1. Analytical Research Seminar
NANOPARTICLES DERIVED FROM A GROUP OF UNIFORM MATERIALS BASED ON ORGANIC SALTS
Analytical Research Seminar
Aaron Tesfai
Warner Research Group
Department of Chemistry.
Louisiana State University. Baton Rouge,LA 70803

2. Outline Introduction to Ionic Liquids (ILs) Brief history
Common cation/anion combinations
Properties of ILs
Group of Uniform Materials Based on Organic Salts (GUMBOS)
Synthesis and Characterization of Micro- and NanoGUMBOS
Surfactantless Melt-Emulsion-Quench
Surfactant-Assisted-Melt-Emulsion-Quench
Reverse Micelle
Magnetic Particles from GUMBOS
Synthesis and characterization of [Bm2Im][FeCl4] GUMBOS particles
Magnetic susceptibility of [Bm2Im][FeCl4] GUMBOS particles

3. Ionic Liquids (ILs)
Ionic liquids are defined as organic salts with melting points at or below 100 °C
Liquid at room temperature (room temperature ionic liquids RTILs)
Solid above room temperature (frozen ionic liquids)
The name ILs was first used by a Latvian-German chemist Paul Walden
Walden discovered the first ionic liquid, ethyl ammonium nitrate with a melting point of 12 °C in 1914
The term ILs used to distinguish these compounds from inorganic salts that melt at high temperature
Low melting point - asymmetry between the ions prevent formation of stable crystal lattice (“frustrated crystal packing”)
Welton T. Chem Rev 1999, 99,
Philippe Hapiot and Corinne Lagrost Chem. Rev. 2008, 108, 2238–2264
Del Po’polo, M. G.; Voth, G. A. J. Phys. Chem. B 2004, 108,
P. Walden, Bull. Acad. Imper. Sci. (St. Petersburg) 1800 (1914)

4. Common Cations and Anions
1-alkyl pyridinium
1-alkyl-3-methyl-imidazolium
Tetraalkyl-phosphonium
Tetraalkyl-ammonium
R = Ethyl, Butyl, Hexyl, Octyl and Decyl
Common alkyl (R-) chains:
Common anions:
bis(trifluoromethylsulfonyl)imide
hexafluorophosphate
tetrafluoroborate
nitrate

5. Properties of Ionic Liquids
Tunability
Thermal stability
Dissolve many organic and inorganic materials
Low volatility
Environmentally friendly

6. Group of Uniform Materials Based on Organic Salts (GUMBOS)
1-butyl-2,3-dimethylimidazolium tetrachloroferrate
M.P. -2 °C
1,3,3-Trimethyl-2-[7-(1,3,3-trimethyl-1,3-dihydro-indol-2-ylidene)-hepta-1,3,5-trienyl]-3H-indolium bis(trifluoromethylsulfonyl)imide
M.P. > 120 °C
Tesfai et al. ACS Nano accepted.
Bwambok et al. submitted to ACS Nano 2009.

7. Objectives
To investigate the use of GUMBOS that are solid above room temperature for possible GUMBOS-based nano- and micro- particle synthesis
To characterize the nano- and microGUMBOS
Scanning Electron Microscopy (SEM)
Transmission Electron Microscopy (TEM)
Differential Interference Contrast (DIC)
Fluorescence Microscopy
Atomic Force Microscopy
To dope the GUMBOS and investigate the possibility of using nanoGUMBOS to entrap various materials such as drug molecules

8. Synthesis and Characterization of Micro- and NanoGUMBOS
Surfactantless Melt-Emulsion-Quench
Surfactant-Assisted Melt-Emulsion-Quench
Reverse Micelle

9. GUMBOS Used [bm2Im][PF6]
[1-butyl-2,3-dimethylimidazolium] [hexafluorophosphate]
GUMBOS
Melting point
Miscibility with H2O
[1-butyl-2,3-dimethylimidazolium] [hexafluorophosphate]
42 °C No

10. Surfactantless Synthesis of NanoGUMBOS
1. Add 25 mg of GUMBOS into 8 mL of DI water
2. Heat mixture at 70 °C
3. Homogenize solution for 10 min, Probe sonication for 10 min
4. Freeze mixture in an ice water bath 1 2 4 3
Tesfai et al. Nano Lett. 2008, 8,

