A molecular machine is a nanoscale device in which molecules are mechanically interlocked and perform controlled motion when supplied with energy. Sauvage used a copper ion as a template to synthesize catenanes—two interlocked rings—with unprecedented yield. Stoddart exploited charge-transfer attraction to thread a ring onto an axle, creating rotaxanes whose rings shuttle back and forth. Feringa designed a light-driven molecular motor that rotates in a single direction and now exceeds 12 million revolutions per second. These breakthroughs open paths toward molecular computers, targeted drug delivery, and smart materials.

Focusing on mechanical rather than covalent bonding, the laureates constructed topologically entangled molecular assemblies with precise control. Sauvage’s catenane synthesis employed a Cu(I)–phenanthroline template, achieving 42 % yield in interlocking two macrocycles. Stoddart harnessed donor–acceptor interactions to thread a macrocycle onto an axle, engineering bistable rotaxanes whose ring position can be switched by external stimuli. Feringa combined chiral centers with sterically hindered C=C bonds to realize unidirectional rotation via a photo-isomerization / thermal relaxation cycle, ultimately reaching >12 MHz. These dissipative systems function out of equilibrium, echoing biological molecular machines. They have since enabled molecular elevators, artificial muscles, nanocars, and logic elements, providing a versatile platform across nanotechnology, materials science, and chemical biology.

Sauvage exploited π-acceptor phen–Cu(I)–phen complexes to orchestrate π-stacking and coordination forces, forming a dynamic [2]catenane precursor that was fixed via oxidative macrocyclization. Stoddart utilized tetrathiafulvalene / hydroquinone donor–acceptor pairs to template self-assembly of a bistable [2]rotaxane, subsequently end-capping the axle and demonstrating pH-, redox-, and photo-controlled shuttling. Feringa introduced a helically chiral bicyclo[3.3.1]nonane framework; photo-induced E/Z isomerization followed by thermally driven helix inversion biased the system to deliver unidirectional torque. Single-molecule STM/AFM studies verified operation, and incorporation into self-assembled monolayers on conductive surfaces has been reported. From a nonequilibrium thermodynamics viewpoint, dissipation of light or chemical fuel correlates with flip rate/rotational frequency, enabling quantitative models for mechano-chemical energy transduction at the microscale. Future challenges include integrating task-specific work cycles within reaction networks and establishing design principles for ensembles that combine catalysis, information processing, and energy storage.