Synthesis of symmetrical cyanine dyes with two N-ammonioalkyl groups

Synthesis of new symmetrical mono-, tri-, and pentamethine cyanine dyes with two N-ammonioalkyl substituents was developed. In the last step of the synthesis, conditions for the removal of the phthalimide protecting group in cyanine dyes using hydrazine monohydrate and an ethanol solution of MeNH2 were selected. The obtained dyes with ammonium groups capable of hydrogen bonding are promising as components of light-sensitive supramolecular systems.