Detection of Copper(II) in Water by Methylene Blue Derivatives

Two novel phenothiazin-5-ium derivatives bearing cyclam moieties ( 3 a⁺ and 3 b⁺ ) were synthesized and investigated as Cu²⁺ sensors. Both ligands show intense spectral changes in the presence of Cu²⁺ in aqueous solutions. The high molar extinction coefficient of the chromophore allows both naked eye detection and spectrophotometric quantitative determination of the cation at a micromolar-concentration scale. 3 a⁺ was found to outperform 3 b⁺ , showing negligible spectral changes in the presence of excesses of other metal cations.     

Synthesis of a Photostable Near‐Infrared‐Absorbing Photosensitizer for Selective Photodamage to Cancer Cells

A new class of near‐infrared (NIR)‐absorptive (>900 nm) photosensitizer based on a phenothiazinium scaffold is reported. The stable solid compound, o‐DAP, the oxidative form of 3,7‐bis(4‐methylaminophenyl)‐10H‐phenothiazine, can generate reactive oxygen species (ROS, singlet oxygen and superoxide) under appropriate irradiation conditions. After biologically evaluating the intracellular uptake, localization, and phototoxicity of this compound, it was concluded that o‐DAP is photostable and a potential selective photodynamic therapy (PDT) agent under either NIR or white light irradiation because its photodamage is more efficient in cancer cells than in normal cells and is without significant dark toxicity. This is very rare for photosensitizers in PDT applications.