Thiol modifier effects of diphenyl diselenides: insight from experiment and DFT calculations

A combination of spectroscopic, chromatographic and computational approaches was employed to investigate the reaction of several diselenides of formula (R-PhSe)(2) (R = CH3O, CH3, H, Cl, CF3) with a thiolate nucleophile, leading to the breaking of the selenium-selenium (Se-Se) bond. This process has fundamental importance in biological environments and provides a rationale to analyze the so-called thiol modifier effect of diselenides, which may be exploited in pharmacology and toxicology. Our data suggest that withdrawing substituents favor the reaction, effectively making the reaction energy more negative, but strong electron-withdrawing groups also prompt structural modification on the starting reactant, increasing the reaction barrier. Thus, the nature (electron rich or electron poor) of the diselenides can play an essential role in the reactivity and biological activity of these molecules

Dynamic pigmentary and structural coloration within cephalopod chromatophore organs

Chromatophores in cephalopod skin are known for fast changes in coloration due to light-scattering pigment granules. Here, authors demonstrate structural coloration facilitated by reflectin in sheath cells and offer insights into the interplay between structural and pigmentary coloration elements