazole)dinitritonickel(II) are reported. The nitrite group in the former compound chelates, giving a distorted octahedral ligand coordination geometry. The ligand stereochemistry in the second complex is also a distorted octahedron, with both anions coordinating as trans nitrito groups though with significantly different Ni-O bond lengths and the nickel(II) ion being raised out of the plane of the four imidazole ligand nitrogen atoms towards the closer nitrite group. The Ni-O bond directions also deviate substantially from the fourfold symmetry axis in this latter complex. These distortions apparently occur in order to minimize ligand-ligand repulsions, particularly those associated with the amine methyl substituents. The electronic spectra of both complexes show significant band splittings due to the departure of the ligand field from regular octahedral symmetry and these are discussed in terms of the relative field strengths of the imidazole and nitrito ligands. The structure of hexakis(imidazole)nickel(II) nitrate (redetermination) is also reported.

Electrical and Raman Spectroscopic Studies on Aurivillius Layered-Pervoskite Ceramics

2019 ◽  
Vol 1154 ◽  
pp. 80-90
Author(s):  
Mohammed Abdul Basheer ◽  
Vagmare Gangadhar ◽  
Guduru Prasad ◽  
Gobburu Subramanya Kumar ◽  
Nandi Venkata Prasad
Keyword(s):  
Rare Earth ◽  
Complex Impedance ◽  
Spectroscopic Properties ◽  
Spectroscopic Studies ◽  
Rare Earth Ions ◽  
X Ray Diffraction ◽  
Raman Spectroscopic ◽  
Solid State Route ◽  
A Site ◽  
Rare Earth La

Double rare-earth (La; Sm/Gd) substituted Aurivillius family of Bismuth Layered Structured Ferroelectrics (BLSF) namely Bi2.6Sm0.2La0.2TiNbO9 (BSLT; sample-A), Bi2.6Gd0.2La0.2TiNbO9 (BGLT; sample-B), single phase ceramics were prepared by solid state route. In addition, intergrowth (x BSLT - (1-x) BGLT, where x=0.49; sample-C) and solid solution (BSLT­x - BGLTy; where x + y=0.4; sample-D) materials were prepared. Dielectric, ferroelectric and Raman spectroscopic properties were studied on the said above materials. The X-ray diffraction analysis and Raman spectra revealed well-formation of stable structure. Though, the sample-C and sample-D have lower coercive field, compared to the sample-A and sample-B, but they exhibited sharp hysterisis loop. Therefore the instrinsic defects of sample-D inhabits more sensitivity towards the ferroelectric behaviour. The results were corroborated to the impedance and dielectrical data. The results were consistent with the SEM micrographs and complex impedance plots. An attempt is made to understand the effect of rare-earth ions on A-site of layered-pervoskite structure, defined as: (Bi2O2)2+(An-1BnO3n+1)2-.The term n represents number of pervoskite blocks interleaved with the bismuth oxide layers.

scholarly journals Significance of Conformation Changes During the Binding and Release of Chromium(III) from Human Serum Transferrin

2020 ◽  
Vol 4 (Supplement_2) ◽  
pp. 1798-1798
Author(s):  
Kyle Edwards ◽  
John Vincent
Keyword(s):  
Metal Binding ◽  
Spectroscopic Properties ◽  
Spectroscopic Studies ◽  
Turnover Time ◽  
Time Intervals ◽  
Paramagnetic Resonance ◽  
Funding Sources ◽  
Research Award ◽  
Conformation Changes ◽  
Multiple Conformations

Abstract Objectives Transferrin, Tf, the protein that transports iron from the blood to the tissues via endocytosis, is believed to also transport chromium(III), Cr(III). Recently, the presence of multiple conformations was suggested by spectroscopic studies. The objective of this work is confirm whether various conformers of Cr(III)2-Tf exist and their potential significance for Cr(III) transport. Methods Cr(III) was added to apoTf in a buffered solution at pH 7.4 containing 25 mM bicarbonate at 37 °C. After time intervals, ultraviolet spectra were collected, or aliquots were removed and frozen for analysis by electron paramagnetic resonance (EPR) spectroscopy, which can distinguish free Cr(III) and Cr(III) bound to the two metal binding sites of Tf. To model the acidification of the endosome that triggers release of metal ions from Tf, the Cr(III)2-Tf conformer solutions were acidified by the addition of hydrochloric acid to pH 4.5 or 5.5. At time intervals after acidification, samples were again analyzed by ultraviolet and EPR spectroscopies. Results A combination of electronic and EPR studies reveal that the addition of Cr(III) to apoTf at near neutral pH in the presence of 25 mM bicarbonate results in the rapid binding of two Cr(III) accompanied and then followed by a series of conformation changes in Cr(III)2-Tf. These multiple conformations give rise to different spectroscopic properties and upon acidification different rates of Cr(III) release. Conclusions The conformer of Cr(III)2-Tf used in most previous studies and giving rise to EPR features at g ∼ 5.1, 5.4, and 5.6 forms too slowly to be physiologically relevant; however, two previously unknown conformers of Cr(III)2-Tf, giving rise to an EPR feature at g ∼2 and at g ∼ 5.4, respectively, were identified. The latter of these conformers has a lifespan similar to the turnover time of transferrin and releases Cr(III) rapidly, suggesting it is probably the most physiologically significant conformer of Cr(III)2-Tf. Funding Sources The University of Alabama College of Arts and Sciences Research Award.

