Synthesis and fluorescence investigation of differently substituted benzo[b][1,8]naphthyridines: interaction with different solvents and bovine serum albumin (BSA).

A series of benzo[b][1, 8]naphthyridines has been synthesized by Friedländer condensation of 2-aminoquinoline-3-carbaldehyde 1 (o-aminoaldehyde) with active methylenes in basic medium. The fluorescence spectroscopic properties of some representative compounds has been studied in different organic solvents; moreover interaction with bovine serum albumin (BSA) in phosphate buffer was examined by UV-vis and fluorescence spectroscopy. The effect of electron donor-acceptor substituents on fluorescence properties of benzo[b][1, 8]naphthyridines 13(a-n) has been investigated along with their fluorescent quantum yields.