Polymorphic properties of DMT

[drpotato]

to throw a wrench in your nice little brain thought, consider that substances that polymerize also co-polymerize with other polymerizeable substances with the same core group (triptamine) where the difference is only functional groups (methyls, ethyls, propyls, etc). for example, different compositions of polystyrene are made by adding other substituted styrenes and carefully making sure the polymerized chains themselves, now includes a few odd vinyl, chloro or methylstyrenes, rather than just having pure polymethylstyrene, polychlorostyrene or just polyvinylstyrene dissolved amongst the otherwise pure chains of polymerized styrene.
no DMT is pure, and the impurities may well augment the properties of the polymers as well, when polymerization occurs, this also means that if DMT forms 8-mol poly chains, that a 1:7 molar ratio is all thats needed of a particular compatible alt-triptamine to form an entire 8-mol polymer, a 10% contamination could convert almost the entire batches chemical properties to that of the pure co-poly-octimer rather than DMT or its octimer.

I dont know for a fact that triptamines can copolymerize to incorperate substituted triptamines into their chains, but based on what i know of plastics and other things that do, it would be weird if they also couldnt. it might also explain why DMT seems to take on so many radically different forms even at a reasonable purity, dimers and trimers behave very different to monomers, as one would expect from a totally different chemical, since thats what it is, what you know is DMT forms 4/8 molecule dimers, which in this context is a quadrimer/octimer, but then what of NMT the most common alternate triptamine besides just triptamine itself, is it even limited to 4/8?

Apologies if ive wrongly interchanged the terms polymorph and polymer in my descriptions, the point i wanted to make is just in the relation to other polymerization mechanics that could apply to DMT

 

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what you know is DMT forms 4/8 molecule dimers, which in this context is a quadrimer/octimer, but then what of NMT the most common alternate triptamine besides just triptamine itself, is it even limited to 4/8?

I think you're misunderstanding a bit. Crystals and polymers are both repeating patterns of molecules. I don't know much about polymers at all but from what I'm researching about crystals, their macro shape is dictated by the shape of the smallest building block. Molecules have to assemble into these building blocks to fit into the macro structure. DMT can also precipitate amorphously apparently, where molecules may get bonded together in a separate way from the building block crystal path.

The first paper Falkenberg published in 1968 only mentions DMT having 4 molecules in its unit cell (the building block). He found 5-OH-DMT and 5-MeO-DMT have 8 molecules in their unit cell. He notes that they are dimers according to that.



Four years later in 1972 he published again, and this time for DMT he cites two crystal modifications (polymorphs); one with four molecules in the unit cell and the other with eight. He doesn't directly call it a dimer, but that seems to be what he's suggesting, based on how he interpreted 5-OH and 5-MeO.



It might be a bit of a stretch to call the unit cells quadrimers and octimers. But I guess the unit cell would be the first moment you could call it a particle / nucleus / seed. So it's a bit ambiguous whether 4 monomers linking up is a 4-monomer unit cell or a quadrimer block. Aren't polymers bonded covalently? And crystals are bonded a different way? I guess the Z=8 dimer would be a mix of both?

My interpretation is DMT likes to block up in 4's, and apparently if the crystal fuel is dimers then it assembles very similarly, except with 8 in the block. I have no idea if it could get more complex than that with trimers (Z=12) or bigger oligomers, or with parasitic impurities like oxides or NMT.



Z=8 Prisms with Melting point 65.5 C, about the same as what I have with my prismatic yellow gems. I guess I might have dimer crystals.

In the 1968 paper Falkenberg notes that Z=4 polymorph is acicular. This seems to be true when people have gotten "diamonds" there are no acicular formations, which is the more common fanned-out swords.

 

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To clarify: the 'unit cell' is simply the minimum number of (in this case)* molecules required to define the crystalline structure [as interpreted from the x-ray diffraction pattern].

*In other cases, it may be atoms, ions, and/or molecular ions, as well as certain polymeric chains.

