Chemical bath deposited films of CdSe nanocrystals (<4 nm) are shown to exhibit time-dependent spectralred shifts, caused by increasing overlap of the electron wave functions in adjacent nanocrystals. Treatment ofthese “aggregated” films with aqueous KCN solution results in repulsion of the wave functions due to thestrongly adsorbed negatively charged cyanide and thus electronic decoupling of the physically connectednanocrystals. The previously reported band gap increase due to cyanide adsorption on nominally uncouplednanocrystals is also described here in more detail.