Local, solvation pressures and conformational changes in ethylenediamine aqueous solutions probed using Raman spectroscopy

2016 ◽  
Vol 18 (37) ◽  
pp. 26192-26198 ◽  
Author(s):  
Mercedes Cáceres ◽  
Alvaro Lobato ◽  
Nubia J. Mendoza ◽  
Laura J. Bonales ◽  
Valentín G. Baonza

Raman spectra of 1,2-ethylenediamine (EDA) in aqueous solutions are used to demonstrate that EDA molecules experience an anti–gauche conformational change resulting from the interactions with water.

2020 ◽  
Vol 22 (13) ◽  
pp. 7119-7125
Author(s):  
A. A. Mukadam ◽  
N. P. Aravindakshan ◽  
A. L. L. East

Misconclusions are corrected on Raman peak assignment and gauche-vs.-trans conformer ratio of ethylenediamine in liquid and aqueous phases. Peaks lost upon aqueous dilution are due to lost NH⋯N interactions. Both conformers exist in both phases.


1987 ◽  
Vol 42 (11-12) ◽  
pp. 1339-1342 ◽  
Author(s):  
H. L. Casal ◽  
U. Köhler ◽  
H. H. Mantsch ◽  
F. M. Goñi ◽  
J.L.R. Arrondo

Infrared spectra of hemoglobin (met-hemoglobin) and myoglobin were recorded in the temperature range -110 °C to 30 °C. On cooling hydroalcoholic solutions of hemoglobin, the spectra indicate a conformational change (revealed by the appearance of a band at 1665 cm-1) compatible with the appearance of distortions in its α-helical structure. In the case of myoglobin smaller effects are ob­ served. These conformational changes are entirely reversible and do not occur in frozen aqueous solutions.


1979 ◽  
Vol 34 (4) ◽  
pp. 585-590 ◽  
Author(s):  
Ralf Janda ◽  
Gert Heller

Abstract Raman spectra of solid H3BO3, Na2[B4O5(OH)4] · 8 H2O, K[B5O6(OH)4] · 2H2O and Na[B(OH)4] were recorded between 300 and 1500 cm-1 as well as of borax in aqueous solutions as a function of concentration and pH. Because of better solubility in water, the Raman spectrum of ammonium tetraborate in aqueous solution was also recorded as a function of pH. For comparisons the Raman spectra of solid (NH4)2[B4O5(OH)4] · 2 H2O, β-NH4[B5O6(OH)4] · 2 H2O, NH4[B5O6(OH)4] · 0,67 H2O and NH4[B5O6(OH)4] were considered. In solution, all lines in the Raman spectra could be assigned and the degree of depolarization measured. The assigned Raman frequencies can be used for the identification of unknown B-O-lines and therefore of unknown borate or polyborate structures.


Author(s):  
Jay Anderson ◽  
Mustafa Kansiz ◽  
Michael Lo ◽  
Curtis Marcott

Abstract Failure analysis of organics at the microscopic scale is an increasingly important requirement, with traditional analytical tools such as FTIR and Raman microscopy, having significant limitations in either spatial resolution or data quality. We introduce here a new method of obtaining Infrared microspectroscopic information, at the submicron level in reflection (far-field) mode, called Optical-Photothermal Infrared (O-PTIR) spectroscopy, that can also generate simultaneous Raman spectra, from the same spot, at the same time and with the same spatial resolution. This novel combination of these two correlative techniques can be considered to be complimentary and confirmatory, in which the IR confirms the Raman result and vice-versa, to yield more accurate and therefore more confident organic unknowns analysis.


1989 ◽  
Vol 54 (11) ◽  
pp. 3011-3024 ◽  
Author(s):  
Vlastimil Fidler ◽  
Stefan Vajda ◽  
Zuzana Limpouchová ◽  
Jiří Dvořák ◽  
Karel Procházka ◽  
...  

