Structure of Protonated Baclofen [AuCl₄]⁻, Theoretical Elucidation and Biological Studies

ABSTRACT Baclofen (3‐(4‐chlorophenyl)butyric acid, HBAC), a useful medicine of CNS depressant, muscle relaxant, and GABA agonist, has been used to isolate Au (III) ionic solid, [H 2 BAC] + [AuCl 4 ] − ( 1 ). The confirmed structure of 1 is established by the single crystal X‐ray diffraction measurements along with various other physicochemical studies. The anticancer activity of 1 is evaluated on MCF‐7, HeLa, MDA‐MB‐231, A549 cancer cells and has been compared with human normal lung fibroblast cell line (WI‐38) and kidney epithelial cell line NKE. The results have been compared with Cisplatin as a standard reference. The toxicity of 1 is accounted from the MTT assay. Notably, the complex 1 has exhibited higher efficacy in inhibiting the proliferation of MCF‐7 (IC 50 : 11.36 ± 1.58 μM) compared to other cancer cells, such as HeLa (IC 50 : 18.23 ± 2.31 μM), A549 (IC 50 : 32.09 ± 2.17 μM), and MDA‐MB‐231 (IC 50 : 27.07 ± 2.42 μM). A thorough examination of Hirshfeld surfaces and fingerprint plots were used for the comparison of intermolecular interactions, which are critical in the formation of various supramolecular designs. Using the crystallographic parameters of complex 1 , DFT computation determines the energy gap (ΔE = E HOMO – E LUMO ), 2.50 eV, which is within the range of semiconducting materials and may help for anticarcinogenic action.