With time, the sense of machine changed to denote molecular systems whose controlled movement can be used to perform work, while systems that cannot do so became distinguished as switches. In the present context and historically speaking, the term machine was used to signify molecular systems whose bond movement (e.g., conformational, configurational, translational, or circumrotational movement) could be externally controlled using a stimulus. A machine, based on the Cambridge dictionary, is “a piece of equipment with several moving parts that uses power (13) to do a particular type of work”. I believe it crucial to try and define, from the outset, precisely what makes a system an artificial molecular machine. For more in-depth analysis of recent advances and examples in the field, I will refer the reader to numerous excellent reviews (4−11) that have appeared recently. Because of space limitations, I will only use select examples chosen to convey my line of argument.
It is informed and inspired by my group’s research (12) and input from others in the field. This outlook is my personal view of where the field is going and what challenges need to be addressed before we get there. (7−11) Pushing things further will require a multidisciplinary approach and the implementation of ideas, concepts, and insights from other fields-biological machines after all did not develop only through chemistry. (4−6) This transformation is the goal that has been, and is, fueling practitioners in the field, and stimulating the progress, development, and inroads that were made of late. The prize when and if-as we do not have the time scale that was available for biology-the end of the tunnel is reached will be revolutionary, reconfiguring every aspect of life and heralding a nanotechnological revolution.
#Molecule on metal surface crystal maker free
We have merely scratched the surface, and much more needs to be achieved before we reach the level of competence/sophistication required to overcome the obstacles in our paths toward engineering useful artificial machines, i.e., molecular systems that transduce or interconvert nonequilibrium free energy without dissipating it (solely) as heat. For this goal to be attained-based on biological examples-alignment, order, directionality, tracks, signaling, communication, compartmentalization, amplification, fuel, regeneration, replication, waste management, temporal and spatial control, and feedback loops (the list goes on and on) are required.
(3) What seems evident to me is that a well-orchestrated symphony of molecular interactions is required to translate molecular-level motion, which is usually induced on the sub-nanometer level into effects that can be measured and used on the micro and macro levels. (1,2) As to how we might attain the same level of exquisite control over molecular motion and function such that they could be harnessed in performing useful work, now that is the real question/challenge. The blueprint of what can be accomplished with artificial molecular switches and machines is already available to us, thanks to biology.