Enhanced and stabilized photoluminescence of perovskite cesium lead bromide nanocubes through ordered assemblies.

This work clarified the effects of self-assembly of perovskite cesium lead bromide (CsPbBr3) nanocubes (NCs) covered with didodecyldimethyl ammonium bromide (DDAB) on photoluminescence (PL) properties. Although the PL intensity of isolated NCs was weakened in the solid state even under inert conditions, the quantum yield of PL (PLQY) and the photostability of DDAB-covered NCs were drastically improved by the formation of two-dimensional (2D) ordered arrays on a substrate. The PLQY of the 2D arrays increased to ca. 60% by initial excitation illumination at 468 nm and was maintained for over 4000 h. The improved PL properties are attributable to the fixation of the surface ligand around the NCs in the specific ordered arrays.

Glutathione peroxidase-like functions of 1,2-diselenane-4,5-diol and its amphiphilic derivatives: Switchable catalytic cycles depending on peroxide substrates.

Amphiphilic derivatives of (±)-trans-1,2-diselenane-4,5-diol (DSTox) decorated with long alkyl chains or aromatic substituents via ester linkages were applied as glutathione peroxidase (GPx)-like catalysts. The reduction of H2O2 with the diselenide catalysts was accelerated through a GPx-like catalytic cycle, in which the diselenide (Se-Se) bond was reduced to the diselenolate form ([Se-,Se-]) by coexisting dithiothreitol, and the generated highly active [Se-,Se-] subsequently reduced H2O2 to H2O retrieving the original Se-Se form. In the lipid peroxidation of lecithin/cholesterol liposomes induced by 2,2'-azobis(2-amidinopropane) dihydrochloride (AAPH), on the other hand, the Se-Se form directly reduced lipid peroxide (LOOH) to the corresponding alcohol (LOH), inhibiting the radical chain reaction, to exert the antioxidative effect. Thus, the two GPx-like catalytic cycles can be switched depending on the peroxide substrates. Furthermore, hydrophilic compounds with no or short alkyl groups (C3) showed high antioxidative activities for the catalytic reduction of H2O2, while lipophilic compounds with long alkyl chains (C6-C14) or aromatic substituents were more effective antioxidants against lipid peroxidation. In addition, these compounds showed low cytotoxicity in cultured HeLa cells and exhibited sufficient anti-lipid peroxidative activities, suggesting their potentials as selenium-based antioxidative drugs.