4 ms·

What's staggering is that small-molecule crystallography is so cheap. A x-ray diffractometer with area detector is maybe 50 kUSD, and after 8 hours you have a d

What's staggering is that small-molecule crystallography is so cheap. A x-ray diffractometer with area detector is maybe 50 kUSD, and after 8 hours you have a dataset, the full hemisphere. It's baffling why anyone would cheat!

gus_massa 4y ago
I guess the hard part is making the real substance and then making nice crystals to put in the device. I think they are just lying about everything. Also, it looks like they are changing the topic each year to follow the current fashion, and they are publishing like 200 papers per year, so $50K is like $250 per paper. My (totally unsupported) guess is that they are charging a few hundred bucks per paper, so using a real diffractometer to make a new unique fake image for each paper would duplicate the price of each paper.
murphyslab 4y ago
Growing good, X-ray quality crystals is more art and luck than science. It's particularly difficult with most proteins and other biomolecules. [0] But even for small molecular compounds, it isn't always easy. I'm not sure about growing high quality crystals of metal-organic frameworks, but they could easily be limited by defects. Some compounds might be too waxy if there are long aliphatic chains involved. Even if you do get decent-looking crystals, they might be twinned. If you are working with air or water sensitive compounds, they need to be handled with extreme care and might degrade before the data collection is complete. Some might also have temperature sensitivity, such that they need to be kept at -20 C to prevent melting or another phase transition. Overall it can be a real make-or-break issue for someone engaged in chemical research. [0] Check out this PDF of a PowerPoint on the topic: https://hamptonresearch.com/uploads/documents/ramc/RAMC2011_Seeding%20Workshop.pdf https://hamptonresearch.com/uploads/documents/ramc/RAMC2011_...
- muaytimbo 4y ago
  Growing high quality crystals of Organometallic compounds is easier than many other disciplines in chemistry, orders of magnitude easier than proteins, as an comparison.
  - COGlory 4y ago
    Depends. A random metallo-organic compound vs a random protein? Yes. But the problem can be further up the chain. Synthesis can be expensive and difficult, and you need a relatively large crystal (at least for X-ray). If you have low symmetry, you need several relatively large crystals all of which need to collect enough data before they die to integrate across the datasets. It typically isn't thought to be as challenging, but it can be.
    - muaytimbo 4y ago
      In my experience it's always been easier both growing and solving organometallic compounds. Borrowing the phase from previously solved structures is trivial for organometallic compounds which simplifies the density modeling while the fact that most organometallic compounds lack the chirality found in every protein generally means they pack into higher symmetry groups facilitating the growth of larger high quality crystals.

gus_massa 4y ago

I guess the hard part is making the real substance and then making nice crystals to put in the device. I think they are just lying about everything. Also, it looks like they are changing the topic each year to follow the current fashion, and they are publishing like 200 papers per year, so $50K is like $250 per paper. My (totally unsupported) guess is that they are charging a few hundred bucks per paper, so using a real diffractometer to make a new unique fake image for each paper would duplicate the price of each paper.

murphyslab 4y ago

Growing good, X-ray quality crystals is more art and luck than science. It's particularly difficult with most proteins and other biomolecules. [0] But even for small molecular compounds, it isn't always easy. I'm not sure about growing high quality crystals of metal-organic frameworks, but they could easily be limited by defects. Some compounds might be too waxy if there are long aliphatic chains involved. Even if you do get decent-looking crystals, they might be twinned. If you are working with air or water sensitive compounds, they need to be handled with extreme care and might degrade before the data collection is complete. Some might also have temperature sensitivity, such that they need to be kept at -20 C to prevent melting or another phase transition. Overall it can be a real make-or-break issue for someone engaged in chemical research. [0] Check out this PDF of a PowerPoint on the topic: https://hamptonresearch.com/uploads/documents/ramc/RAMC2011_Seeding%20Workshop.pdf https://hamptonresearch.com/uploads/documents/ramc/RAMC2011_...

muaytimbo 4y ago
Growing high quality crystals of Organometallic compounds is easier than many other disciplines in chemistry, orders of magnitude easier than proteins, as an comparison.
- COGlory 4y ago
  Depends. A random metallo-organic compound vs a random protein? Yes. But the problem can be further up the chain. Synthesis can be expensive and difficult, and you need a relatively large crystal (at least for X-ray). If you have low symmetry, you need several relatively large crystals all of which need to collect enough data before they die to integrate across the datasets. It typically isn't thought to be as challenging, but it can be.
  - muaytimbo 4y ago
    In my experience it's always been easier both growing and solving organometallic compounds. Borrowing the phase from previously solved structures is trivial for organometallic compounds which simplifies the density modeling while the fact that most organometallic compounds lack the chirality found in every protein generally means they pack into higher symmetry groups facilitating the growth of larger high quality crystals.