Synthesis, photochemistry, and electrochemistry of ruthenium(II) polypyridyl complexes anchored by dicobalt carbonyl units

Ru(ii) and Ir(iii) phenanthroline-based photosensitisers bearing o-carborane: PDT agents with boron carriers for potential BNCT

Four novel transition metal-carborane photosensitisers were prepared by Sonogashira cross-coupling of 1-(4-ethynylbenzyl)-2-methyl-o-carborane (A-CB) with halogenated Ru(ii)- or Ir(iii)-phenanthroline complexes. The resulting boron-rich complexes with one (RuCB and IrCB) or two carborane cages (RuCB2 and IrCB2) were spectroscopically characterised, and their photophysical properties investigated. RuCB displayed the most attractive photophysical properties in solution (λ_em 635 nm, τ_T 2.53 μs, and φ_p 20.4%). Nanosecond time-resolved transient absorption studies were used to explore the ³MLCT nature of the triplet excited states, and the highest singlet oxygen quantum yields (Φ_Δ) were obtained for the mono-carborane-phenanthroline complexes (RuCB: 52% and IrCB: 25%). None of the complexes produce dark toxicity in SKBR-3 cells after incubation under photodynamic therapy (PDT) conditions. Remarkably, mono-carboranes RuCB and IrCB were the best internalised by the SKBR-3 cells, demonstrating the first examples of tris-bidentate transition metal-carborane complexes acting as triplet photosensitisers for PDT with a high photoactivity; RuCB or IrCB killed ∼50% of SKBR-3 cells at 10 μM after irradiation. Therefore, the high-boron content and the photoactive properties of these photosensitisers make them potential candidates as dual anti-cancer agents for PDT and Boron Neutron Capture Therapy (BNCT).

Polypyridyl Metallo-Organic Assemblies for Electrochromic Applications

Electrochromic films undergo optical changes in response to a redox stimulus. This intriguing phenomenon can be used for a wide range of applications, including smart windows, sensors, color displays, and memory elements. Despite the rapid progress of late, designing suitable electrochromic materials that offer low-cost production, appealing colors, and pronounced optical contrast with high efficiency, as well as long-term stability remains an engineering challenge. Solid-state metal oxides, liquid crystals, and organic polymers have been for many years the leading candidates, successfully making their way into commercial products. An alternative class of materials relies on metal complexes that can be processed from solution, offer a variety of colors, and have metal-centered stable and reversible redox chemistry. These metallo-organic materials possess a full range of electrochromic properties, including ultrahigh coloration efficiencies, and cyclic stability. Here, some of the recent scientific developments in this field are highlighted.

Synthesis and biological evaluation of copper(ii) pyrenethiosemicarbazone

A fluorescent Cu(ii) pyrenethiosemicarbazone complex exhibits enhanced DNA-cleavage and cytotoxicity on photoexcitation.