powder diffraction study of zeolitic imidazolate framework-8
TRANSCRIPT
l Powder Diffraction Study of Zeolitic Imidazolate Framework-8 l March 2015 l Owen Gledhill
Powder Diffraction Study of Zeolitic Imidazolate Framework-8
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A. Petricola, 2008. Ariel view of the ESRF, Available from: http://www.esrf.eu/decouvrir [Accessed on 13/01/2015]
l Powder Diffraction Study of Zeolitic Imidazolate Framework-8 l March 2015 l Owen Gledhill
ESRF – EUROPEAN SYNCHROTRON RADIATION FACILITY
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ESRF, 2008, ESRF brochure [online]. Grenoble: ESRF. Available from:http://www.esrf.fr/about/information-material/brochures [accessed on: 13/01/2015]
Linac
Booster Synchrotron
Storage Ring
l Title of Presentation l Date of Presentation l Author
SYNCHROTRON ANIMATION
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l Powder Diffraction Study of Zeolitic Imidazolate Framework-8 l March 2015 l Owen Gledhill
PXRD – POWDER X-RAY DIFFRACTION
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2θ
Synchrotron radiation (X-
rays) Powder Sample
Detector
I
ID22
• High resolution powder X-ray diffraction beamline.
• Insertion device used is an undulator:
• Also uses a monochromator.
Bragg’s Law
• Path length difference: AB+BC=2dsinθ
• When reflected waves are in phase, AB+BC=nλ
• This gives Braggs Law:
• Commonly shortened to:
ID22, Technical description [online], Grenoble, ESRF. Available from: http://www.esrf.fr/id22/technical-description [accessed on: 21/01/2015] P.Atkins, J. De Paula; Atkins’ Physical Chemistry; OUP, Oxford, Ninth edn., 2010, 701-704
A
B
C
θ
θ
d
l Title of Presentation l Date of Presentation l Author
PLACEMENT OBJECTIVES
• Research current MOF and ZIF chemistry• Synthesise ZIF 8 using a range of methods• Use PXRD as a characterisation technique• Gas adsorption study of ZIF 8
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Unit cell of ZIF 8 showing pore opening comprised of 6-methylimidazole rings
l Powder Diffraction Study of Zeolitic Imidazolate Framework-8 l March 2015 l Owen Gledhill
INTRODUCTION TO MOFS AND ZIFS
• Metal organic frameworks or MOFs are comprised of metal ions or clusters coordinated to organic molecules
• Zeolitic imidazolate frameworks or ZIFs are a subclass of MOFs. They are made of transition metal ions and imidazolate organic linkers.
• ZIFs have structures analogous to those of naturally occurring alluminosilicate zeolites. M-Im-M (where M represents the transition metal ion) angle is similar to that of the 145o Si-O-Si found in zeolites.
• MOFs and ZIFs are highly porous with large surface areas and hence have potential applications in gas storage and catalysis.
• ZIFs have particularly high chemical and thermal stability.
• ZIF 8 is Zn2+ ions with 2-methylimidazole linkers. It takes the form Zn(mIm)2
• ZIF 8 has the space group I3m (no.217)
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l Powder Diffraction Study of Zeolitic Imidazolate Framework-8 l March 2015 l Owen Gledhill
DIFFERENT SYNTHETIC METHODS
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Solvothermal• Reagents are a hydrated metal salt and the
chosen imidazole linker• Organic solvents or alcohols • High yields and near stoichiometric ratio of
ragents• More expensive and more difficult to dispose of
solvents etc…
Hydrothermal• Reagents are a hydrated metal
salt and the chosen imidazole linker
• Water as solvent• More environmentally friendly
option• Requires a large excess of the
linker molecule
Dimethylformamide (DMF) method1:• Zn(NO3)2∙6H2O (14mmol), 2-methylimidazole
(11.7mmol)• Heated in a programmable oven• Precipitate collected by filtrationEthanol/Acetone method2:• Zn(NO3)2•6H2O and 2-methylimidazole (1:8 molar ratio)• Precipitate collected by centrifugation
1. K.S. Park, Z. Ni, A.P. Côté, J.Y. Choi, R. Huang, F.J. Uribe-Romo, H.K. Chae, M. O’Keeffe, O.M. Yaghi; Proceedings of the National Academy of Sciences of the United States of America; 2006; vol. 103 no. 27; 10186-101912. E.L. Bustamante, J.L. Fernández, J.M. Zamaro; Journal of Colloid and Interface Science; 2014; vol. 424; 37-433. K. Kida, M. Okita, K. Fujita, S. Tanaka, Y. Miyake; CrystEngComm; 2013; vol. 15 no. 9; 1794-1801
Aqueous method3:• Used Zn(NO3)2•6H2O (2.5mmol) and 2-
methylimidazole (25mmol)• Heated in a programmable oven• Precipitate collected by filtration
l Powder Diffraction Study of Zeolitic Imidazolate Framework-8 l March 2015 l Owen Gledhill
DIMETHYLFORMAMIDE (DMF) SYNTHESIS
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2θ
I
• λ = 0.496Å• 0.9mm capillary• Indexed using DASH 3.2 to give a cubic unit cell with lattice parameter 17.032Å• Simulated pattern lattice parameter 16.991Å
OG1b diffraction pattern collected on ID22
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0
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50
60
70
80
90
100
10 20 30
Intensity
2-theta
ZIF 8 cubic (Sim) Observed Reflections Empirical with Pawley refinement Simulated ZIF 8 pattern*
*K.S. Park, Z. Ni, A.P. Côté, J.Y. Choi, R. Huang, F.J. Uribe-Romo, H.K. Chae, M. O’Keeffe, O.M. Yaghi; Proceedings of the National Academy of Sciences of the United States of America; 2006; vol. 103 no. 27; 10186-10191
l Powder Diffraction Study of Zeolitic Imidazolate Framework-8 l March 2015 l Owen Gledhill
DMF ANALYSIS – PAWLEY REFINEMENT
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Section of jEdit file with ZnO structural information
2θ
I
Pawley refinement including ZnO structural information
• Impurity is ZnO• Can be accounted for using ZnO .cif file• Pawley refinement run in TOPAS using input file
from jEdit• Unit cell parameter refined to 17.016Å
l Powder Diffraction Study of Zeolitic Imidazolate Framework-8 l March 2015 l Owen Gledhill
DMF ANALYSIS – RIETVELD REFINEMENT
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2-methylimidazole z-matrix
OG1 diffraction pattern with Reitveld refinement ZIF-8 structure
• Rietveld refinement uses structural information to fit the pattern.• All peaks are fit • Sharp peaks show the sample is highly crystalline.
