Fourier-transform infrared spectroscopy phase transitions

Varenne, A., Salmain, M., Brisson, C., and Jaouen, G. (1992) Transition metal carbonyl labeling of proteins. A novel approach to a solid-phase two-site immunoassay using Fourier transform infrared spectroscopy. Bioconjugate Chem. 3, 471-476. 

Combination of turbidity and conductivity, surface tension, Fourier-transformed infrared spectroscopy Nucleation during emulsion poljmierization of styrene, vinyl acetate, and methyl methacrylate continuous emulsion polymerization of methyl methacrylate, phase transition of polystyrene oligomers with Fourier-transformed infrared spectroscopy 93... 

Lewis, R.N., McElhaney, R.N. Membrane lipid phase transitions and phase organization studied by Fourier transform infrared spectroscopy. Biochim. Biophys. Acta 1828, 2347-2358 (2013)... 

A rate enhancement effect due to secondary nucleation has been identified in the solution-mediated transformation of the 7-phase of (i)-glutamic acid to its / -phase [82]. In this study, the kinetics of the polymorphic transition were studied using optical microscopy combined with Fourier transform infrared, Raman, and ultraviolet absorption spectroscopies. The crystallization process of n-hexatriacontane was investigated using micro-IR methodology, where it was confirmed that single... 

Phase transition can be followed by various physical techniques, such as differential scanning calorimetry (DSC), 2H-NMR, and electronic spin resonance (ESR), Fourier transform infrared (FTIR), and fluorescence spectroscopy. The various methods have been reviewed and their characteristics compared [97] (see also Chapter 3). 

Membrane fluidity is determined by following anisotropic rotation of fluorescent or spin probes. Liquid-crystalline (or fluid) to gel thermotropic phase transition of lipids (Figure 1) (cf. Section 3.1.1 l)in liposomes or intact biomembranes can be followed by Fourier transform infrared (FTIR) spectroscopy or differential scanning calorimetry (DSC). 

Akao et al. investigated the dehydration of trehalose dihydrate to yield form II under supercritical fluid conditions (21). Trehalose form II is a metastable crystalline form of trehalose anhydrate and can be readily converted into the dihydrate by exposure to a moist environment at room temperature (22). Trehalose form III is another anhydrous polymorph. The phase transition behavior, detected by Fourier transform infrared (FTIR) spectroscopy and confirmed by first-derivative euclidean distance analysis (FDE), was found to be dependent on the extraction time, temperature, and pressure of SCCO2. At 20 MPa, an increase in temperature from 70°C to 90°C augmented the dehydration rate of trehalose dihydrate. Thus it appears that a temperature higher than 70 °C at 20 MPa is required for dehydration of trehalose dihydrate. The polymorphic forms obtained at different temperatures and pressures are summarized in Table 1. 

Fourier transform infrared (FTIR) studies of the poly(bis-phenol A-carbonate) (PC) - poly(e-caprolactone) (PCL) blend system are presented. This is a complex blend system containing two crystallizable polymers, with large differences in crystalline melting points and glass transition temperatures (Tg), which are compatible in the amorphous state. FTIR spectroscopy has proven to be an excellent technique with which to study these blends. Evidence for the presence of specific chemical interactions between the two polymers in the amorphous state, which infers compatibility, has been obtained. Furthermore, the crystallization of the components of this blend system are readily followed at room and elevated temperatures. Solvent and polymer induced crystallization and the role of the effective Tg of the amorphous phase of the blends in the crystallization of PC is discussed. 

Multidimentional nonlinear infrared spectroscopy is used for identification of dynamic structures in liquids and conformational dynamics of molecules, peptides and, in principle, small proteins in solution (Asplund et al., 2000 and references herein). This spectroscopy incorporates the ability to control the responses of particular vibrational transitions depending on their couplings to one another. Two and three-pulse IR photon echo techniques were used to eliminate the inhomogeneous broadening in the IR spectrum. In the third-order IR echo methods, three phase-locked IR pulses with wave vectors kb k2, and k3 are focused on the sample at time intervals. The IR photon echo eventually emitted and the complex 2D IR spectrum is obtained with the use of Fourier transformation. The method was applied to the examination of vibrational properties of N-methyl acetamid and a dipeptide, acyl-proline-NH2.in D20. The 2D IR spectrum showed peaks at 1,610 and 1, 670 cm 1, the two frequencies ofthe acyl-proline dipeptide. Geometry and time-ordering of the incoming pulse sequence in fifth-order 2D spectroscopy is shown in Fig. 1.3. 

Fourier transform reflection-absorption infrared (RA-IR) spectroscopy is used to probe the structure and properties of sodium dodecyl sulfonate (C12S) monolayers that are self-assembled from dilute solution at an air-water interface. Recent optical models for the interpretation of signal intensity measurements are briefly reviewed. The methylene stretching peaks of C12S monolayers in the RA-IR spectra are used to determine die chain orientation, the surface concmtration and the conformational state of the alkyl chains. Conqiarisons are drawn between monolayers and C12S crystals. A phase transition is found as the concentration of C12S in the subphase below the monolayer is reduced. The effect of salt on the monolayers is presented. The infrared data is interpreted in terms of the surface tension behavior. 

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