text: *Porphyrins, and phthalocyanines have highly tunable photochemical and electrochemical activity as well as the potential to form complexes.
  *Photochromic and photoisomerizable groups can change their shapes and properties, including binding properties, upon exposure to light.
  *Tetrathiafulvalene (TTF) and quinones have multiple stable oxidation states, and therefore can be used in redox reactions and electrochemistry.
  *Other units, such as benzidine derivatives, viologens, and fullerenes, are useful in supramolecular electrochemical devices.