Sunday, December 25, 2011

Chemistry Meets Origami Again

As some people may be aware and others not so much, I am a full time chemistry student in university at the moment. I've been interested in chemistry for seemingly forever, and I've made a couple models in the past to try to represent concepts in chemistry. However, for the longest time what I really wanted to fold was an organic chemistry model kit. I'd seen one before somewhere (if you find it, feel free to send me the link) but I thought it would be best if I designed my own. I didn't have the idea on my mind for the past couple of months until, taking organic chemistry my professor suggested we go out and buy model kits to help visualize the molecules we were dealing with. It wasn't until two days before my last final exam of the semester (which happened to be my organic chemistry exam) that I came up with an idea that worked.

My main problem when trying to fold a model kit was the tetrahedral shape. I could see how it would be possible to fold a unit from a single square, but not without wasting a lot of paper. Finally, for some reason I had the idea to fold two identical units that could fit together to make the tetrahedron. I tried folding the elbow section so that the slits on the two units would fit together, but that didn't have any way of locking. After playing with that idea, I decided to try something else: using two different units. At first, one unit was just a 90° elbow using reverse folds, and the other flat piece was simply slid into the elbow. That, like before, fell apart easily; however, by changing the elbow to have alternating 22.5° angles, the second unit locked in place nicely. I left the model like that until a couple days ago, when I realized that one of the units was too floppy. I added a sink fold to unit 1 and a crimp to unit 2 so that both units would hold their respective angles equally. The result is a couple of really simple units which can make just about any molecule, such as ethanol:

Facebook Logo, Ryan MacDonell

Or benzene:

Facebook Logo, Ryan MacDonell

The diagrams show how to make and assemble the two tetrahedral units, as well as the hydrogen unit. The tetrahedral angles should be 109.5°, but the diagrams use 90°. This is on purpose because the angles tend to unbend a little. Note that a lot more can be improvised such as double bonds and simply atoms like oxygen and sulfur. I haven't quite figured out how triple bonds or sp3 centres with a lone pair (such as nitrogen) will work, but I'm pretty sure they're both possible.

Click Here for Diagrams.

Normally I wouldn't draw diagrams, especially not for something so simple. For some reason I hope that the model might be useful for someone who, like me, never had a model kit. Unfortunately with things like closed sinks and crimps involved a non-folder might have a bit of trouble, although I would love to be proved wrong.


origami madness said...

This is probably what you're thinking of. Shuzo Fujimoto has also done a very nice one, info is in one of his books-- I can dig it up for you if you want.

Yours is so elegant though... Might actually be worth the effort as a study tool :)

Ryan said...

I'm pretty sure thats the one I'd seen before. I'd be curious to see what the units are like in Fujimoto's version, but even a description would suit me.

And thanks, thats the idea. Unfortunately I feel like I can't simplify it enough so that anyone could use it. I hope someone will benefit from it, though.

Dan Best said...

Hi Ryan,

I am interested in using your origami model kit for a piece of cover art to accompany an article in the Journal of Organic Chemistry.

Please get in touch if such a project would be of interest to you.




anoop said...

hi Ryan

your tetrahedra model is the one i am searching for the last month. I have some doubts. can you pls give me your mail id? so that i can ask clearly the doubts.