The use of UV, FT-IR and Raman spectra for the identification of the newest penem analogs: Solutions based on mathematic procedure and the density functional theory

The application of ultraviolet, FT-IR and Raman spectra was proposed for identification studies of the newest penem analogs (doripenem, biapenem and faropenem). An identification of the newest penem analogs based on their separation from related substances was achieved after the application of first derivative of direct spectra in ultraviolet which permitted elimination of overlapping effects. A combination of experimental and theoretical studies was performed for analyzing the structure and vibrational spectra (FT-IR and Raman spectra) of doripenem, biapenem and faropenem. The calculations were conducted using the density functional theory with the B3LYP hybrid functional and 6-31G(d,p) basis set. The confirmation of the applicability of the DFT methodology for interpretation of vibrational IR and Raman spectra of the newest penem analogs contributed to determination of changes of vibrations in the area of the most labile bonds. By employing the theoretical approach it was possible to eliminate necessity of using reference standards which – considering the instability of penem analogs – require that correction coefficients are factored in.

Graphical abstract.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► The FT-IR and Raman spectra of doripenem, biapenem, faropenem were recorded. ► The UV spectra of doripenem, biapenem, faropenem were studied. ► Theoretical approach to spectra based on DFT method.