The detection of molecules in the interstellar medium relies on the comparison between observational and laboratory data recorded under relevant conditions. In this contribution, the use of cryogenic ion traps to obtain low temperature spectra of gas-phase ions of astrophysical relevance is reviewed. By exploiting the unique properties of these devices, the requisite spectroscopic data that led to the identification of C + 60 as the first carrier of the enigmatic diffuse interstellar bands could be measured. These experiments are discussed, along with electronic transitions of other fullerenes, and recent approaches to synthesize and characterize molecular ions of long-held astrochemical interest.