Solvato-, thermo- and photochromism in a new diazo diaromatic dye: 2-(p-tolyldiazenyl)naphthalen-1-amine

•A novel azo dye, 2-(p-tolyldiazenyl)naphthalen-1-amine (2tona) was synthesized.•Solvato- thermo- and photochromism of the compound were investigated.•The phenomena were interpreted in terms of specific solute/solvent interactions.•Azo-hydrazone & cis-trans isomerizations were related with the optical properties.•The compound appears as a good candidate for practical applications in materials sciences.