Computational chemistry infrared spectroscopy

Kurt Varmuza was bom in 1942 in Vienna, Austria. He studied chemistry at the Vienna University of Technology, Austria, where he wrote his doctoral thesis on mass spectrometry and his habilitation, which was devoted to the field of chemometrics. His research activities include applications of chemometric methods for spectra-structure relationships in mass spectrometry and infrared spectroscopy, for structure-property relationships, and in computer chemistry, archaeometry (especially with the Tyrolean Iceman), chemical engineering, botany, and cosmo chemistry (mission to a comet). Since 1992, he has been working as a professor at the Vienna University of Technology, currently at the Institute of Chemical Engineering. 

Recently, introductory books about chemometrics have been published by R. G. Brereton, Chemometrics—Data Analysis for the Laboratory and Chemical Plant (Brereton 2006) and Applied Chemometrics for Scientists (Brereton 2007), and by M. Otto, Chemometrics—Statistics and Computer Application in Analytical Chemistry (Otto 2007). Dedicated to quantitative chemical analysis, especially using infrared spectroscopy data, are A User-Friendly Guide to Multivariate Calibration and Classification (Naes et al. 2004), Chemometric Techniques for Quantitative Analysis (Kramer 1998), Chemometrics A Practical Guide (Beebe et al. 1998), and Statistics and Chemometrics for Analytical Chemistry (Miller and Miller 2000). 

Infrared (IR) spectroscopy was the first modern spectroscopic method which became available to chemists for use in the identification of the structure of organic compounds. Not only is IR spectroscopy useful in determining which functional groups are present in a molecule, but also with more careful analysis of the spectrum, additional structural details can be obtained. For example, it is possible to determine whether an alkene is cis or trans. With the advent of nuclear magnetic resonance (NMR) spectroscopy, IR spectroscopy became used to a lesser extent in structural identification. This is because NMR spectra typically are more easily interpreted than are IR spectra. However, there was a renewed interest in IR spectroscopy in the late 1970s for the identification of highly unstable molecules. Concurrent with this renewed interest were advances in computational chemistry which allowed, for the first time, the actual computation of IR spectra of a molecular system with reasonable accuracy. This chapter describes how the confluence of a new experimental technique with that of improved computational methods led to a major advance in the structural identification of highly unstable molecules and reactive intermediates. 

Structural study of polysaccharides and other carbohydrates in solution or in the amorphous state has been significantly enhanced through the application of Fourier-transform, infrared spectroscopy. Among the advantages of this method may be mentioned the high quality of the spectra, and the in-house ability to interact with the computer, so that the digitized spectra may be stored and manipulated in such a way that additional information is obtained. The application of F.t.-i.r. spectroscopy in the field of carbohydrate chemistry and biochemistry is still in its infancy,182 but... 

In the last three decades, nuclear magnetic resonance has become a powerful tool for investigating the structural and physical properties of matter. Today, nuclear magnetic resonance is the physical method most widely used in analytical chemistry. For special applications, e.g. relaxation time measurements, there is available a variety of modifications of the basic nuclear magnetic resonance experiments such as pulse and spin-echo methods. In the course of this development and when electronic computers were provided at a reasonable price, Fourier transform spectroscopy was applied to nuclear magnetic resonance in the middle of the sixties. At that time, Fourier methods were already used to a large extent in far infrared spectroscopy (see Refs. and references cited therein). 

Chemometrics Multivariate View on Chemical Problems Combinatorial Chemistry Factual Information Databases Fuzzy Methods in Chemistry Infrared Data Correlations with Chemical Structure Infrared Spectra Interpretation by the Characteristic Frequency Approach Inorganic Chemistry Databases Inorganic Compound Representation NMR Chemical Shift Computation Ab Initio NMR Chemical Shift Computation Structural Applications NMR Data Correlation with Chemical Structure Online Databases in Chemistry Spectroscopy Computational Methods Standard Exchange Formats for Spectral Data Structure and Substructure Searching Structure Determination by Computer-based Spectrum Interpretation Structure Generators Synthesis Design. 

The mechanism of the activation of H2O2 by TS-1 and related catalysts has been the subject of much research using spectroscopic and computational techniques. This has centred on the nature of the active site and its mode of reaction with H2O2, solvents and the organic substrates. Work to elucidate the structure of the active site has concentrated on the coordination chemistry of the titanium. X-ray and neutron diffraction studies, coupled with X-ray absorption, infrared and Raman spectroscopies, give evidence that most of the Ti(IV) in calcined TS-1, in the absence of any adsorbate molecules, is in tetrahedral coordination. Upon addition of one molecule of water, one of the Ti-OSi bonds is hydrolysed and the titanium adopts tetrahedral coordination as Ti(0Si)30H. Addition of a further water molecule gives rise to a pentaco-ordinated titanium. ... 

K. S. Kalasinsky and G. R. Lightsey, "Quanitative Analysis of Cellulosic Filler Surface Chemistry Using Infrared Reflectance Spectroscopy and Computer Spectral Addition (In press). F. Lowery and G. R. Lightsey, Un-Published Data, Dept, of Chem. Engr., Miss. State Univ. (1980). 

---