MOED and Solvatochromism

It smells just like pyridine, if youve ever smelled it. Its similar to methylamine, but not quite the same

Nile Red

Ive actually made it before and i have a video posted on it

Nile Red

Im not familiar with any of those. What are some examples?

Nile Red

I expected the 4-Methylpyridine to smell like cat piss or something similar to methylamine. Just guesses, though. I have no personal experience with any of it.

Lindy

That could be an interesting idea

Nile Red

It was very tame, smell-wise

Nile Red

Huh did my long reply above the one with the polymer just disappear? Patreon has done it in the past. Too bad as it took a long time to type. In case nobody can see it anymore (I can't) here is the gist of it. Boric acid-> melt until dehydrated and stops bubbling->solidifies, keep heating->melts again. Add fluorescein powder and mix (0.1-0.5%), let cool. Use a sacrificial test tube as the B2O3 glass expands on cooling more than soda glass and the tube will break. The resulting mass is somewhat hygroscopic, keep it in an airtight container as water absorption from the air destroys the phosphorescence. The phosphorescence is blue-green/cyan. Lasts up to 20 seconds after exposure to intense light. I haven't found an alternative material that has the same properties (water-free glass forming material that melts at a low enough temperature to not destroy the fluorescein). Chlorofluorocarbons may be an avenue to explore as a medium for this phenomenon (medium must be as far as I can tell solid and without hydrogen atoms to prevent energy transfer from the triplet state)

Silviu T

FWIW I tried to reproduce this by using a polymer base (IIRC polystyrene) but failed to achieve phosphorescence. I think the key is that no light atoms like H should be anywhere near the fluorescein molecule or energy transfer occurs quickly and breaks the triplet state. That is just a hunch, and I have no formal proof that it's what happens. One avenue to explore would be using a chlorofluorocarbon with no hydrogen; the most obvious candidate (CF2)n is unfortunately opaque though.

Silviu T

That's interesting, Silviu. I never heard of that phenomenon before. I remember that phosphorescence has something to do with the formation of a triplet excited state, but that's all. I wonder why dissolving fluorescein in a glass (or at least one glass, B2O3, would create some sort of triplet state? Have you tried low-melting glasses besides boron oxide? I confess I can't think of any; maybe you can. What color is the phosphorescence, the same as fluorescein in solution? This might be something for Nile Red to play with. It sounds like a pretty uncomplicated experiment, or did you simplify a bit?

mrkhrdr@gmail.com

mrkhrdr@gmail.com can you explain why fluoresceine dissolved in a substance that forms an amorphous solid at cooldown (I used B2O3) becomes phosphorescent (emitted light after excitation is removed persists for several seconds with logarithmic decay) and also the wavelength is blue-shifted compared to fluorescein in water? I have observed this many times but haven't found an adequate explanation for it. Well the wavelength shift maybe, but the prolonged excited state half-life which is several orders of magnitude larger, not so much.

Silviu T

Wow, that's interesting. Looking at Sigma Aldrich's warning list that is some terrifying stuff. More stable but no less evil.

Brian Reddeman

UDMH=unsymmetric dimethylhydrazine. It's hydrazine with 2 methyl groups, both of which are bonded to the same nitrogen. It's an useful component for hypergolic rocket motors in combination with a strong oxidizer. Its main advantage is that it's relatively stable , more so than hydrazine itself.

Silviu T

Any particular bad odor from any of the chemicals? Or did your new fume hood handle it just fine?

Lindy

Yeah, it was kind of long. I just wasn't satisfied with a partial explanation. I didn't learn it in biochem courses or labs either. It's the sort of think you'd probably get in a biophysical chemistry course (physical techniques used for biochemical systems) or a course devoted to proteins by themselves.

mrkhrdr@gmail.com

Could you try make MOED crystal in its A and B form seperatly?. maybe by disolve in acetic acid, when vaperision the acid

Martin Kalum

To be honest I have no idea what UDMH is; As an amateur rocket builder I'd heard about it but never went in the direction of anything evil hypergolic propellants--no point for hobby stuff where solid propellants are perfect. I have to say in a lab your fuels look totally tame. On a recoverable rocket...yeah not so much. Still I've never seen them react in full color (maybe in slow motion?) I can see some interesting cavitation going on.

Brian Reddeman

Long read, but it was definitely very interesting. My degree is in biochem, but I somehow never heard of this before. Maybe because i never really worked in a biochem lab for very long

