Molecular synthesis with gaseous fragment ions on surfaces

Chemists often treat gaseous fragment ions as esoteric chemical species of interest to only analytical mass spectrometry and gas-phase ion chemistry. However, their potential as building blocks for designing new compounds in the condensed phase is largely unexplored. Developments in preparative mass spectrometry instrumentation have opened up a new research field focused on understanding the chemistry of well-defined gaseous fragment ions on surfaces. In this Review, we highlight the preparative potential of gaseous fragment ions for synthesizing new compounds in the condensed phase. We discuss factors affecting the selectivity of the observed reactivity of fragment ions, examine the effect of charge on reaction mechanisms, and introduce the unexpected reactivity of ions of the same polarity on surfaces in the absence of solvent molecules. These developments hold the potential to transform preparative mass spectrometry into a valuable method for small-scale chemical synthesis in almost all fields of molecular sciences.