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Showing posts sorted by date for query pedal molecule. Sort by relevance Show all posts

08 February 2018

Real Pedal Power?

I have to admit that I know nothing about molecular chemistry.  It's one of those areas, like much of physics, that sounds interesting but for which I lack the background, and possibly the aptitude (My math skills are, depending on your point of view, comically or frightfully bad!) to understand.

So when I read this article, all I knew was that scientists somehow managed to synthesize molecules that operate like the pedals of a bicycle. It sounded really cool.


 From what I understand, these molecules can be activated by light to act as "switches", moving from one structural state to another as they move like the pedals around a bottom bracket.  However, they do not perform a full rotation, but move back and forth in arcs around the "axle."

In contrast, other kinds of molecules exhibit large-scale rotation around one bond, and need much more space than the "pedal" molecules need in order to make the "switch".

Why is this important?  Well, "switching" is necessary in order to create the molecular structures necessary in a number of applicatons, from pharmaceuticals to computers.  I would imagine that it is also vital to much "green" technology.  


I once built a wheel that looked like this.  I didn't ride it, though!


As I understand, these molecules change their structure in a way analagous to that of water it becomes ice or vapor.  When water is heated, its vapor needs more space because it expands.  On the other hand, when water cools down to 4 degrees C, it contracts but, unlike other liquids, expands when it freezes. You can see this when a river or lake ices over.) Just as liquid water acts differently from vapor or ice when you try to combine it with other things, whether and how molecules bond depends on their structural state.  So, the necessary molecular structures for a number of things, from pharmaceuticals to plastics, can be created only when the molecules can reach the right state.  And that can only happen when the would-be "switches" are allowed to switch.  

If water in a pipe freezes, it will expand the pipe until it bursts.  On the other hand, if molecules in other environments are so restricted, they just don't move and therefore don't make the necessary "switches." That is the reason why researchers and engineers have been limited in what they can create.

The "pedal" motion, as it turns out, is more compact than other kinds of molecular motion.  This means the atoms that are part of the molecule aren't displaced much, if at all--which,  in turn, means that the molecule doesn't (and doesn't have to) move as much.  This could allow scientists and engineers to create new kinds of structures.

Of course, we as cyclists always knew that the pedaling motion was very economical and efficient--and, when performed even by people of ordinary ability, graceful.  Is it any wonder, then, that so much of today's technology--including that of automobiles and aircraft--came directly or indirectly from bicycles.  Now it looks like even more sophisticated technology will soon owe its debt to our beloved two-wheeled vehicles--in this case, our method of propulsion!