Dinuclear Gallium(III) Complex With 1,3-Propanediamine--Diacetate: Structural Characterization, Antimicrobial Activity, and DNA/BSA Interactions.

In this study, a tetradentate 1,3-propanediamine-diacetate (1,3-pdda) was utilized for the synthesis of a dinuclear gallium(III) complex, uns--[Ga(1,3-pdda)(-OH)] 2HO (). Complex was characterized using IR and NMR (H and C) spectroscopy, and its crystal structure was determined by single-crystal X-ray diffraction analysis. Both Ga(III) ions in Complex exhibit octahedral geometry, with each ion coordinated by two nitrogen and two oxygen atoms from the 1,3-pdda ligand, as well as two oxygen atoms from the bridging hydroxyl groups. IR and NMR (H and C) spectra were simulated using DFT methods, showing a high degree of correlation with experimental data. Hirshfeld surface analysis provided insights into intermolecular interactions, with H⋯O and H⋯H interactions contributing significantly to the crystal stability. The antimicrobial potential of Complex was evaluated alongside previously synthesized gallium(III) complexes, Na[Ga(1,3-pdta)]·3HO () and Ba[Ga(1,3-pndta)]·3HO (), with 1,3-pdta (1,3-propanediamine--tetraacetate) and 1,3-pndta ((±)-1,3-pentanediamine--tetraacetate), respectively. Among all the tested microbial species, the gallium(III) complexes have shown selective activity against PAO1 strain and were able to reduce pyocyanin production by 40-43% in the clinical isolate BK25H of this bacterium. Moreover, Complexes - can modulate the quinolone-mediated quorum sensing system in PAO1. Interaction studies with calf thymus DNA (ct-DNA) and bovine serum albumin (BSA) were conducted to evaluate the binding affinity and mode of interaction of Complex with key biomolecules, aiming to assess its potential for transport via serum proteins and its safety profile in terms of DNA interactions. Spectrofluorimetric experiments and molecular docking revealed that Complex binds strongly to the Site I on BSA, with weaker interactions at the Site II. While spectrofluorimetric studies showed that Complex has a slight affinity for minor groove binding or intercalation to ct-DNA, docking studies suggested some minor groove binding, especially in larger DNA sequences, with enhanced stabilization in 10-bp-DNA through hydrogen and carbon bonds.