Nile Red

Solvatochromism also affects the wavelengths at which certain molecules fluoresce. Briefly, molecules absorb photons, which causes electrons to shift from the low-energy, or ground, state to a higher one, the so-called excited state. In fluorescent molecules the excited state decays after a short interval (typically a few tens of nanoseconds) to the ground state. The molecule then emits a new photon as a way of losing the energy difference between ground and excited states, which we observe as the glowing of a sample of a fluorescent compound when it is placed in light of the right range of wavelengths. Enter the solvatochromic effect: When an electron is promoted to its higher energy state, the distribution of the molecule's electrons around its internal bonds changes. Now, the distribution of electrons in a molecule forms a dipole, a vector of electric charge differences (a la partial charges, that is, permanent dipoles). Molecules of a polar solvent also possess electric dipoles, dipoles that point toward the dipoles of their neighboring molecules. Since opposite charges ( full or partial) attract, a dipole-dipole interaction lowers the energies of the molecules that participate in it. If excitation of a fluorescent molecule changes its dipole vector in direction and/or magnitude then the alignment of its dipole-dipole interaction with neighboring solvent molecules changes, the energy of the molecules is not decreased as much. If the lifetime of the fluorescent molecule's excited state is long enough, small solvent molecules have time to realign themselves, bringing the dipole-dipole energy back down. As a result of all this shifting and jiggling, the interaction between an electronic - excited molecule with a polar solvent closes the gap between excited and ground states of the fluorescent molecule. And that means that the energy lost as an emitted photon is smaller - in a polar solvent compared with a less polar one - so the wavelength of the emitted is longer (a red shift). If all this stuff happens in the visible wavelength range you will observe fluorescence at longer wavelengths in water, for example, compared to say, ether. Actually, the effect is small enough that you will need a fluorescence spectrophotomer to see it. But believe me, it's there and it's important for the study of protein structure. Yes, protein structure. To explain that latter thing. A couple of the amino acids in proteins fluoresce in UV energies. The strongest fluorescer is the amino acid called tryptophan (It contains an indole side-chain.) Tryptophan is one of the least polar natural amino acids. The relevant excited state of tryptophan also has a fairly long lifetime - a few tens of nanoseconds - long enough for a water molecule to change its alignment in response to the shift from ground to excited state. Since the interior of typical protein molecules (They're big enough to have a surface exposed to solvent) and a buried interior. The interior is a very weakly polar environment, which is why nature has put tryptophans inside proteins in their native state. OK, stage set: In their usual nonpolar, water excluding environment, tryptophan dipoles in both states form very weak dipole interactions with water molecules on the protein's exterior surface. Suppose that something changes the conformation of a tryptophan-containing protein, something like an unfolding or any change that moves its tryptophans from its non-polar interior toward the surface. That strengthens the interaction between a tryptophan excited state dipole and the water solvent molecules. And that means that the energy split between its excited and ground states decreases and its fluorescence emission red-shifts compared to the protein's native state. As a result, biochemists and biophysicists can use fluorescence solvatochromism to study changes in the conformations of proteins, a standard and very important technique. Phew! Sorry to be so verbose; but I'm working without diagrams here. If you want, look the subject up in a biochemistry/ biophysical chemistry textbook. There are other subtle interactions between tryptophan fluorescence and the optics of other parts of protein molecules that are useful. OK, one last thing. These dipole-dipole interactions I've been talking about are very sensitive to the inter-dipole distance. They decrease in strength with the 6-th power of distance between their centers. For example, a 10% increase in distance decreases the interaction strength by 1/1.1^6 = .56, or 44%! Compare this with a charge-charge interaction: 1/1.1^2 = 1.21, or 21%.

mrkhrdr@gmail.com

You could save half of the total costs by making Iodomethane yourself. In theory it isn´t hard to make (though I have no practical experience with the synthesis...)

From your hypothesis of the colour of your main product, would the crystals formed from the different solvent beakers keep their colour in their crystalline state?

Simon the Delusional

Send some off to Applied Science (Ben Krasnov) I'm sure he would love to try it out.

Simon the Delusional

I would love to see you try to recreate some of the processes of classical alchemy, both Chinese and Western.

Simon the Delusional

Fixed in the updated version :)

Nile Red

Ill fix that in the update!

Nile Red

It's a short/long wave light. I think i visualized this through short wave (i could be wrong though)

Nile Red

I just need some UDMH

Nile Red

I say "so i turned down" but it is hard to understand

Nile Red

interesting idea. Ill just need a transparent pressure chamber

Nile Red

Not sure. I dont think they care too much about it though. I ordered some with it clearly listed on the packaging and they didnt even open or stop it

Nile Red

I wonder what the color would be in a quadrupole solvent, like supercritical CO2. It would probably be like DCM, but I not sure, because the strong quadrupole interaction of CO2 is quite difficult to predict.

Adam Rak

Why is potassium permanganate a class A precursor? I can remember my chemistry kit containing it, for making a 'crystal garden' and catalysing hydrogenperoxide.

4:09 You turn OFF the heating?

Emil Almberg

Also... fun with Analine, Hydrazine and UDMH. Cool :) I keep to safer stuff like N20 and various rubber or sugar :)

Brian Reddeman

I've seen solvatochromism in highschool after class many, many ages ago. Everything he explained made no sense at the time (and he said in in 5 minutes) nor did the term but I remember the colors. I thought it was cool but it wasn't until this video that I ever have seen it happen again. Now the explanation makes sense AND I get to see it all in way better lighting. So cool!

Brian Reddeman

Is that a long wave UV (e.g. "black light")? If so, I wonder what it would do under short wave... I have both and it's remarkable how many things fluoresce under one and not the other, or are dramatically different under each of them.

Michael Aichlmayr

Like the video. When you are adding reactants for the second part of the reaction, you miss the text on the top left for the benzaldehyde (~7:50). Good explanation of solvatochromism which is a not an easy thing to explain on a fairly general level!

So cool! I love how rich those colors are! Tautomerism is hella cool, but also hella complicated. I deal with it on a daily basis. Could you get piperidine by hydrolyzing piperine? @10:41, did you mean tertiary amine? Neither piperidine nor triethylamine are primary amines.

Yeah its unfortunate. To be fair though, Canada isnt crazy strict about it. I have a few chemicals on that list. I just try to avoid it when i can

Nile Red

Sad that so many useful things are on controlled substance lists. I had no idea piperidine was one of them. Stupid PCP! 🤔😕 Nice job knowing what to use in its place!

Michael Aichlmayr

Nice! Love the shout-out to Sigma and their prices! 🤣

Michael Aichlmayr