DNA/BSA binding study of iminodiacetate-based gallium(III) complexes

Gallium(III) complexes have emerged as promising candidates in bioinorganic chemistry due to their structural versatility, stability, and ability to mimic iron in biological systems, which allows them to interact selectively with key biomolecules. Motivated by these properties, we synthesized two novel gallium(III) complexes, Na[Ga(ida)₂]·2H₂O (1) and K[Ga(ida)₂]·3H₂O (2), employing iminodiacetate (ida^2–) as the ligand. The synthesis of these complexes was carried out in aqueous solution by reacting GaCl₃ with iminodiacetic acid (H₂ida) at 80 °C for 4 h in the presence of NaOH or KOH, respectively. Their structures were determined using IR and NMR (¹H and ¹³C) spectroscopy and further confirmed through single-crystal X-ray diffraction analysis. Building on this structural work, we investigated their interactions with bovine serum albumin (BSA) and calf thymus DNA (ct-DNA) using fluorescence emission spectroscopy to assess their binding affinity towards these biologically important molecules. Since serum albumin consists of three main domains (I–III), each subdivided into two subdomains (A and B), fluorescence competition experiments with site-specific markers were also performed to identify the preferred binding sites of the complexes. Eosin Y served as a marker for site I (subdomain IIA), ibuprofen for site II (subdomain IIIA), and digitoxin for site III (subdomain IB).