Assessing molecular similarity/diversity of chemical structures by FT-IR spectroscopy.

FT-IR spectra have been investigated for their ability to distinguish compounds which are chemically diverse and to produce clusters of compounds which makes sense chemically. Principal component analysis (PCA) was applied to the analysis of a small database of FT-IR spectra. The effect of the data pretreatment step of log transformation on spectral data pattern was also visualized by using PCA plots. The method of sequential projection pursuit (SPP) was applied to detect inhomogeneities in the data. Finally, cluster analysis of these spectra, depending on unweighted pair-group average linkage, was carried out.