 

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@Transform. Thanks, what do you think about the rest of my assumptions? I haven't seen anyone translate these studies in layman's terms, so I'm not very confident on anything. If you want to break them down any further it would be super helpful.

 

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@Transform. Thanks, what do you think about the rest of my assumptions? I haven't seen anyone translate these studies in layman's terms, so I'm not very confident on anything. If you want to break them down any further it would be super helpful.

I'll have to have more of a think about it - I'm not really a crystallographer, for one thing!

 

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(from another thread):

Yes. The longer the contact time with base, the more likely polymerisation becomes.

Mini A/B will sort that out.

Why is that?

Likely from slight deprotonation at the pyrrole (indole) nitrogen. The resulting negatively charged heterocycle becomes more susceptible to oxidation by electron acceptors such as atmospheric oxygen, since it gives up its negative charge more readily than the neutral molecule. I would hypothesise that these resulting radicals begin to initiate polymerisation. The protonation equilibrium lies strongly on the side of indole, which gives a fair bit of leeway.

I can usually only half understand your replies, which gives me homework I'm glad I'm sticking with this though because going back to read what you've said starts to make more sense.
What do you mean by slight deprotonation? Do you mean in the grand scheme of the molecule just one hydrogen leaving is slight? Could DMT be more deprotonated than just at the pyrrole nitrogen?
The paper is describing a product of deprotonation too, isn't it?

Relatively strong N-H...N hydrogen bonds join A-molecules (2.92 A,) and B-molecules (2.89/%,) separately in two different helically fashioned hydrogen-bonding systems around screw axes.

So DMT normally has a hydrogen attached to the pyrrole nitrogen, but if it gets deprotonated (which means lose the hydrogen right?) then it wants to bond with another DMT molecule's pyrrole N-H and form a dimer? That is probably a stupid question but I don't have any other way to check my understanding. We need a DMT molecular chemistry 101 course lol, with quizzes. I'd pay a tuition.

What can we take away from that though? OH- ions are the foundation of freebasing right, it seems unavoidable that some of the DMT molecules could deprotonate in the process? I guess that's why we should limit duration of contact with base... But I don't really understand why the hydrogen, that specific hydrogen, is getting stripped, and what influences the reaction besides time?

This is going on a bit of a tangent but I'm also fuzzy on what oxidation is exactly. I thought it just meant N-Oxide, which after so much reading I'm still confused whether that is real or not? But apparently deprotonation = oxidation? dimerization = oxidation?

The protonation equilibrium lies strongly on the side of indole, which gives a fair bit of leeway.

Why? This must be the key to crystallizing prism vs acicular polymorphs. Lower MP acicular forms seems to be what people get 95% of the time, which aligns with what you say about the equilibrium. But then there's the deprotonated dimer form... It kind of makes sense that the concentrated freebase oil layer that people get at the top of the basic solution would be more likely to dimerize. But from a chemical perspective what's changing the equilibrium so deprotonation occurs and enables dimerization?

Is there any evidence of more than dimers? Tell me about the hypothetical 72 C MP polymorph?

 

[Transform]

What do you mean by slight deprotonation? Do you mean in the grand scheme of the molecule just one hydrogen leaving is slight? Could DMT be more deprotonated than just at the pyrrole nitrogen?

We're talking about bulk statistical properties of a huge number of molecules - remember, the Dalton constant is 6.022×1023 mol-1. That's the number of molecules in 188 or so grams of DMT, for example. Deprotonation of indoles under aqueous conditions is vanishingly unlikely (complete deprotonation of indole* - i.e. each indole molecule has lost its N-proton - requires a stupidly powerful base, like butyl lithium or sodium hydride, which remove the protons by covalently bonding them into a gaseous molecule which effectively leaves the scene entirely). However, using the pKa for indole as a rough guide - 16.2 to 21.0, depending on the solvent - along with the similar value - 16.6 - for skatole, we can see that the dissocation product, Ka, being [H+]×[Ind-] is equal to about log10-116.5, so the actual proportion of dissociated molecules will be the square root of that. We also need to remember that this is a concentration-based phenomenon, meaning that in a crystal or oil, being the most concentrated form of the substance, the relative degree of ionisation will be negligible. {And note that the square brackets are a shorthand convention for the concentration of a species}

