Molecular switches for electron and energy transfer processes based on metal complexes

Molecular switches based on metal complexes, in which electron and/or energy transfer processes are switched on and off or significantly modulated by externally applied stimuli, such as electrons (redox reactions), light, and chemical substances (protons, ions, and molecules), are reviewed. Also described are single-molecule transistors, in which conductance through a single metal complex is modulated by applied gate voltages.