A fluorescence study of new angular polycyclic blue light-emitting pyrazolo[3,4-h][1,6]naphthyridine and their interaction with bovine serum albumin (BSA).

The blue light-emitting pyrazolo[3,4-h][1,6]naphthyridines has been synthesized by Friedländer condensation of 4-amino-3-(4-phenyl)-1-phenyl-1H-pyrazolo[3,4-b]pyridine-5-carbaldehyde (o-aminoaldehyde) 1 with different cyclic ketones and 1,3-diketones. The synthesized angular polycyclic naphthyridine derivatives were studied for Semi-empirical, thermal, UV-vis and fluorescence spectroscopic properties on binding with bovin serum albumin (BSA). These fluorescence properties together with the neutral, hydrophobic nature of these compounds make these fluorophores good fluorescence probe for studying the micropolarity of proteins like BSA and in general the ligand-protein interactions. All of them displays bright absorption at 394 nm & emission in visible region (491 nm). Quantum yields of all synthesized compounds were calculated.