Syntheses, Spectral Characterization, Computational Study of Some Novel Oxime Bridged Symmetric and Asymmetric Aluminum Dimers Containing Diols Along With Antimicrobial and Anticancer Activities

Symmetric and asymmetric dinuclear heteroleptic Aluminum (III) derivatives of the types [where {μ₁,₂ N, O}, {R = H(C1), CH₃(C2), Cl(C3), Br(C4)}] and [where R′ = R = H(C5); R′ = H, R = Cl(C6); R′ = H R = Br(C7); R′ = OCH₃, R = H(C8); R′ = OCH₃, R = CH₃(C9); R′ = OCH₃, R = Cl(C10); R′ = OCH₃, R = Br(C11)], containing tetra–tetracoordinated (C1–C5, C9–11) and tetra–hexacoordinated (C6, C7) aluminum atoms, respectively, were synthesized and characterized. The two successive substitution reactions of Al (OPrⁱ)₃ with diols and substituted oximes were carried out in unimolar ratio in refluxing benzene. Further, these complexes were characterized through IR, ¹H-NMR, ¹³C-NMR, and ²⁷Al NMR studies and mass spectrometry. The ²⁷Al NMR spectra of these complexes suggested the presence of tetra–tetra and tetra–hexacoordinated aluminum atoms. Synthesized complexes (C5–C11) and their respective ligands were assessed against Pseudomonas aeruginosa (gram negative) and Staphylococcus aureus (gram positive) for antibacterial activity and Fusarium oxysporum (human pathogen) and Aspergillus niger (plant pathogen) for antifungal activity. The representative compound C6 was tested in vitro against human colorectal carcinoma cell line (HCT116) and human breast cancer cell (MCF-7) lines to assess cytotoxicity through MTT assay. Moreover, the structure–activity-relationship among studied compounds has also been designed. Among all the synthesized compounds, C11 compound acquired the highest activity against gram-positive bacteria and C5 compound acquired the highest activity against plant pathogen for antifungal activity. Computational study was performed for the two compounds C5 and C8 along with their respective ligands LaH, LfH₂, LgH₂ in gas phase using B3LYP/631G* basis sets.