What is the most complex molecule we can manufacture without the help of proteins?

This isn't motivated by anything but curiosity about the state of chemical engineering. I realize “complexity” is a loaded term, so I'll defer to the judgment of the respondent: number of molecules, complex arrangement of bonds, or whatever other measure might be appropriate.


closed as too broad by DSVA, Mithoron, Jon Custer, Todd Minehardt, Oscar Lanzi Aug 1 '17 at 15:14

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    $\begingroup$ "Most complex" isn't well-defined. $\endgroup$ – Ivan Neretin Aug 1 '17 at 14:18
  • $\begingroup$ Complex may not be well-defined, but that doesn't mean it isn't a useful term or that, in most cases, we know it when we see it. Big structures that are simple and repetitive wouldn't, I suggest, count. But even small structures with lots of chiral centres might. $\endgroup$ – matt_black Aug 1 '17 at 15:11
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    $\begingroup$ Oh, and a trivial (and possibly ironic) answer might actually be "proteins" since they can occasionally be synthesised without the use of other proteins. Or possibly DNA/RNA which can be built in stages in the lab as a step towards the biological synthesis of non-natural proteins. $\endgroup$ – matt_black Aug 1 '17 at 15:13
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    $\begingroup$ When I was taking freshman chem the book mentioned that a bowling ball is basically a cross-linked polymer network, so if a "complex molecule" is just a lot of atoms covalently bound together I am going bowling. $\endgroup$ – Oscar Lanzi Aug 1 '17 at 15:18
  • $\begingroup$ If we limit the answer to synthesized chemical substances with a single, definite chemical structure, and apply a generally accepted measure of complexity, then this is an answerable question. For synthetic organic chemists, vitamin B-12 used to be Mt. Everest. $\endgroup$ – iad22agp Aug 1 '17 at 18:43

I guess in the field of inorganic chemistry polyoxometalates (POMs) are comparable with proteins in terms of structural complexity. Macroanionic POMs such as Keplerates $\ce{\{Mo132\}}$

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are also capable of further self-assembly in diluted solutions, producing so-called "blackberries" [1] of a size of around $\pu{0.05 .. 0.1 \mu m}$:

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Also, see the post Measure the complexity of a molecule and the corresponding paper [2] of Prof. Lee Cronin, one of the most productive polyoxometalate chemist of current era.

  1. Kistler, M. L.; Bhatt, A.; Liu, G.; Casa, D.; Liu, T. J. Am. Chem. Soc. 2007, 129 (20), 6453–6460. DOI 10.1021/ja0685809.
  2. Marshall, S. M.; Murray, A. R. G.; Cronin, L. arXiv:1705.03460 [q-bio.OT] 2017.

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