The methodology of polarization time-resolved fluorometry and interpretation of its results are outlined at a general level, and the measurement on and use of facilities of the Edinburgh Instruments Model 299T apparatus are discussed in detail. The dynamics of conformational changes in chains of poly(methacrylic acid) containing covalently bonded dansyl labels are studied in aqueous solutions at various pH. It is shown that at pH > 6, the shorter effective rational correlation time τr < 2 ns corresponds to the rotation of the free dansyl label about bonds by which it is attached to the polymeric chain; at pH < 4 the longer effective rational correlation time τr = 20-26 ns corresponds to the rotation of the compact spherical formation constituted by a part of the collapsed polymeric chain in which the label is fixed and whose relative molecular mass is approx. 15 000-20 000.


1994 ◽  
Vol 48 (7) ◽  
pp. 875-883 ◽  
Author(s):  
Daniel R. Lombardi ◽  
Chao Wang ◽  
Bin Sun ◽  
Augustus W. Fountain ◽  
Thomas J. Vickers ◽  
...  

Raman spectra have been measured for a number of nitrates, nitrites, sulfates, ferrocyanides, and ferricyanides, both in the solid phase and in aqueous solution. Accurate locations of peak maxima are given. Limits of detection for some of the compounds are given for solutions and for solid mixtures in NaNO3. Preliminary measurements have been made on core material recovered from the storage tanks on the Hanford site in Richland, Washington. Representative spectra are presented, showing that it is possible to observe responses of individual components from measurements made directly on untreated cores, with the use of a fiberoptic sampling probe.


2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Siti Norbaini Sabtu ◽  
S. F. Abdul Sani ◽  
L. M. Looi ◽  
S. F. Chiew ◽  
Dharini Pathmanathan ◽  
...  

AbstractThe epithelial-mesenchymal transition (EMT) is a crucial process in cancer progression and metastasis. Study of metabolic changes during the EMT process is important in seeking to understand the biochemical changes associated with cancer progression, not least in scoping for therapeutic strategies aimed at targeting EMT. Due to the potential for high sensitivity and specificity, Raman spectroscopy was used here to study the metabolic changes associated with EMT in human breast cancer tissue. For Raman spectroscopy measurements, tissue from 23 patients were collected, comprising non-lesional, EMT and non-EMT formalin-fixed and paraffin embedded breast cancer samples. Analysis was made in the fingerprint Raman spectra region (600–1800 cm−1) best associated with cancer progression biochemical changes in lipid, protein and nucleic acids. The ANOVA test followed by the Tukey’s multiple comparisons test were conducted to see if there existed differences between non-lesional, EMT and non-EMT breast tissue for Raman spectroscopy measurements. Results revealed that significant differences were evident in terms of intensity between the non-lesional and EMT samples, as well as the EMT and non-EMT samples. Multivariate analysis involving independent component analysis, Principal component analysis and non-negative least square were used to analyse the Raman spectra data. The results show significant differences between EMT and non-EMT cancers in lipid, protein, and nucleic acids. This study demonstrated the capability of Raman spectroscopy supported by multivariate analysis in analysing metabolic changes in EMT breast cancer tissue.


1982 ◽  
Vol 36 (4) ◽  
pp. 471-473 ◽  
Author(s):  
Klaus Witke

A sample cell for investigating suspensions or emulsions by Raman spectroscopy in the optically favorable 90° scattering arrangement is described. The Raman spectra of pyridine in a suspension of Aerosil 200 in carbon tetrachloride are recorded. The adsorption isotherm of pyridine is determined from the intensities of the Raman lines at 1008 and 990 cm−1. Over a long range of coverage a linear relationship exists between reciprocal concentrations of chemisorbed and dissolved molecules. The minimal surface area that is occupied by a chemisorbed molecule is determined to be approximately 0.75 nm2.


1981 ◽  
Vol 7 ◽  
Author(s):  
B.S. Elman ◽  
H. Mazurek ◽  
M.S. Dresselhaus ◽  
G. Dresselhaus

ABSTRACTRaman spectroscopy is used in a variety of ways to monitor different aspects of the lattice damage caused by ion implantation into graphite. Particular attention is given to the use of Raman spectroscopy to monitor the restoration of lattice order by the annealing process, which depends critically on the annealing temperature and on the extent of the original lattice damage. At low fluences the highly disordered region is localized in the implanted region and relatively low annealing temperatures are required, compared with the implantation at high fluences where the highly disordered region extends all the way to the surface. At high fluences, annealing temperatures comparable to those required for the graphitization of carbons are necessary to fully restore lattice order.


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