Negative solvatochromism of a series of pyridinium phenolate betaine dyes with increasing steric hindrance

► Increasing torsion in 1a-e series results in more and more intense solvatochromism. ► The solvatochromism of 1e approaches the one exhibited by ET(30). ► The two tert-butyl groups protect partially 1a-e from hydrogen bonding with hydroxylic solvents. ► The relative contribution of (non) specific interactions of 1a-e with solvents is discussed.