Ternary oxidovanadium(IV) complexes of curcumin (Hcur), dipicolylamine (dpa) base, and its derivatives having pendant noniodinated and di-iodinated boron-dipyrromethene (BODIPY) moiety (L and L, respectively), namely, [VO(dpa)(cur)]ClO (1), [VO(L)(cur)]ClO (2), and [VO(L)(cur)]ClO (3) and their chloride salts (1a-3a) were prepared, characterized, and studied for anticancer activity. The chloride salts were used for biological studies due to their aqueous solubility. Complex 1 was structurally characterized by single-crystal X-ray crystallography. The complex has a VO moiety bound to dpa ligand showing N,N,N-coordination in a facial mode, and curcumin is bound in its mono-anionic enolic form. The V-O(cur) distances are 1.950(18) and 1.977(16) Å, while the V-N bond lengths are 2.090(2), 2.130(2), and 2.290(2) Å. The bond trans to V═O is long due to trans effect. The complexes are stable in a solution phase over a long period of time of 48 h without showing any apparent degradation of the curcumin ligand. The diiodo-BODIPY ligand (L) or Hcur alone showed limited solution stability in dark. The emissive BODIPY (L) containing complex 2a showed preferential mitochondrial localization in MCF-7 cells in cellular imaging experiments. The cytotoxicity of the complexes was studied by MTT assay. The BODIPY complex 3a showed excellent photodynamic therapy effect in visible light (400-700 nm) giving IC values of 2-6 μM in HeLa and MCF-7 cancer cells, while being less toxic in dark (∼100 μM). The cell death was apoptotic in nature involving reactive oxygen species (ROS). Mechanistic data from pUC19 DNA photocleavage studies revealed photogenerated ROS as primarily O from the BODIPY moiety and ·OH radicals from the curcumin ligand.

The ruthenium­(II) complexes [RuCl­(L1)­(L3)]Cl (1), [RuCl­(L1)­(L4)]­Cl (2), [RuCl­(L2)­(L4)]Cl (3), [RuCl­(L1)­(L5)]Cl (4), and [RuCl­(L2)­(L5)]Cl (5) of NNN-donor dipicolylamine (dpa) bases (L4, L5) having BODIPY (boron-dipyrromethene) moieties, NN-donor phenanthroline derivatives (L1, L2), and benzyldipicolylamine (bzdpa, L3) were prepared and characterized by spectroscopic techniques and their cellular localization/uptake and photocytotoxicity studied. Complex 1, as its PF6 salt (1a), has been structurally characterized with help of a single-crystal X-ray diffraction technique. It has a RuN5Cl core with the Cl bonded trans to the amine nitrogen atom of bzdpa. The complexes showed intense absorption spectral bands near 500 nm (ε ≈ 58000 M–1 cm–1) in 2 and 3 and 654 nm (ε ≈ 80000 M–1 cm–1) in 4 and 5 in 1/1 DMSO/DPBS (v/v). Complex 5 having biotin and PEGylated-disteryl BODIPY gave a singlet oxygen quantum yield (ΦΔ) of ∼0.65 in DMSO. Complex 5 exhibited remarkable PDT (photodynamic therapy) activity (IC50 ≈ 0.02 μM) with a photocytotoxicity index (PI) value of >5000 in red light of 600–720 nm in A549 cancer cells. The biotin-conjugated complexes showed better photocytotoxicity in comparison to nonbiotinylated analogues in A549 cells. The complexes displayed less toxicity in HPL1D normal cells in comparison to A549 cancer cells. The emissive BODIPY complexes 3 and 5 (ΦF ≈ 0.07 in DMSO) showed significant mitochondrial localization.

Mixed-ligand oxidovanadium(IV) β-diketonates having NNN-donor dipicolylamine-conjugated to boron-dipyrromethene (BOD-IPY 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-1,3propanedione, 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 nonemissive 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.

Two multichromophoric homoleptic ruthenium(II) complexes [Ru(tpy-BODIPY)2]Cl2 (complexes 1 and 2, tpy = 4-phenyl-2,2:6,2-terpyridine, BODIPY = boron-dipyrromethene) were prepared, characterized and their phototherapeutic activity and bioimaging properties studied. The complexes having...

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