The main objective of COMOTION is to enable novel experiments for the investigation of the intrinsic properties of large molecules, including biological samples like proteins, viruses, and small cells -X-ray free-electron lasers have enabled the observation of near-atomic-resolution structures in diffraction- before-destruction experiments, for instance, of isolated mimiviruses and of proteins from microscopic crystals. The goal to record molecular movies with spatial and temporal atomic-resolution (femtoseconds and picometers) of individual molecules is near. -The investigation of ultrafast, sub-femtosecond electron dynamics in small molecules is providing first results. Its extension to large molecules promises the unraveling of charge migration and energy transport in complex (bio)molecules. -Matter-wave experiments of large molecules, with currently up to some hundred atoms, are testing the limits of quantum mechanics, particle-wave duality, and coherence. These metrology experiments also allow the precise measurement of molecular properties. The principal obstacle for these and similar experiments in molecular sciences is the controlled production of samples of identical molecules in the gas phase. We will develop novel concepts and technologies for the manipulation of complex molecules, ranging from amino acids to proteins, viruses, nano-objects, and small cells: We will implement new methods to inject complex molecules into vacuum, to rapidly cool them, and to manipulate the motion of these cold gas-phase samples using combinations of external electric and electromagnetic fields. These external-field handles enable the spatial separation of molecules according to size, shape, and isomer. The generated controlled samples are ideally suited for the envisioned precision experiments. We will exploit them to record atomic-resolution molecular movies using the European XFEL, as well as to investigate the limits of quantum mechanics using matter-wave interferometry.