Synthesis and photophysical characterisation of 3-bromo-4-dimethylamino-1,8-naphthalimides and their evaluation as agents for antibacterial photodynamic therapy

Abstract

Through the peripheral modification of a first-generation polypropylene amine dendrimer two new photoactive dendrimers containing 4-dimethylamino-1,8-naphthalimide (3) and 3-bromo-4-dimethylamino-1,8-naphthalimide (4), have been obtained. Photophysical and spectral characteristics of these dendrimers were investigated in two organic solvents. We found that they absorb light in the visible spectral region and emit yellow-green fluorescence. Antimicrobial activity of dendrimers against pathogenic microorganisms has been investigated in solution and after deposition on a cotton fabric. For the first time, 1,8-naphthalimide derivatives have been tested as active components in antibacterial photodynamic therapy. To clarify the dendrimer effect, the results obtained were compared with those from two monomeric 1,8-naphthalimides (1 and 2) containing the same substitutes in the chromophore system. Cytotoxicity and antiviral activity of the dendrimers were also assessed.