Structurally Characterized BODIPY-Appended Oxidovanadium(IV) β-Diketonates for Mitochondria-Targeted Photocytotoxicity

摘要

Mixed-ligand oxidovanadium(IV) β-diketonates having NNN-donor dipicolylamine-conjugated to boron-dipyrromethene (BODIPY in L_(1)) and diiodo-BODIPY (in L_(2)) moieties, namely, [VO(L_(1))(acac)]Cl (1 ), [VO(L_(2))(acac)]Cl (2 ), and [VO(L_(1))(dbm)]Cl (3 ), where acac and dbm are monoanionic O,O-donor acetylacetone and 1,3-diphenyl-1,3-propanedione, were prepared, characterized, and tested for their photoinduced anticancer activity in visible light. Complexes 1 and 2 were structurally characterized as their PF_(6)~(–) salts (1a and 2a ) by X-ray crystallography. They showed V~(IV)N_(3)O_(3) six-coordinate geometry with dipicolylamine base as the facial ligand. The non-iodinated BODIPY complexes displayed absorption maxima at ～501 nm, while it is ～535 nm for the di-iodinated 2 in 10% DMSO–PBS buffer medium (pH = 7.2). Complexes 1 and 3 being green emissive (λ_(em), ～512 nm; λ_(ex), 470 nm; Φ_(F), ～0.10) in 10% aqueous DMSO were used for cellular imaging studies. Complex 3 localized primarily in the mitochondria of the cervical HeLa cells with a co-localization coefficient value of 0.7. The non-emissive diiodo-BODIPY complex 2 showed generation of singlet oxygen (Φ_(Δ) ≈ 0.47) on light activation. Annexin-V assay showed singlet oxygen-mediated cellular apoptosis, making this complex a targeted PDT agent.