Light-induced catalytic and cytotoxic properties of phosphorescent transition metal compounds with a d ⁸ electronic configuration

Abstract

Transition metal compounds are well documented to have diverse applications such as in catalysis, light-emitting materials and therapeutics. In the areas of photocatalysis and photodynamic therapy, metal compounds of heavy transition metals are highly sought after because they can give rise to triplet excited states upon photoexcitation. The long lifetimes (more than 1 μs) of the triplet states of transition metal compounds allow for bimolecular reactions/processes such as energy transfer and/or electron transfer to occur. Reactions of triplet excited states of luminescent metal compounds with oxygen in cells may generate reactive oxygen species and/or induce damage to DNA, leading to cell death. This article recaps the recent findings on photochemical and phototoxic properties of luminescent platinum(II) and gold(III) compounds both from the literature and experimental results from our group.

New photosensitizers for photodynamic therapy

“…Rhodium compounds are often in the form of Rh(II)–Rh(II) bridged dimer compounds [58]. There is also evidence that some luminescent platinum(II) and gold(III) compounds can act as PSs [59]. …”

Photocatalytic properties of a new Z-scheme system BaTiO3/In2S3 with a core–shell structure

“…To this end, many strategies have been investigated to promote the charge separation, such as surface modication of photocatalysts with co-catalysts, 18 articially constructing heterojunctions and Z-scheme systems, [19][20][21] and introducing an electron capturing level in the band gap that would generate some defects in the metal oxide lattice and help to capture charge carriers, 22 or employing perovskites with an intrinsic electric dipole moment which can separate photo-induced electrons and holes, 23 or utilizing semiconductors with long lifetime of the excited triplet states. 24,25 Among the abovementioned strategies, Z-scheme mechanism is the most effective strategy to improve the photogenerated carrier separation ability. 26,27 The mechanism of Z-scheme is schematically demonstrated in Scheme 1.…”

Organoiridium Photosensitizers Induce Specific Oxidative Attack on Proteins within Cancer Cells

“…[5] Such complexes,t ogether with octahedral Ir III complexes,a re often luminescent and might be useful in theranostic procedures in which optical imaging is used to monitor the uptake of the sensitizer before subsequent irradiation then kills the cancer cells. [6] Ak ey advantage for metal complexes is the heavy-atom effect, which favors fast singlet-to-triplet intersystem crossing (ISC), thus giving longer excited-state lifetimes [7] and higher yields of 1 O 2 and/or other so-called reactive oxygen species (ROS). Theu se of red and near IR light (l = 600-1100 nm) also enhances the clinical application of PDT because of its low energy compared to either UV or visible light.…”