Separations using Organic Cages Adam Kewley Supervisor: Prof. A. - - PowerPoint PPT Presentation

Separations using Organic Cages

Adam Kewley Supervisor: Prof. A. Cooper

Overview

• Why separation science
• Cage compounds
• Selective adsorption into a cage
• Analytical separations using a cage

Why Separation Science?

• The products we synthesize aren’t getting any simpler
• Neither are our requirements. We still want robust

analysis and pure products

• Separations are a core solution for these requirements.

Industrial separations are a multibillion pound industry.

• Specialist solutions are very desirable. Especially in

industry, a bespoke solution that works very well for a small group of compounds is desirable My focus is on exploiting a materials properties to perform specialist separations

This Presentation Focuses on Cage 3 (CC3)

• A soluble porous material
• Made by self-assembly via imine condensation
• Easy to make in the lab in high purity
• Chiral precursor leads to chiral CC3-R
• Well studied, good foundation on which we can rationalize its behaviour

And a Lot of Chromatography

2) Separation 1) Injection (t=0)

Mixture Stationary Phase

t 3) Detection

Measuring Selectivity

1) Add Host Control With CC3 2) Activate 3) Add Guest 4) Mix 5) Measure 6) Compare

Example Chromatogram

9 10 11 12 13 Intensity Guest Mixture Guest Mixture + CC3-R Retention Time / min.

Computational Modelling

• Computational modelling was used to help understand why we
• bserve selectivity (credit for the modelling goes to Linjiang Chen)
• It shows that a hydrogen bond exists between CC3-R and (S)-1-

phenylethanol (1-PE). It doesn’t exist for the CC3-R & (R)-1-PE pair.

Bringing it All Together

• Competitive mechanism
• Adsorption measurements (left) align well with models (right)
• A reversible process that doesn’t change or consume CC3

0.5 1.0 1.5 2.0

• 30
• 15

15 30

CC3-R rac-CC3 CC3-S eeS (%) Guest : Host (molar equiv.)

a b

1 2 3 4 5

• 30
• 15

15 30

rac-CC3 CC3-S

eeS (%) Simulation

CC3-R

Linjiang Chen et. al., Nature Materials, submission accepted.

Join the Dots

• Components of a mixture will compete

to adsorb onto CC3 Chromatographic separations work when components of have differing affinities for a stationary phase

• The adsorption is reversible and

involves no chemical or physical change A good column doesn’t change, chemically or physically, when separating mixtures

Make a Column Containing CC3

Take advantage of organic cages solubility: a) Cast a film of CC3-R inside a capillary column Or b) Precipitate rac-CC3 in a controlled manner to give us nanoparticles to fill inside a capillary column

Separating Xylenes

5

Retention Time / min. Intensity rac-CC3 Column Blank Column Elute Together

All Isomers of Hexane

9 rac-CC3 NPs SP-2100 Control Intensity Blank Control Elute Together Retention Time / min.

Credit to Tom Hasell for capturing the SEM images.

Chiral Separations

12

S Retention Time / min. Intensity R CC3-R Column Blank Column R & S Together

Summary

• Developed an easy method for

measuring host-guest selectivity

• Tried to understand the mechanism

and factors that affect selectivity

• Used that information to produce a

working GC columns containing CC3

• The columns were able to perform

some very difficult separations

Outlook

• While separations on CC3 are great

there is a selection of other cage compounds available which may be better at some separations

• A literature method was used to make the CC3 coated
• columns. A commercial-grade production method

would produce higher quality columns capable of even more difficult separations

Acknowledgements