Spectroscopic studies dimethylsulfoxide

By utilizing the partial solubility of poly aniline in dimethylformamide (DMF), dimethylsulfoxide MSO) and tetrahydofuran (THF),and the more complete solubility in N-methylpyrrolidinone (NMP), films of chemically polymerized poly aniline have been prepared for spectroscopic studies. With DMF, DMSO and THF, it is necessary to remove insoluble materials in order to cast films from solution. Since we have recently found that this soluble part has low molecular weight, and usually consists of only about 20% of the total mass, there is a need to extend the spectroscopic studies to evaluate the effect of molecular weight on the principal absorption features. 

In 1997 the electronic absorption spectra of phenylnitrene" and its perfluorosubstituted analogues " were detected. Recently the kinetics of bimolecular reactions of the singlet fluoro-substituted arylnitrenes were studied using direct spectroscopic methods. The absolute rate constants of reaction of singlet perfluoroarylnitrene 16f and 16g with amines, pyridine and dimethylsulfoxide are presented in Table 11. 

Many studies have been made on the behavior of probe solutes in order to characterize the selective solvation in solvent mixtures, in particular depending on solvato-chromism. However, what is determined is the selective solvation of the probe, not of the binary solvent components with each other. It is conceivable that a spectroscopic investigation of a binary solvent mixture in the absence of a probe could be carried out if each component had a clear signal (absorption or fluorescence) at a characteristic exclusive wavelength. Such mixtures could be formamide + acetonitrile and formamide + dimethylsulfoxide, in which the C=0 bond stretching wave number of the hydrogen bond donor differs from the C=N and the S=0 bond stretching wave number of the acceptors (Alves and Santos 2007). 

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