Oxidative degradation process of organic materials in wastewater is an area of significant current interest. In the case of commercial textile dyes, little is known about the structures of the actual products that can form once a dye has been submitted to oxidative conditions. Here, a product analysis approach was applied to identify some of the major early degradation products of Uniblue A (UBA) when reacted with peroxydisulfate (PDS). UBA is the vinyl sulfone form and major wastewater constituent of the commercial anthraquinone textile dye C.I. Reactive Blue 19. Using NMR, LC-MS, and Raman, four reaction products could be identified, and possible reaction pathways are discussed.

Four generations of poly(aryl ether) monodendrons labeled with pyrene at the focus were synthesized and characterized by a combination of NMR, size-exclusion chromatography with light scattering detection, and electronic spectroscopy. The monodendrons were then studied by magnetic resonance and fluorescence techniques. Translational diffusion coefficients in THF-d 8, acetonitrile-d3, and cyclohexane-d12 were measured by pulsed-field-gradient NMR and ranged from 2.2 × 10 -5 cm 2 /s for methoxypyrene in acetonitrile to 3.4 × 10 -6 cm 2 /s for the fourth generation monodendron in THF. Molecular radii were calculated from the diffusion coefficients by the Stokes-Einstein equation. In THF, the radii increased from 2.8 Å for methoxypyrene to 14 Å for the fourth generation monodendron. In acetonitrile the radii were smaller, increasing from 2.7 Å for methoxypyrene to 5.4 Å for the third generation monodendron. In both solvents, a change in solution structure between the second and third generation monodendrons was observed in the diffusion data. The rate of fluorescence quenching by molecular oxygen was measured for the pyrene-labeled monodendrons in THF, acetonitrile, and cyclohexane and was found to decrease for monodendrons of increasing generation. This decrease cannot be fully explained by the slower diffusion of the larger monodendrons. Several simple models for the reduced quenching rate of the pyrene chromophore were developed. These models suggest that the increased density of the larger monodendrons provides a more effective barrier to diffusing dioxygen.

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Diffusion coefficients were measured by pulsed-field gradient NMR for low molecular weight linear polystyrenes in THF and for a broader molecular weight range of linear polystyrenes in chloroform and for PAMAM dendrimers up to generation 4 in methanol. Radii were calculated from the measured diffusion coefficients using the Stokes-Einstein relationship. The linear polystyrenes displayed a relationship between radius and molecular weight that followed the expected power law. From simple theoretical considerations, the dendritic polymers were expected to follow a logarithmic relationship between radius and molecular weight. The PAMAM dendrimers gave reasonable fits to both a power law and a logarithmic relationship from generation 0 to generation 3 (the power law gave a slightly better fit), but displayed a turnover with generation 4, which gave a smaller Stokes radius than generation 3. These results were compared with earlier results from poly (aryl ether) monodendrons, where the relationship was ambiguous between a power law and a logarithmic relationship.