  The understanding of molecular structure and function is at the very heart of
the chemical and molecular sciences. Experiments that allow for the creation of
structurally pure samples and the investigation of their molecular dynamics and
chemical function have developed tremendously over the last few decades,
although "there's plenty of room at the bottom" for better control as well as
further applications.
  Here, we describe the use of inhomogeneous electric fields for the
manipulation of neutral molecules in the gas-phase, \ie, for the separation of
complex molecules according to size, structural isomer, and quantum state. For
these complex molecules, all quantum states are strong-field seeking, requiring
dynamic fields for their confinement. Current applications of these controlled
samples are summarised and interesting future applications discussed.
