Two [Ru(phen) dppz] derivatives (phen=1,10-phenantroline, dppz=dipyrido[3,2-a:2',3'-c]phenazine) with different functional groups on the dppz ligand [dppz-7,8-(OMe) (1), dppz-7,8-(OH) (2)] have been synthesized, characterized and investigated as photosensitizers (PSs) for photodynamic therapy (PDT) against cancer. Both complexes showed intense red phosphorescence and promising singlet oxygen ( O ) quantum yields of 75 % (1) and 54 % (2) in acetonitrile. Complex 1 (logP =-0.52, 2.4 nmol Ru per mg protein) was found to be more lipophilic, having also a higher cellular uptake efficiency compared to 2 (logP =-0.20, 0.9 nmol Ru per mg protein). Complex 1 localized evenly in HeLa cells whereas 2, was mainly visualized in the cell membrane by confocal microscopy. In the dark, complex 1 (IC =36.5 μm) was found to be more toxic than complex 2 (IC >100 μm) on a HeLa cells monolayer. Importantly, in view of PDT applications, both complexes were found to be non-toxic in the dark towards multicellular HeLa spheroids (IC >100 μm). Upon one-photon irradiation (420 nm, 9.27 J cm ), 1 exhibited higher phototoxicity (IC =3.1 μm) than 2 (IC =16.7 μm) on HeLa cell monolayers. When two-photon irradiation (800 nm, 9.90 J cm ) was applied, only 1 (IC =9.5 μm) was found to be active toward HeLa spheroids. This study demonstrates that the functional group on the intercalative ligand has a strong influence on the cellular localization and anticancer activity of Ru polypyridyl complexes.

Efficient light detection in the near-infrared (NIR) wavelength region is central to emerging applications such as medical imaging and machine vision. An organic upconverter (OUC) consists of a NIR-sensitive organic photodetector (OPD) and an visible organic light-emitting diode (OLED), connected in series. The device converts NIR light directly to visible light, allowing imaging of a NIR scene in the visible. Here, we present an OUC composed of a NIR-selective squaraine dye-based OPD and a fluorescent OLED. The OPD has a peak sensitivity at 980 nm and an internal photon-to-current conversion efficiency of ∼100%. The OUC conversion efficiency (0.27%) of NIR to visible light is close to the expected maximum. The materials of the OUC multilayer stack absorb very little light in the visible wavelength range. In combination with an optimized semitransparent metal top electrode, this enabled the fabrication of transparent OUCs with an average visible transmittance of 65% and a peak transmittance of 80% at 620 nm. Visibly transparent OUCs are interesting for window-integrated electronic circuits or imaging systems that allow for the simultaneous detection of directly transmitted visible and NIR upconverted light.

A chemistry laboratory experiment using everyday items and readily available chemicals is described to introduce advanced high school students and undergraduate college students to porous polymer membranes. In a three-step manufacturing process, a membrane is produced at room temperature. The filtration principle of the membrane is then illustrated by filtering solutions containing pigmentary watercolor or food coloring. A comparison of the filtration results shows that insoluble watercolor pigments are too large to pass the pores of the membrane and are successfully rejected by the membrane, whereas the food coloring is completely soluble in water and easily passes the membrane. The laboratory experiment can be performed in a 2 h activity and serves the purpose of (1) exposing students to a new and interesting field of material science. It (2) makes them familiar with porous membranes for the production of safe drinking water and (3) introduces them to a template-removal technique utilizing acid/base theory. There were 52 advanced high school students and 55 high school teachers in Switzerland who already successfully performed the laboratory experiment and found the activity engaging and motivating.