Photocytotoxicity of Thiophene- and Bithiophene-Dipicolinato Luminescent Lanthanide Complexes

Abstract

New thiophene-dipicolinato-based compounds, K 2 nTdpa (n = 1, 2), were isolated. Their anions are sensitizers of lanthanide ion (Ln III ) luminescence and singlet oxygen generation ( 1 O 2 ). Emission in the visible and near-infrared regions was observed for the Ln III complexes with efficiencies (ϕ Ln ) ϕ Eu = 33% and ϕ Yb = 0.31% for 1Tdpa 2− and ϕ Yb = 0.07% for 2Tdpa 2− . The latter does not sensitize Eu III emission. Fluorescence imaging of HeLa live cells incubated with K 3 [Eu(1Tdpa) 3 ] indicates that the complex permeates the cell membrane and localizes in the mitochondria. All complexes generate 1 O 2 in solution with efficiencies (ϕ O 1 2 ) as high as 13 and 23% for the Gd III complexes of 1Tdpa 2− and 2Tdpa 2− , respectively. [Ln(nTdpa) 3 ] 3− (n = 1, 2) are phototoxic to HeLa cells when irradiated with UV light with IC 50 values as low as 4.2 μM for [Gd(2Tdpa) 3 ] 3− and 91.8 μM for [Eu(1Tdpa) 3 ] 3− . Flow cytometric analyses indicate both apoptotic and necrotic cell death pathways.

Tuning Excited-State Properties of [2.2]Paracyclophane-Based Antennas to Ensure Efficient Sensitization of Lanthanide Ions or Singlet Oxygen Generation

“…The generation of singlet oxygen was also observed with a quantum yield of 0.45, which is slightly lower than the A 2 antenna (Figure S11). This value is in the range of that observed in the literature. − ,− …”

“…A large variety of chromophores have been tested as antennae, such as polyaromatic dyes (anthracene or pyrene), , xanthene and coumarin derivatives, , π-conjugated chromophores (Michler ketone, tetrathiafulavalene, or dipolar dyes , ), coordination or organometallic complexes, , porphyrins, dithienylethene, murexide, , BODIPY dyes, , etc. On the other hand, besides porphyrinic ligands, − the research of original antenna ligand suitable for the sensitization of singlet oxygen is nowadays a very active area for application in photodynamic therapy (PDT) or in the design of multimodal theranostic probes combining therapy and diagnostics. − In this domain, the potentiality of the [2.2]-paracyclophane (pCp) moiety is completely unexplored.…”

Reversible trans-to-cis photoisomerization and irreversible photocyclization reactions of a Co-coordinated stilbene derivative on chiral di-β-diketonate lanthanide complexes

“…Lanthanide complexes have a wide range of applications in analytical chemistry, catalysis, medicine, and materials. 1–21 The development of lanthanide complexes with multi-output properties by external stimulation, especially with reversible output, is of great significance in the field of smart materials. 22–26 Of the various external stimuli, such light energy, electrical energy, and chemical energy, light is a clean energy stimulus source that has the characteristics of independent changeable modality, precise control, low energy, environmental benignity, and remote control.…”

Degradation of Model Compounds by 1O2-Generating Photosensitizer–Doped Membranes

“…While pursuing luminescent lanthanide complexes, which are also able to generate SO for theranostics applications, − we isolated a naphthalimide-based molecule, Nap-cbx, and its gadolinium complex, [Gd­(Nap-cbx) 3 ]­(NO 3 ) 3 (Scheme ). The insolubility of these two compounds in water precluded their screening as imaging and therapy agents.…”