Bis(,-diethyl-4-methyl-4-piperazine-1-carboxamide) tetra-kis-(iso-thio-cyanato-κ)-cobalt(II), a model compound for the blue color developed in the Scott test.

The complex, bis-(,-diethyl-4-methyl-4-piperazine-1-carboxamide) tetra-kis(iso-thio-cyanato-κ)cobalt(II) (,-diethyl-4-methyl-4-piperazine-1-carboxamide = di-ethyl-carbamazine), (CHNO)[Co(NCS)], is presented. This com-plex is a blue precipitate, insoluble in water but soluble in organic solvents, that is formed from the reaction of diethylcarbamazine citrate, a protonated tertiary amine, with cobalt(II) and thio-cyanate. This reaction, in the form of the Scott test, is a common presumptive test for cocaine hydro-chloride.

Origin of the Size-Dependent Stokes Shift in CsPbBr Perovskite Nanocrystals.

The origin of the size-dependent Stokes shift in CsPbBr nanocrystals (NCs) is explained for the first time. Stokes shifts range from 82 to 20 meV for NCs with effective edge lengths varying from ∼4 to 13 nm. We show that the Stokes shift is intrinsic to the NC electronic structure and does not arise from extrinsic effects such as residual ensemble size distributions, impurities, or solvent-related effects.