Coordination competency of a flexible polyfunctional tripodal framework: an insight on solution thermodynamics and DFT studies

Chelation and solution thermodynamic stability of a tripodal hydroxypyranone-based chelator (tris[(5-hydroxy-4-oxo-pyran-2-yl)methyl]benzene-1,3,5-tricarboxylate), TBHPY, towards biologically relevant divalent metal ions:Cu(II), Fe(II), Ni(II), Co(II) and Zn(II) were studied by potentiometric and spectroscopic methods in 9:1 (H₂O:DMSO) medium. The metal ions formed ML, MLH_2, MLH, MLH_-2, and MLH_-1 type complexes with high formation constants. The ligand was explored for its application as a potential fluorimetric sensor and examined in the presence of various cations. Nearly twofold quenching was observed upon addition of Gd(III) to TBHPY. The experimental, spectroscopic and thermodynamic stability results were validated with the theoretical quantum mechanical calculations using density functional theory (DFT). The geometrical structures, electronic properties,and bonding behavior of the complexes are described in detail.