Researchers at the Institute of Organic Chemistry and Biochemistry in Prague have made a breakthrough in the field of molecular engineering. They have developed a light-controlled molecular motor that can reversibly hinder the random rotation of another component within the same molecule. This innovation has the potential to revolutionize the way we approach molecular engineering and could lead to the development of new technologies. The team, led by Jiří Kaleta, built the motor and rotor into a rigid molecular framework and investigated how they interacted. They found that when light is shone on the molecule, the motor changes its configuration, which in turn affects the rotation of the attached rotor. This is a significant finding, as it shows that the motor can control the motion of the rotor without turning it into a continuously driven propeller. The distinction between the two moving components is crucial to this result. The motor and rotor are not directly connected, but rather interact through the space around them. This allows the motor to control the rotation of the rotor without directly driving it. The team's findings have been published in Angewandte Chemie International Edition. The implications of this discovery are significant. It could lead to the development of new technologies that can regulate motion at the molecular level, which could have far-reaching applications in fields such as medicine, materials science, and energy. The ability to control molecular motion could also lead to the creation of new materials with unique properties, such as self-healing materials or materials that can change shape in response to light. While the team has not yet observed continuous four-state operation under the conditions that resolved the slower rotor, their findings demonstrate a control principle that could be developed further. The use of light to control molecular motion is a promising area of research, and this breakthrough could pave the way for new discoveries in the field.