11. Characterization of NanoGUMBOS
SEM
TEM
Electron micrographs of [bm2Im][PF6] nanoGUMBOS synthesized using surfactantless synthesis: (a) SEM image showing an average nanoparticle diameter of 90 ± 32 nm. (b) TEM image with an average nanoparticle diameter measured as 88 ± 34 nm.
Tesfai et al. Nano Lett. 2008, 8,

12. Surfactantless Synthesis: Nile Red Doped NanoGUMBOS
(A) solid [Bm2Im][PF6]
(B) melted [Bm2Im][PF6]
(C) o/w emulsion
(D) [Bm2Im][PF6] nanoparticle crop
Tesfai et al. Nano Lett. 2008, 8,

13. Surfactantless Synthesis : SEM and Optical Microscopy (DIC) and (Fluorescence) of microGUMBOS
Solid [bm2Im][PF6] microGUMBOS with average diameters of ~ 3-μm imaged with (a) SEM, (b) Optical microscopy (DIC), (c) Optical microscopy (fluorescence), (d) Overlay of DIC and fluorescence.
Tesfai et al. Nano Lett. 2008, 8,

14. Synthesis and Characterization of Micro- and NanoGUMBOS
Surfactantless-Melt-Emulsion-Quench
Surfactant Assisted-Melt-Emulsion-Quench
Reverse Micelle

15. Surfactant-Assisted Synthesis of NanoGUMBOS
1. Add 1% w/v Brij-35 in DI water
2. Add 25 mg of GUMBOS to mixture and placed in water bath set to 70 °C
3. Homogenize solution for 10 min, Probe Sonication for 10 min
4. Freeze mixture in an ice water bath 1 3 2 4
Tesfai et al. Nano Lett. 2008, 8,

16. Surfactant-Assisted Synthesis: TEM of NanoGUMBOS
Representative TEM image of 45 ± 7 nm [bm2Im][PF6] nanoGUMBOS synthesized using surfactant-assisted synthesis, employing Brij-35.
Tesfai et al. Nano Lett. 2008, 8,

17. Synthesis and Characterization of Micro- and NanoGUMBOS
Surfactantless-Melt-Emulsion-Quench
Surfactant Assisted-Melt-Emulsion-Quench
Reverse Micelle

18. Surfactant Employed for Reverse Micelle Synthesis: Aerosol-OT (AOT)
Sodium bis(2-ethyl-hexyl)sulfosuccinate (AOT)
Double chain amphiphile
Able to form reverse micelles
Able to solubilize water
R value (wo): [water]/[surfactant]
AOT Reverse Micelle
Bulk
Heptane
Continuum
Inner Bulk Water
AOT Interface
Bound Water

19. Basic Processes for Nanoparticle Formation within AOT Reverse Micelles
0.1 M AOT
in 5 mL heptane
120 μL of M
[Bm2Im][Cl]
in water A
[Na][BF4] B
Tesfai et al. ACS Nano accepted

20. TEM Images of [Bm2Im][BF4] NanoGUMBOS
Reagent
Concentration (M)
Particle Size
(nm)
Standard
Deviation (nm)
A: 0.2
14.7
± 2.2
B: 0.4
20.8
± 1.8
C: 0.5
34.3
± 4.8
D: 0.6
68.0
± 17
Tesfai et al. ACS Nano accepted

21. Size Distributions of [Bm2Im][BF4] NanoGUMBOS
Synthesized in water-containing AOT reverse micelles at various reagent concentrations: [AOT] = 0.1 M; molar reagent concentrations: 0.2, 0.4, 0.5, and 0.6 M.
Tesfai et al. ACS Nano accepted.

22. Tapping Mode AFM Images of [Bm2Im][BF4] NanoGUMBOS
220 nm
220 nm B B
0.4 M [Bm2Im][BF4] 12 m 12 m C C
200 nm
200 nm D D 2 m 2 m
(A) 60 × 60 μm2 topographical image and (B) simultaneously acquired phase image. (C) Zoom-in view 12 × 12 μm2 view and (D) corresponding phase channel.
Tesfai et al. submitted to ACS Nano
Tesfai et al. ACS Nano accepted.

