I'm wondering if its possible to design a molecule that re-arrange on an electromagnetic (non-visible and radio) signal, and revert back to original structure when signal stops.
Two problems with this.
Firstly you're talking about wavelengths orders of magnitude larger than typical molecules and even whole biological cells.
Secondly at these lower frequencies you are near or below the peak freq. for thermal spectrum at conventional temperatures so unless the molecule is cooled down near single digit Kelvin temperatures, the background thermal fluctuations will randomize any arrangements you're considering.
Likely what is possible has been evolved in nature. (... pause for google searches...)
Consider the temperature sensitive sensory components of many organisms. Your sense of tactile warmth and more selectively a pit viper's heat "vision" must involve protein reconfigurations at the sensor cells. However this is not a direct effect but rather the infrared produces heat which is sensed. [See:http://www.nature.com/nature/journal/v464/n7291/abs/nature08943.html" ]
Phillip S. Callahan suggested moths may detect pheromones from their infrared "colors" but this has pretty much been discounted by the very argument I gave with regard to thermal equilibrium issues. [see: http://www.jstor.org/pss/76364"]