[Archer]

Does anyone have any experience of using Single Crystal X-Ray diffraction?

I am interested in the aquisition time for some of the more modern instruments when looking at small molecules <50 non-hydrogen atoms (not including data processing using SHELXL or similar)

My colleagues any I are looking into collaborating on an instrument purchase (although I doubt this will happen but we will put in a business case nonetheless and hope) and we wanted to know what the throughput is roughly if the instrument is used at full capacity.

Any comments are, as always, greatly appreciated.

[AWK]

This hardly depend on quality of crystal, its size and purpose for measurements - from a few hours to a few days.

[408]

And with a large crystal, even a few minutes is enough to see the pattern of non-hydrogen atoms sometimes.

[Archer]

I've seen some manufacturers boasting 20 minutes with crystals 0.12 x 0.13 x 0.14 mm

Apparently the refinement software is pretty good these days too.

[discodermolide]

you don't need a single crystal, absorbent material, and you can get x-rays of compounds as they come off a GC.
According to a recent Nature paper. (which I have).

[curiouscat]

Out of curiosity what will you use this for? Not my area but just being nosy.

[Archer]

you don't need a single crystal, absorbent material, and you can get x-rays of compounds as they come off a GC.
According to a recent Nature paper. (which I have).

Nice, what is the title?

Mind you I can remember a lot of people getting excited about LC-NMR but I don't think this really was as good as its price tag suggested.

[Archer]

Out of curiosity what will you use this for? Not my area but just being nosy.

We would use it to aid in the identification of small molecules which require a special licence to posess. Very few establishments have both the instrument and a licence so those that have charge a huge admin fee on top of their normal charge, which is usually charged by the non-hydrogen atom.

[DrCMS]

Do you really need the crystal structure to confirm illicit drug possession is not NMR and MS enough?

[discodermolide]

you don't need a single crystal, absorbent material, and you can get x-rays of compounds as they come off a GC.
According to a recent Nature paper. (which I have).

Nice, what is the title?

Mind you I can remember a lot of people getting excited about LC-NMR but I don't think this really was as good as its price tag suggested.

X-ray analysis on the nanogram to microgram scale using porous complexes
Yasuhide Inokuma1, Shota Yoshioka1, Junko Ariyoshi1, Tatsuhiko Arai1, Yuki Hitora2, Kentaro Takada2, Shigeki Matsunaga2, Kari Rissanen3 & Makoto Fujita1
PM me with an e-mail, it's a very good paper. probably ideal for your application

[curiouscat]

Do you really need the crystal structure to confirm illicit drug possession is not NMR and MS enough?

Those were exactly my thoughts too.

I always thought of these single crystal instruments as R&D and never as a field analytical technique.

My preconceptions are challenged.

[Archer]

Do you really need the crystal structure to confirm illicit drug possession is not NMR and MS enough?

Unfortunately this is not always enough. The issue is generic legislation in the UK.

Take this exerpt latest SI from the Misuse of Drugs Act 1971 for example

Any compound structurally derived from 3–(1–naphthoyl)indole, 3-(2-naphthoyl)indole, 1H–indol–3–yl–(1–naphthyl)methane or 1H-indol-3-yl-(2-naphthyl)methane by substitution at the nitrogen atom of the indole ring by alkyl, haloalkyl, alkenyl, cyanoalkyl, hydroxyalkyl, cycloalkylmethyl, cycloalkylethyl, (N-methylpiperidin-2-yl)methyl or 2–(4–morpholinyl)ethyl, whether or not further substituted in the indole ring to any extent and whether or not substituted in the naphthyl ring to any extent.

This covers an infinite number of substances, many of which cannot easily be distinguised by spectroscopic techniques. But in order for a prosecution one has to prove beyond reasonable doubt that the substance falls into this generic definition of a drug.

whether or not further substituted in the indole ring to any extent and whether or not substituted in the naphthyl ring to any extent

This is the real issue because if there is, for example, a fluorine and a trifluoromethyl are attached to the naphthyl ring (which can be attached to the main skeleton at either the 1- or the 2- position) it can be very difficult to assign where on the ring this is, without a reference material often these are not available due to the infinite number of possible analogues.

It is possible with 2D NMR techniques if the aromatic protons are well resolved and the splitting patterns can be identified but one still needs a relatively pure sample for NMR and it is a lot simpler to prove using SC-XRD.

This is not really a field technique as such but it can be a helpful tool in identification which saves a great deal of time and as such can be worth the money.

[curiouscat]

Interesting.

When you spread cost of that instrument over the number of prosecutions that need this how much does the cost of prosecution come to, I wonder!

[Archer]

Interesting.

When you spread cost of that instrument over the number of prosecutions that need this how much does the cost of prosecution come to, I wonder!

For us It's more about harm reduction rather than criminal prosecution and unfortunately these cases are on the increase.

Plus the instrument can be used for academic purposes during the down time.

[clarkstill]

I saw him speak in Bristol and it's pretty spectacular, although this corrigendum is slightly embarrassing:

http://www.nature.com/nature/journal/v501/n7466/full/nature12527.html

you don't need a single crystal, absorbent material, and you can get x-rays of compounds as they come off a GC.
According to a recent Nature paper. (which I have).

Nice, what is the title?

Mind you I can remember a lot of people getting excited about LC-NMR but I don't think this really was as good as its price tag suggested.

X-ray analysis on the nanogram to microgram scale using porous complexes
Yasuhide Inokuma1, Shota Yoshioka1, Junko Ariyoshi1, Tatsuhiko Arai1, Yuki Hitora2, Kentaro Takada2, Shigeki Matsunaga2, Kari Rissanen3 & Makoto Fujita1
PM me with an e-mail, it's a very good paper. probably ideal for your application