Future Applications of Photo-Driven Molecular Machines

The construction and operation of photo-driven molecular machines, capable of performing linear or rotary motion at the molecular scale in response to external light stimuli, continue to be a hot topic in the field of nano-science and nanotechnology. A current big challenge in this field is to make these intriguing molecules perform useful tasks. Besides a discussion of novel means used to control linear and rotary motion in solution phases among such lightresponsive molecular systems, this minireview focuses on selected recent examples of light-driven molecular machines that can perform linear or rotary motion on surfaces and have been harnessed to generate changes in surface properties. This minireview also highlights recent advances on photo-controllable nanovalves based on mesoporous silica nanoparticles. The first example to demonstrate the collective unidirectional rotary motion of an ensemble of molecular motors that can rotate microscale object is highlighted, followed by a brief conclusion and outlook.