Infrared spectroscopy conjugation effects

To detect adulteration of wine. Bums et al. (2002) found that the ratios of acetylated to p-coumaroylated conjugates of nine characteristic anthocyanins served as useful parameters to determine grape cultivars for a type of wine. Our laboratory utilized mid-infrared spectroscopy combined with multivariate analysis to provide spectral signature profiles that allowed the chemically based classification of antho-cyanin-containing fruits juices and produced distinctive and reproducible chemical fingerprints, making it possible to discriminate different juices. " This new application of ATR-FTIR to detect adulteration in anthocyanin-containing juices and foods may be an effective and efficient method for manufacturers to assure product quality and authenticity. 

Analysis of Cure. Infrared spectroscopy was utilized to examine film cure and the effect of stabilizers upon the cure of the epoxy acrylate. Pre-cured material has absorptions at 1635, 1410 and 810 cm-1 which clearly diminish after the resin is UV-irradiated (Figure 6). The 1635 cm-1 absorption can be assigned to the carbon-carbon stretch of an olefinic bond in conjugation with a carbonyl group the 1410 cm-1 can be assigned to the CH2 in-plane deformation of a vinylic group. The 810 cm-1 can also be assigned to some aspect of vinylic... 

Further work involved the creation of a conjugated polymer with quaternary ammonium side chains and an alternating phenylene-ethynylene-thiophene-ethynylene backbone (C28). ° These polymers were also physisorbed onto silica beads. As with the other polymers, they showed the ability to attract and kill bacteria. Unlike previous polymers, however, light exposure appeared to inhibit bacterial growth. Furthermore, free polymer in solution appeared to be far more effective at killing P. aeruginosa than previous polymers. Infrared spectroscopy studies showed that the... 

In a study of PITN with in situ and ex situ resonance Raman spectroscopy combined with a vibrational analysis, Wallnofer et al. [1055] obtained further details of PITN in its various doped and undoped states. A theoretical foundation for the interpretation of vibrational spectra of PITN was provided by Faulques et al. [1056]. Their results were taken into consideration in e previous discussion of Raman and infrared spectra. Zerbi et al. [1057] reinvestigated PITN prepared chemically with Raman spectroscopy er situ because they believed that previous results were inconclusive. Their results, based on the effective conjugation coordinate, imply that PITN in its electronic ground state is present in the quinoid form. 

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