MurphysLab OP t1_jbqpupt wrote

These molecules help chemists to understand the properties of aromatic molecules. Think of it as a single data point, but the most difficult data point for the experiment; one which no one has ever been able to get before. But that data point answers questions about the nature of several other chemical compounds.


MurphysLab OP t1_jbifznn wrote

/u/BiochemistChef's response is great, so I'll try not to repeat.

Instead, I'll highlight another aspect: A ring containing 6 nitrogen atoms and 6 electrons in pi-orbitals is something which theory has predicted could exist for a long time and which we might make. But while theory is good, reality is always more interesting. Reality often functions as the measuring stick by which we can see if our theories are correct or not. That's the fundamental nature of science.

Consider those physicists who keep on proving Einstein right again and again: They're checking to see if reality looks the same as our theoretical understanding.

Another aspect of why this was published in a prominent chemistry journal (and why I'm rather enthused about the result) is that benzene has very interesting chemistry which is the result of the special arrangement of electrons which it possesses. It's the foundation of huge swaths of chemistry. And so chemists have seen how we might modify it so it's not just 6 carbon atoms in a ring.

Chemists wonder "What happens if we start swapping out some of the 6 carbon atoms in a benzene ring for different atoms?" Those molecules are termed heterocyclic compounds.

What happens if you swap 1 carbon atom with a nitrogen atom? Pyridine is just that and it's a motif which appears frequently. The nitrogen allows chemists to use it as a ligand for metal atoms.

What if we replace 2 carbon atoms with nitrogen atoms? We've done that. It give you pyrimidine, pyrazine, and pyridazine, each with different chemical properties.

You'll note that the series doesn't stop with just 1 or 2 nitrogen atoms substituted. We can imagine a complete series:

  • 6-membered rings with zero nitrogen atoms: benzine
  • 6-membered rings with one nitrogen atom: pyridine
  • 6-membered rings with two nitrogen atoms: diazines
  • 6-membered rings with three nitrogen atoms: triazines
  • 6-membered rings with four nitrogen atoms: tetrazines
  • 6-membered rings with five nitrogen atoms: pentazine (still only hypothetical)
  • 6-membered rings with six nitrogen atoms: hexazine

Using series of molecules like that, we can better understand why they have the properties that we observe and how we might plan to change the properties of other similar heterocyclic molecules.

I'd add that many of those N-heterocycle motifs turn up in really useful molecules. For a munch of my PhD, I worked with plastics containing polyvinylpyridine to make cool nano patterns.

Those nitrogen containing aromatic molecules also turn up in pharmaceuticals:

Many of those need the nitrogen(s) in the ring for efficacy, so it's also worth exploring new synthetic methods for making nitrogen heterocycles. They aren't typically using lasers and diamond anvil cells, but the future might hold some surprises.


MurphysLab OP t1_jbg6r9s wrote

Previously, aromatic hexazine, [N₆]⁴⁻, was a hypothetical chemical structure which would follows Hückel rule for aromaticity: a planar ring molecule will have aromatic properties if it has 4n + 2 π electrons, where n is a non-negative integer.

Compounds with a high proportion of nitrogen tend to exhibit explosive properties, given the relative stability of molecular nitrogen (N₂ gas) (see: The Explosive Chemistry of Nitrogen: A Fascinating Journey From 9th Century to the Present), making their synthesis both difficult and risky, hence why a synthesis for [N₆]⁴⁻ has been so long in coming and why it would need to be performed at high pressure.

Prior to this, all-nitrogen aromaticity, had restricted to the [N₅]⁻ pentazolate anion. A similar synthesis reported in 2022 produced the anti-aromatic [N₆]²⁻, starting from potassium azide (KN₃).

The results are published in Nature Chemistry:

Dominique Laniel et al.: Aromatic hexazine [N₆]⁴⁻ anion featured in complex structure of the high-pressure potassium nitrogen compound K₉N₅₆. Nature Chemistry (2023). DOI:


MurphysLab t1_j2b6byu wrote

The PsyPost article doesn't mention and I don't have access to the journal, so perhaps someone can tell me: Does the study ask whether there's a difference between owning a cat, dog, bird, or other kind of pet? Having a dog would also lead to more walking compared to owning a cat, so I'm curious if that's playing a mediating role in protecting cognitive health.