13
$\begingroup$

In the particle physics, there are non mirror-symmetric reactions.

In the organic chemistry, particularly in complex proteins, there are reactions producing only a single chirality of molecules.

But what is in the intermediate regime? Does any inorganic chemical reaction exist with an asymmetric chirality behavior?

I suspect, maybe it would be possible with highly asymmetric electron clouds, probably with a significant EM octopole moment.

Improve this question
$\endgroup$
20
  • $\begingroup$ Note: as generally in the case of the "does ... exist" questions, giving a "no" answer is harder, but it is still possible. $\endgroup$
    – peterh
    Commented Oct 18, 2016 at 19:34
  • 7
    $\begingroup$ There are no reactions producing only a single chirality, unless they start from a single chirality. Besides, there are some reactions producing a slight excess of one enantiomer over the other as a result of some asymmetric physical influence (circularly polarized light, etc). Inorganics is no different from organics in this regard. $\endgroup$
    – Ivan Neretin
    Commented Oct 18, 2016 at 20:01
  • 1
    $\begingroup$ Yes, that's right; the resulting enantiomer would be determined by pure chance, hence if you run the experiment many times, it would turn out "right" and "left" about equally often. Of course you might use a seed crystal, and probably with great results; that's the mentioned "chirality from beyond". $\endgroup$
    – Ivan Neretin
    Commented Oct 18, 2016 at 21:26
  • 5
    $\begingroup$ There are plenty of compounds that on crystallization from a racemic mixture, provide two sets of distinct crystals, with each crystal type being nearly enantiomerically pure. Of course, there are equal amounts of both crystal types, but I think even a hypothetical non-chiral observer could sort such macroscopic crystals into two separate bins, a la Pasteur and tartaric acid. $\endgroup$
    – Curt F.
    Commented Oct 18, 2016 at 23:07
  • 2
    $\begingroup$ Maybe the reaction rates between two chiral compounds could also differ if they differ also in their relative chirality. If there is compound1 and compund2, both chiral, then the reaction rate of L-compound1+L-compound2 is the same as R-compound1+R-compound2. But L-compound1+R-compund2 may have a different rate (or even different reactions). $\endgroup$
    – peterh
    Commented Sep 20, 2017 at 18:33

3 Answers 3

Reset to default
3
$\begingroup$

A crystalline form of silicon dioxide known as α-quartz is optically active and can spontaneously crystallize in one of the two optically active form. However, which one of the two you get is defined purely by chance.

This, however, is different from "asymmetry" in particle physics, see here for details.

Improve this answer
$\endgroup$
1
$\begingroup$

Per a source (see http://che.sjtu.edu.cn/EN/Research/tiao_mu/2014/7/31_Construction_and_Mechanism_Research_of_Chiral-Mesoscopic_Inorganic_Materials.html) that appears to directly address the organic/inorganic divide to quote:

"(3) Formation mechanism of chiral inorganic materials

Electronic transition-based optical activity (ETOA) is ubiquitous in organic materials. However, chiral inorganic materials exhibiting optical activity at their characteristic absorption bands attributed to electronic transitions are rare. Our group has reported several work in the field as follows. All of them, including of TiO2 nanotubes, CuO nanoflowers, chiral carbonaceous nanotubes, N-doped chiral carbon nanotubes et al exhibited optical response to circularly polarized light and their antipodal materials showed the mirror-imaged circular dichroism (CD) signals, which could be attributed to the electronic transitions from the lower energy to a higher energy under a dissymmetric electric field."

Improve this answer
$\endgroup$
1
$\begingroup$

Here is a possible answer from inorganic chemistry centered on the $\ce{ClOClO}$ dimer.

Apparently, the $\ce{(ClO)2}$ dimer also exists as $\ce{(OCl)2}$ per the following important reaction leading up to chlorate (problematic from an environmental perspective) formation:

$$\ce{OClOCl + ClOClO -> OClO + Cl2 + OClO}$$

where $\ce{OClO}$ is chlorine dioxide ($\ce{ClO2}$).

Reference

  1. Kinetics and mechanism of chlorate-chloride reaction by Rafaela T. P. Sant'Anna; Cristina M. P. Santos; Guilherme P. Silva; Ricardo J. R. Ferreira; André P. Oliveira; Carlos E. S. Côrtes; Roberto B. Faria, J. Braz. Chem. Soc. vol.23 no.8 São Paulo Aug. 2012 Epub, DOI:10.1590/S0103-50532012005000017 (PDF)
Improve this answer
$\endgroup$
2
  • 1
    $\begingroup$ Ok, but it seems to me only an isomer. $(ClO)_2$ doesn't even seem to me like a chiral compound. $\endgroup$
    – peterh
    Commented Oct 2, 2018 at 14:52
  • $\begingroup$ More research suggests a characteristic property associated with chiral compounds being a response to "circularly polarized light (CPL) " (see che.sjtu.edu.cn/EN/Research/tiao_mu/2014/7/… ). The example in that reference uses amino acid doped CuO nano particles. I believe with that criteria, the list of pure inorganic compounds is limited and includes some esoteric complexes. $\endgroup$
    – AJKOER
    Commented Oct 3, 2018 at 0:24

Not the answer you're looking for? Browse other questions tagged or ask your own question.