Synthesis and spectroscopic properties of 1-(acridin-9-yl)-dipyrranes and 1-(acridin-9-yl)-dipyrrins

2009 ◽  
Vol 13 (03) ◽  
pp. 390-395 ◽  
Author(s):  
Daniel T. Gryko ◽  
Roman Voloshchuk
Keyword(s):  
Nucleophilic Addition ◽  
Spectroscopic Properties ◽  
Spectroscopic Studies ◽  
New Process ◽  
Stokes Shifts ◽  
Mediated Oxidation

A new process leading to 1-(acridin-9-yl)dipyrranes has been elaborated. The titled skeleton is assembled in a convergent fashion from 5-aryl substituted dipyrranes and acridine via a nucleophilic addition, followed by the oxidation of adducts, which are formed in situ. These products were transformed into respective 1-(acridin-9-yl)dipyrrins via 2,3-dichloro-4,5-dicyano-1,4-benzoquinone mediated oxidation. Spectroscopic studies were conducted which revealed large Stokes shifts in 1-(acridin-9-yl)dipyrranes and led to the conclusion that there is a significant conjugation between both moieties in molecules of 1-(acridin-9-yl)dipyrrins.

Nucleoside analogs involving modifications in the carbohydrate ring: nuclear magnetic resonance spectroscopic studies

1985 ◽  
Vol 63 (8) ◽  
pp. 2162-2168 ◽  
Author(s):  
Walter A. Szarek ◽  
B. Mario Pinto ◽  
Masaharu Iwakawa
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Nmr Spectroscopy ◽  
Magnetic Resonance ◽  
Nucleoside Analogs ◽  
Spectroscopic Properties ◽  
Spectroscopic Studies ◽  
Nucleoside Analog ◽  
H Nmr ◽  
Acyclic Nucleoside ◽  
C Nmr

The concomitant use of 1H nmr and 13C nmr spectroscopy as a probe of structure, stereochemistry, and conformation of several nucleoside analogs derived from 1-oxa-4-thiacyclohexane is described. The 1H nmr spectroscopic properties of an acyclic nucleoside analog derived from uridine are also described.

A fluorescent “turn on” chemosensor based on Bodipy–anthraquinone for Al(iii) ions: synthesis and complexation/spectroscopic studies

RSC Advances ◽  
2015 ◽  
Vol 5 (51) ◽  
pp. 41025-41032 ◽  
Author(s):  
Ahmed Nuri Kursunlu
Keyword(s):  
Triazole Ring ◽  
Spectroscopic Properties ◽  
Spectroscopic Studies ◽  
Turn On

A fluorescent “turn on” Al(iii) chemosensor based-on bodipy–anthraquinone with two triazole ring was prepared and studied for its complexation and spectroscopic properties.

Structural and spectroscopic studies of a nanostructured silicon–perovskite interface

Nanoscale ◽  
2020 ◽  
Vol 12 (7) ◽  
pp. 4498-4505 ◽  
Author(s):  
Roberto Gonzalez-Rodriguez ◽  
Viviana C. P. Costa ◽  
Géraud Delport ◽  
Kyle Frohna ◽  
Robert L. Z. Hoye ◽  
...  
Keyword(s):  
Spectroscopic Properties ◽  
Spectroscopic Studies ◽  
Silicon Nanotubes ◽  
Nanostructured Silicon ◽  
Inner Diameter

This work investigates the formation of APbBr3 structures (A = CH3NH3+ (MA), Cs+) in silicon and oxidized silicon nanotubes (SiNTs) with varying inner diameter, as well as the role of the interface in perovskite spectroscopic properties.

SPECTROSCOPIC STUDIES OF EXCHANGE INTERACTIONS IN POLYNUCLEAR TRANSITION METAL COMPLEXES I. [(NH3)5Cr(OH)Cr(NH3)5] Cl5,3H20.

1973 ◽  
Vol 26 (3) ◽  
pp. 505 ◽  
Author(s):  
J Ferguson ◽  
HU Gudel
Keyword(s):  
Absorption Spectrum ◽  
Single Crystals ◽  
Transition Metal Complexes ◽  
Level Scheme ◽  
Exchange Interactions ◽  
Spectroscopic Properties ◽  
Spectroscopic Studies ◽  
Luminescence Spectra ◽  
Weakly Coupled ◽  
Chloride Trihydrate

Large single crystals of ,u-hydroxo-bis[pentaamminechromium(III) chloride trihydrate have been prepared and their spectroscopic properties determined. The analysis of polarized single-crystal luminescence spectra provides an accurate ground electronic level scheme for the weakly coupled chromium ions in the dimeric cluster. The splitting is described by the isotropic Hamiltonian X = JS,.Sb-j(S,.Sb)2 with J = 31.9 cm-1 and j = 0.23 cm-1. The temperature dependence of the polarized absorption spectrum is consistent with this level scheme. The positions of the components of the singly excited (4A2-2E) state have been determined.

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