Vibrational spectra of phenylfluorone and their interpretation

Abstract

543.42+535.375.5 Fourier-transform IR absorption, Raman, and surface-enhanced Raman scattering spectra are presented for phenylfluorone, which is widely used as an analytical reagent in the photometric determination of high-valent metals from Groups III-VI of the Periodic Table. A geometric structure and vibrational frequencies for the phenylfluorone molecule were calculated using a quantum-mechanical density-functional method. An interpretation of its vibrational spectra was proposed for the first time. Spectral effects of phenylfluorone protonation have been studied. The geometry of phenylfluorone adsorbed on the surface of nanostructured silver films was examined.

Surface-enhanced Raman spectra of a complex of antimony with phenylfluorone and their interpretation

“…Upon formation of the metal complex, the double bond С 6 О 4 is broken, as a result of which its length increases by 0.037 Å compared to that calculated for the phenylfluorone molecule [17]. In this case, on the contrary, the bond С 7 О 5 becomes shorter by 0.025 Å.…”

“…As should be expected, the formation of the metal complex barely affects the geometry of the phenyl group and rings I and II. The bond lengths in them are approximately changed by 0.002-0.004 Å, and the angles are changed by 0.1°-0.3° as compared to the corresponding parameters obtained from the geome try optimization of the isolated phenylfluorone mole cule [17]. However, for ring III, changes are more con siderable.…”

“…5). As in the case of the phenylfluorone molecule [17], for its complex with Sb, a considerable violation of the symmetry of the condensed rings takes place. This is caused by a strong influence of the central oxygen atom О 3 rather than by the effect of the phenyl group, which is confirmed by an additional calculation of the geometry of the Sb-PF molecule.…”

“…A considerably smaller number of vibrations manifest themselves in the experimental SERS spec trum. To compare the experimental and calculated frequencies of Sb-PF, we used the detailed interpreta tion of the vibrational spectra of the phenylfluorone molecule that we previously proposed in [17]. To a considerable degree, this is determined by the close ness of the frequencies and the similarity of the modes of the majority of vibrations for phenylfluorone and its complex with antimony, in the first place those for which the natural coordinates of rings I and II change.…”

“…The vibra tional spectra of phenylfluorone have been studied in detail in our previous work [17]. This work is devoted to the study of the Raman spectra and SERS spectra of the complex of antimony with phenylfluorone.…”