[* "complete deprotonation" does not mean that every possible proton gets removed from the molecule - this is terminology regarding a bulk phenomenon. Similarly, "partial deprotonation" refers to only a proportion of the molecules being singly deprotonated, and it's essentially always the most easily removed proton that gets removed.]

More important than whether, or to what degree, this ionisation occurs is how this relates to the charge distribution within the molecule. I'm also feeling that the matter of ionisation of a tryptamine molecule is something of a red herring, although I was using it as a tool to conceptualise an increased tendency to oxidation. When there is an increased negative charge density, it generally follows that it will be more of a likelihood for one of the electrons associated with it to be removed or displaced. This removal or displacement of an electron is what I'm referring to with the term 'oxidation'.

This is going on a bit of a tangent but I'm also fuzzy on what oxidation is exactly. I thought it just meant N-Oxide, which after so much reading I'm still confused whether that is real or not? But apparently deprotonation = oxidation? dimerization = oxidation?

This is a frequent point of confusion for outsiders and novices - the term "oxidation" has been retained for historical reasons. Addition of an oxygen atom is just one very specific case of an oxidation process. Really it's a matter of perspective regarding which electrons go where (and funnily enough, the same thing applies to acids and bases).

The electron in question need not be removed by an oxygen atom (even though atmospheric oxygen would be a likely candidate for the job at times) - the charge transfer of that "more exposed" electron into a π-antibonding orbital of a neighbouring molecule would also count as a type of oxidation, or partial oxidation. This would also be a step in dimerisation/oligomerisation/polymerisation. We're also getting into molecular orbital mechanics, which I tend to find exceedingly difficult to approach rigorously and prefer to visualise in the comfort of my own head.

It gets more nuanced yet, since "the electron" isn't really like a tiny basketball just hanging around in one spot, but it's a kind of vibrating field of probability described by a wavefunction equation, and as previously alluded to, this is one of the points where my brain packed up at university It's taken all day to write this (I've had lots of long breaks, don't worry!) and I'm going to have to leave it at that for now. I hope at least some of it makes sense and maybe even helps

Some of the included terms should help you seek out actual chemical texts written by real professors and not some crazy guy on the internet.

 

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Yea I realize to describe something really well takes a lot of thought and time. Thank you for explaining those mechanics more in depth, it does make more sense now. And I'll follow up with searching the terms too.

Am I reading the paper right when they said:
"Relatively strong N-H...N hydrogen bonds join A-molecules (2.92 Angstrom) and B-molecules (2.89 Angstrom) separately in two different helically fashioned hydrogen-bonding systems around screw axes."

Are they describing a DMT molecule that has lost one proton (molecule-B)? And the deprotonated molecule-B forming a dimer with the pyrrole N-H on a whole DMT molecule (molecule-A)?

If so, wouldn't that polymorph represent 50:50 whole and deprotonated molecules?

 

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Am I reading the paper right when they said:
"Relatively strong N-H...N hydrogen bonds join A-molecules (2.92 Angstrom) and B-molecules (2.89 Angstrom) separately in two different helically fashioned hydrogen-bonding systems around screw axes."

Are they describing a DMT molecule that has lost one proton (molecule B)? And the deprotonated molecule B forming a dimer with the pyrrole N-H on a whole DMT molecule (molecule A)?

I'll have to re-read the Falkenberg paper, but I don't think that's referring to deprotonated molecules - it's just a hydrogen bond to a nitrogen electron lone pair which exists without deprotonation at the 'B' nitrogen atom.