2-Substituted perimidines: Zwitterionic tauterism in solid state, substituent effect on their crystal packing and biological activity

•Synthesis of five 2-subtituted 1H-perimidines bearing an acidic aliphatic tail are reported.•Influence of the substituent on the electronic and biological properties.•Zwitterionic tautomerism in the solid state according to single crystal X-ray diffraction.•Influence of the substituent and water inclusions on the crystal packing.•Formation of the 3D network complexes.