10/13/2007

Goodnight Moon, Goodnight Sun, Goodnight Calix[6]arene

If you're into molecular machines (and who isn't?) then you might get a kick out of this recent JACS paper. The rest of you who could care less will at least like their graphical abstract:


Cuuuute! Look at that happy sun! And that content moon! And... what the hell is that red thing? And blue thing with the blue tail? And it's... going.. in... what? Now vigilant CBC readers are probably thinking "oh god, not this shit again. He's probably gonna call it a nanotampon or something, isn't he?" Well, that's where you're wrong. I'm not going to stoop to your pedestrian humor, cause I'm a classy guy. Perish the thought that I would ever sink so low as to use bodily humor to illustrate the diverse and fascinating chemistry of rotaxanes, which is exactly what this system is, and is activated in the presence of light by a photoacid.


Anyway, the nanotampon (...dammit) is a simple monoalkylated 4,4'-bipyridinium, with one basic site. The, um, nano...ah, fuck it. It's a calix[6]arene.[1] Now as it turns out, the protonated bipyridinium forms a nice pseudorotaxane with the calixarene. So the authors decided to use a merocyanine photoacid to turn the rotaxane assembly and disassembly into a process that can be switched on and off with light. Photoacids are simply molecules that, when exposed to light, release a proton. This merocyanine-spiropyran system is a photoacid:


So, upon release of that proton in the presence of light, the bipyridinium is protonated, and the pseudorotaxane is formed. Put it in the dark, and the system slowly (~7 days for full conversion) disassembles. And unlike real tampons, the process is completely reversible.[2]

One can debate the usefulness of molecular machines- I frankly don't see any real use for this thing. But c'mon, cuuuuuuuute graphical abstract, and I think photoacids are awesome. I wish more papers had happy suns.

[1] God I am SO GLAD the authors used the default ChemDraw template for calixarenes here. Seriously.
[2] I deeply apologize for that gross remark.

8 comments:

Chemgeek said...

hee hee... nanotampon

Ψ*Ψ said...

Yeah...that definitely cracked me up.

Das Entropiemonster said...

Calix[6]arene sounds really dirty.

sam said...

merocyanines are really cool. i like 'em. i'm really into photoswitchable right now!

milkshake said...

Merocyanines: In Soviet Union, the bank safes were equipped with a capsule of intensely yellow dye that bursted and stained the content if the safe was opened by force. My former boss with whom I was working on anti-coagulants) told me that he ended up arrested and questioned "after the russian manner" because he was working with merocyanines and his hads were stained yellow - and one day there was a robbery...

Ashutosh said...

Now all we need to do is prevent nano-HIV with nano-condoms. Come up with a model for this and you win the next Nobel.
This kind of lingo seems to have entered the kitchen by the way. Yesterday, in On The Border, I had Pico Chicken and Shrimp...

Uncle Al said...

BIPS so soooo old school. A real man uses a Cooper Blue analogue (pick any ketone or aldehyde)- though that photo-proton thingie is kinda problematic.

taitauwai said...

At first glance, the red thingy looks like a red fire cracker.