Two-Dimensional Infrared (2D IR) Spectroscopy: Theory and Applications

Abstract

A novel concept in vibrational spectroscopy called two-dimensional infrared (2D IR) spectroscopy is described. In 2D IR, a spectrum defined by two independent wavenumbers is generated by a cross-correlation analysis of dynamic fluctuations of IR signals induced by an external perturbation. 2D IR spectra are especially suited for elucidating various chemical interactions among functional groups. Notable features of the 2D IR approach are: simplification of complex spectra consisting of many overlapped peaks; enhancement of spectral resolution by spreading peaks over the second dimension; and establishment of unambiguous assignments through correlation analysis of bands selectively coupled by various interaction mechanisms. The procedure for generating 2D IR correlation spectra and the properties of the 2D spectra are discussed in detail. Examples of 2D IR spectra are presented for atactic polystyrene and the proteinacious component of human stratum corneum to demonstrate the utility of this technique.

Structural analysis of natural killer cell receptor protein 1 (NKR-P1) extracellular domains suggests a conserved long loop region involved in ligand specificity

“…The main advantage of 2DCoS is that it allows enhancement of spectral resolution by spreading overlapping bands over a second dimension. In addition, sign analysis of the correlation peaks in the 2D maps may improve band assignment and permit establishment of a sequence of events during the perturbation process [57][58][59].…”

“…Application of these so called Noda rules [57][58][59] to mNKR-P1C second derivative FTIR spectra indicate the following sequential order of structural changes. Changes in -turns occur first, followed by an increase in -sheet content, then changes in -helices followed by changes in loops.…”

Potential of two-dimensional correlation spectroscopy in analyses of NIR spectra of biological fluids. I. Two-dimensional correlation analysis of protein and fat concentration-dependent spectral variations of milk

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T wo-dimensional (2D) corre l ation spectro s c o py has recently received keen interest because it is a totally n ew and powerful spectral analytical method [1][2][3][4]. The 2D correlation spectroscopy enables us to obtain spectral information not readily accessible from one-dimensional spectra by spreading spectral peaks over the second dimension [1][2][3][4][5][6][7].

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“…The 2D correlation spectroscopy enables us to obtain spectral information not readily accessible from one-dimensional spectra by spreading spectral peaks over the second dimension [1][2][3][4][5][6][7]. Band assignments and studies of inter-and intramolecular interactions become easier by selective correlations between various bands in synchronous and asynchronous 2D correlation spectra.…”

“…O ri ginal 2D corre l ation spectro s c o py was proposed by Noda [1,2] in 1986 as 2D correlation mid-infrared (MIR) * Cor respondence and reprints.…”