23. Conclusions
NanoGUMBOS (SEM) were obtained with average diameters of 90 nm using Surfactantless-Melt-Emulsion-Quench-Technique.
TEM was in good agreement with SEM yielding average diameters of 88 nm (Surfactantless-Melt-Emulsion-Quench-Technique).
MicroGUMBOS (SEM) were obtained with average diameters of ~3 μm (Surfactantless-Melt-Emulsion-Quench-Technique).
Doping the microGUMBOS suggests that they may be used to entrap various materials including drugs.
The use of an emulsifying agent (Surfactant-Assisted-Melt-Emulsion-Quench-Technique)yields nanoGUMBOS of ~45 nm in diameter.
Smaller particle size
Size control
A facile and reproducible method for synthesizing four distinct sizes of nanoGUMBOS has been developed (Reverse Micelle Synthesis).
NanoGUMBOS size was influenced by increasing reagent concentration within each reverse micelle.

24. Magnetic Particles From GUMBOS

25. Applications of Magnetic Nanoparticles
Magnetothermal
Iron oxide magnetic nanoparticles injected
In tumor
Application of external magnetic field
Drug Targeting
Superparamagnetic iron oxide nanoparticles are guided towards the lungs in the presence of an external magnetic field
Amirfazli, A. Nature Nanotech. 2007, 8,  

26. Objectives
To investigate the use of magnetic GUMBOS for possible GUMBOS-based particle synthesis
To characterize the GUMBOS particles
Transmission Electron Microscopy (TEM)
Atomic Force Microscopy

27. Magnetic Particles from GUMBOS
Synthesis and characterization of [Bm2Im][FeCl4] GUMBOS particles
Magnetic susceptibility of [Bm2Im][FeCl4] GUMBOS particles

28. Basic Processes for Magnetic Particle Formation within AOT Reverse Micelles.
0.1 M AOT
in 5 mL heptane
120 μL of M
[FeCl3].6H2O
in water B
0.1 M AOT
in 5 mL heptane
120 μL of M
[Bm2Im][Cl]
in water A
Tesfai et al. ACS Nano accepted.

29. TEM Images of Magnetic GUMBOS Particles
Micrographs of magnetic [Bm2Im][FeCl4] GUMBOS particles obtained from TEM revealing mean particle sizes of (A) 98.0 ± 17 nm and (B) ± 26 nm.
Reagent Concentration (M)
Particle Size (nm)
Standard Deviation (nm)
A: 0.3 98
± 17
B: 0.4
199
± 26
Tesfai et al. ACS Nano accepted.

30. Size Distributions of Magnetic GUMBOS Particles
[AOT] = 0.1 M; molar reagent concentrations: 0.3 and 0.4 M.
Tesfai et al. ACS Nano accepted.

31. Tapping Mode AFM Images of [Bm2Im][FeCl4] GUMBOS Particles
0.3 M [Bm2Im][FeCl4]
0.4 M [Bm2Im][FeCl4]
(A) Topographical image of magnetic nanoGUMBOS with a diameter near 100 nm and (B) the matching phase image. (C) Topography of 200-nm GUMBOS Particles and (D) the corresponding phase frame.
Tesfai et al. ACS Nano accepted.

32. Absorption Spectra of Bulk [Bm2Im][FeCl4]
Tesfai et al. ACS Nano accepted.
1Hayashi, S. et al. Chem. Lett. 2004, 33,

33. Magnetic Susceptibility of Bulk [Bm2Im][FeCl4] Alongside [Bm2Im][FeCl4] NanoGUMBOS
Magnetic Response (emu/g)
[BmIm][FeCl4]
1 40.6x10-6
[HmIm][FeCl4]
x 10-6
[OmIm][FeCl4]
x 10-6
GUMBOS/nanoGUMBOS
Magnetic Response (emu/g)
[Bm2Im][FeCl4] GUMBOS
34.3 x 10-6
[Bm2Im][FeCl4] nanoGUMBOS
1Hayashi, S.; Hamaguchi, H.-o. Chemistry Letters. 2004, 33, 1590.
Tesfai et al. ACS Nano accepted.

34. Conclusions
Two distinct sizes of magnetic nanoGUMBOS were synthesized and characterized
Particle size was influenced by increasing reagent concentration in each reverse micelle.
UV-Vis spectrum confirmed the well known characteristic peaks of FeCl4 for the bulk magnetic GUMBOS.
Both the bulk and nanoGUMBOS demonstrated to be magnetic

35. Acknowledgements Prof. Isiah M. Warner
Postdoctoral Research Associates
Warner Research Group
Garno Research Group
National Science Foundation (NSF)
National Institutes of Health (NIH)
Phillip W. West Endowment 35