Z matrices• Rigid body• Defines the position of certain
atoms with respect to others• Uses a combination of bond
lengths and angles• In this case, 2-methylimidazole
has been defined using a z-matrix
I
2θ
2-methylimidazole rigid body
l Powder Diffraction Study of Zeolitic Imidazolate Framework-8 l March 2015 l Owen Gledhill
AQUEOUS SYNTHESIS AND ANALYSIS
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I
2θ
• Using the example of OG2. λ = 0.401Å. 1.0mm capillary.• Indexed using DASH 3.2 to give an orthorhombic unit cell with parameters: a= 24.057Å, b= 19.673Å, c=
16.983Å. • Space group P222 was used for Pawley refinement.• It is clearly not ZIF 8.
-10
0
10
20
30
40
50
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10 20 30
Intensity
2-theta
ZIF 8 cubic (Sim) Observed Reflections
Simulated
Empirical
l Powder Diffraction Study of Zeolitic Imidazolate Framework-8 l March 2015 l Owen Gledhill
ETHANOL/ACETONE SYNTHESIS AND ANALYSIS
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2θ2θ
I I
• λ=0.345Å. 1.0mm capillary• Indexed to give lattice
parameter 16.991Å • Pawley and Rietveld
refinement run using space group I4̅3m
• Lattice parameter refined to 16.581Å
Ethanol with Rietveld
Acetone with Rietveld
-10
0
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60
70
80
90
100
10 20 30
Intensity
2-theta
ZIF 8 cubic (Sim) Observed Reflections
Simulated
• λ=0.345Å. 1.0mm capillary
• Indexed to give lattice parameter 17.006Å
• Pawley and Rietveld refinement run using space group I4̅3m
• Lattice parameter refined to 16.619Å
l Powder Diffraction Study of Zeolitic Imidazolate Framework-8 l March 2015 l Owen Gledhill
COMPARISON OF SYNTHETIC METHODS
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Synthetic method DMF Aqueous Ethanol/Acetone
Lattice type Cubic Orthorhombic Cubic
Space group I4̅3m P222 I4̅3m
Lattice parameter(s), (Å)
a=b=c=17.016 a=24.057, b=19.673, c=16.983 a=b=c=16.581 (ethanol)a=b=c=16.619 (acetone)
Diffraction Pattern
2θ
I Ethanol
2θ
I Acetone
I
2θ
I
2θ
l Powder Diffraction Study of Zeolitic Imidazolate Framework-8 l March 2015 l Owen Gledhill
GAS ADSORPTION STUDY/PLANS FOR GAS ADSORPTION STUDY
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• CO2 adsorbed onto sample at various pressures• Analysis will be to try and understand where the molecules lie in the framework• Will look to do further measurements with other gases.
l Powder Diffraction Study of Zeolitic Imidazolate Framework-8 l March 2015 l Owen Gledhill
CONCLUSION SO FAR AND PLANS FOR REST OF THE PLACEMENT
Conclusions• Wide range of synthetic routes• DMF method was most suitable for this study:• Sharp peaks
• Correct lattice parameter
• Uses sensible amounts of reagents
• Gas adsorption• Initial look shows gas was adsorbed into the pores
Future Plans• Further gas adsorption measurements• Repeat measurements
• Further measurements with different gases
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l Powder Diffraction Study of Zeolitic Imidazolate Framework-8 l March 2015 l Owen Gledhill
ACKNOWLEDGEMENTS
• ESRF – European Synchrotron Radiation Facility• In particular:• Christina Drathen
• Andy Fitch
• All the staff on ID22
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l Title of Presentation l Date of Presentation l Author
PROBLEMS FACED SO FAR…
• Samples had a very short lifetime in the beam.
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3 three minute scans run at the same position on the capillary
ZnO peak (left) with and ZIF 8 peak (right)
l Title of Presentation l Date of Presentation l Author
WHAT IS A SPACE GROUP?
• Categories developed by mathematical group theory• Describe the symmetry elements for unit cells
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