The Solvatomagnetism of E_T(33) Betaine and of Its Phenolic Precursor

The ¹H and ¹³C NMR spectra of the N-(3,5-dichloro-4-hydroxyphenyl)- 2,4,6-triphenylpyridinium perchlorate and of its deprotonated betaine 4-(2,4,6-triphenylpyridinio)-2,6-dichlorophenolate (Wolfbeis's E_T(33) dye) were recorded in various solvents and analyzed in search of solvent-dependent shifts that characterize their solvatomagnetism, which was compared with the well-known UV-vis spectral behavior of this important solvatochromic dye. Although the NMR spectra of E_T(33) and its phenolic precursor in different solvents correlated only poorly with their UV-vis spectral responses, they provided valuable information on specific structural features and solute-solvent interactions that are not available from their UV-vis spectra.