Synthesis, spectral properties and antimicrobial activity of a new cationic water-soluble pH-dependent poly(propylene imine) dendrimer modified with 1,8-naphthalimides.

A three-step synthesis was implemented to prepare a quaternary ammonium functionalized blue fluorescent poly(propylene imine) dendrimer modified with pyridinium salt of 4-acylamino-1,8-naphthalimide. The new cationic dendrimer absorbs in the ultraviolet light region and emits blue fluorescence. Its spectral characteristics in organic solvents and in an aqueous solution were studied. The influence of pH on the fluorescence intensity of the dendrimer was established with regard to its use as a pH sensor. The effect of hydroxyl ions on the absorption and fluorescence spectra in dry N,N-dimethylformamide was also investigated. The antimicrobial activity of the dendrimer was assessed against model pathogenic microorganisms in agar, liquid medium, and after its deposition on cotton fabric.