Abstract Several 3, 5-methyl substituted fuchsones have been synthesized and characterized by means of UV and NMR spectroscopy as well as dipole moment measurements. Two basic types of behaviour of the longest wavelength band have been found for these derivatives in comparison to 2, 6-substituted analogues ie hypochromic effect and bathochromic shift. These effects can be attributed to a steric crowding of the C ( ...