Synthesis and photophysical evaluations of fluorescent quaternary bipyridyl-1,8-naphthalimide conjugates as nucleic acid targeting agents

A family of organic molecules containing the DNA intercalating chromophores, 4-nitro- and 4-amino 1,8-naphthalimide, conjugated to a diquat derivative by an ‘orthogonal’ phenyl spacer have been prepared and characterised. Their binding interactions with double-stranded DNA were studied by a variety of spectroscopic techniques. These charged organic compounds are found to exhibit excellent binding affinities to DNA with binding constants comparable to those exhibited by metal complexes.