Characterization and solubility measurement and prediction of selected arylamines in hexane, methanol and benzene

The solubility of nine arylamine molecules in benzene, methanol and hexane was measured. These molecules were: triphenylamine, NN-(4-methyl phenyl) N,NN,N bis phenyl amine, NN-(3-methyl phenyl) N,NN,N bis phenyl amine, N,NN,N-bis(4-methyl phenyl) NN-phenyl amine, N,NN,N-bis(3-methyl phenyl) NN-phenyl amine, tritolylamine (N,N,NN,N,N-tris-(4-methylphenyl)amine), N,NN,N-bis-(4-methylphenyl)-NN-(3-methylphenyl)amine, N,NN,N-bis-(3-methylphenyl)-NN-(4-methylphenyl)amine, and N,N,NN,N,N-tris-(3-methylphenyl)amine. The solubility of these molecules was estimated using ideal solution theory, the Hildebrand equation, and UNIQUAC method. The ideal solution theory and the Hildebrand equation were not able to estimate solubility with high precision. However, UNIQUAC method was able to estimate the solubility with good accuracy. It was found that substitution of methyl group regardless of its number in aryl ring increases the solubility. In addition, meta-substitution always results in higher solubility regardless of the nature of the solvent. Physical properties, as well as electrochemical properties of these materials were also provided. Based on these data, the most promising candidates for device preparation should be: mTTA, TTA, mmmTTA, and mono-TPA. However, the only way to prove the above ranking would be to test the candidates in actual devices, which is outside the scope of this paper.