Using a synthetic molecular spring device in a system for dynamically controlling a system property, such as momentum, topography, and electronic behavior. System features (a) the synthetic molecular spring device having (i) at least one synthetic molecular assembly each featuring at least one chemical unit including at least one: (1) atom; (2) complexing group complexed to at least one atom; (3) axial ligand reversibly physicochemically paired with at least one complexed atom; and (4) substantially elastic molecular linker; and, (ii) an activating mechanism directed to at least one atom-axial ligand pair; and, (b) a selected unit operatively coupled to synthetic molecular assembly, and exhibiting the system property. Activating mechanism sends an activating signal to atom-axial ligand pairs, for physicochemically modifying atom-axial ligand pairs, thereby activating at least one cycle of spring-type elastic reversible transitions between contracted and expanded linear conformational states of substantially elastic molecular linkers, causing dynamically controllable change in the system property.