Two-Dimensional Correlation Spectroscopy Study of Temperature-Dependent Spectral Variations ofN-Methylacetamide in the Pure Liquid State. 1. Two-Dimensional Infrared Analysis

1996 ◽  
Vol 100 (21) ◽  
pp. 8665-8673 ◽  
Author(s):  
Isao Noda ◽  
Yongliang Liu ◽  
Yukihiro Ozaki
Keyword(s):  
Liquid State ◽  
Correlation Spectroscopy ◽  
Infrared Analysis ◽  
Pure Liquid ◽  
Two Dimensional ◽  
Spectroscopy Study ◽  
Temperature Dependent ◽  
State 1

Two-Dimensional Infrared and Near-Infrared Correlation Spectroscopy: Applications to Studies of Temperature-Dependent Spectral Variations of Self-Associated Molecules

1997 ◽  
Vol 51 (4) ◽  
pp. 526-535 ◽  
Author(s):  
Yukihiro Ozaki ◽  
Yongliang Liu ◽  
Isao Noda
Keyword(s):  
Near Infrared ◽  
Oleyl Alcohol ◽  
Correlation Spectroscopy ◽  
Intensity Change ◽  
Pure Liquid ◽  
Two Dimensional ◽  
Temperature Dependent ◽  
Thermally Induced ◽  
2D Ir ◽  
Almost All

This paper demonstrates the potential of generalized two-dimensional (2D) Fourier transform (FT) infrared (IR) and near-infrared (NIR) correlation spectroscopy in the studies of temperature-dependent spectral variations of self-associated molecules. Three examples of the 2D correlation analysis are discussed in this paper. The first two are concerned with the temperature-dependent IR and NIR spectral changes of N-methylacetamide (NMA) in the pure liquid state. The 2D IR correlation approach revealed that almost all the peaks of NMA in the 3400–1100-cm−1 region consist of two to four separate bands. For example, the amide I band contains contributions from at least four distinct bands at 1685, 1665, 1650, and 1635 cm−1. The analysis of the asynchronous 2D IR spectrum in the amide I region showed that the sequence of spectral intensity change in the ascending order of temperature was given by 1635<1650<1665<1685 cm−1. These bands at 1635, 1650, 1665, and 1685 cm−1 were assigned to the amide I modes of chain oligomers of various sizes and dimer of NMA; the longer the chain, the lower the frequency. The closeup view of 2D NIR correlation spectra of NMA obtained at narrow spectral and temperature windows enabled us to propose not only band assignments in the 6800–6050-cm−1 region but also a detailed mechanistic picture of the thermally induced dissociation of NMA for each temperature range. We also applied the generalized 2D correlation approach to the analysis of a set of FT NIR spectra of oleyl alcohol under temperature variations. The 2D NIR analysis enhanced the spectral resolution and simplified the spectra with overlapped bands. For example, it was found that a band at 7090 cm−1 arising from the first overtone of an OH stretching mode of the monomeric alcohol consists of two bands due to the rotational isomerism of the free OH group. An intriguing possibility of correlating various overtone and fundamental bands to establish unambiguous assignments was also suggested from the 2D NIR study on oleyl alcohol.

Potential of Generalised Two-Dimensional Correlation Spectroscopy in the near Infrared Region

1996 ◽  
Vol 4 (1) ◽  
pp. 85-99 ◽  
Author(s):  
Yukihiro Ozaki ◽  
Isao Noda
Keyword(s):  
Near Infrared ◽  
Infrared Region ◽  
Carbonyl Oxygen ◽  
Correlation Spectroscopy ◽  
Pure Liquid ◽  
Two Dimensional ◽  
Temperature Dependent ◽  
Thermally Induced ◽  
Correlation Spectrum ◽  
Nylon 12

This review demonstrates the potential of generalised two-dimensional (2D) correlation spectroscopy in the near infrared (NIR) region. Three examples of generalised 2D NIR correlation analysis, which are all concerned with the temperature-dependent spectral variations of self-associated molecules, are discussed in this paper. The first example presents the 2D correlation approach to the analysis of a set of NIR spectra of oleyl alcohol in the pure liquid state under temperature changes. The 2D NIR analysis enhances the spectral resolution and simplifies the spectra with overlapped bands. For example, it was found that a band at 7090 cm−1, arising from the first overtone of an OH stretching mode of the monomeric alcohol, consists of two bands due to the rotational isomerism of the free OH group. The second example deals with the temperature-dependent NIR spectral changes of N-methylacetamide (NMA). The close-up view of 2D NIR correlation spectra of NMA, obtained at narrow spectral and temperature windows, enabled us to propose not only band assignments in the 6800–6050 cm−1 region, where the first overtones of stretching modes of free, free-end and hydrogen-bonded NH groups were expected to appear, but also a detailed mechanistic picture of the thermally-induced dissociation of NMA for each temperature range. A 2D NIR study of premelting behaviour and hydrogen bonds of Nylon 12 is discussed as the third example. The asynchronous 2D NIR correlation spectrum of Nylon 12 obtained from 30 to 150°C in the 6900–6100 cm−1 region indicated that the amide group with a free carbonyl oxygen appears first and then the unassociated free amide and amide with free NH follow as the temperature is increased. The asynchronous spectrum in the 6000–5500 cm−1 region, where the first overtones of the CH2 stretching modes are expected to appear, suggested that a substantial amount of disordered or dissociated components start appearing before the disappearance of more ordered components. It seemed that they appear as the premelting precursors (or even possibly as the indirect cause) to the precipitous decrease of the ordered components associated with the melting of Nylon 12 occurring at a much higher temperature.

Two-Dimensional Raman Correlation Spectroscopy Study of Poly[(R)-3-hydroxybutyrate-co-(R)-3-hydroxyhexanoate] Copolymers

2017 ◽  
Vol 71 (7) ◽  
pp. 1427-1431 ◽  
Author(s):  
Isao Noda ◽  
Anjan Roy ◽  
James Carriere ◽  
Brian J. Sobieski ◽  
D. Bruce Chase ◽  
...  
Keyword(s):  
Correlation Spectroscopy ◽  
Two Dimensional ◽  
Spectroscopy Study ◽  
Raman Correlation Spectroscopy

scholarly journals Two-Dimensional Near-Infrared Correlation Spectroscopy Study of Ovalbumin in Acidic pH Region

2001 ◽  
Vol 41 (supplement) ◽  
pp. S44
Author(s):  
K. Murayama ◽  
T. Negawa ◽  
T. Hayashi ◽  
K. Kuwata ◽  
S. Era ◽  
...  
Keyword(s):  
Near Infrared ◽  
Correlation Spectroscopy ◽  
Acidic Ph ◽  
Two Dimensional ◽  
Spectroscopy Study
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