Ionic Liquids

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• Ionic Liquids Inherent sensing and transduction
  of metal ion complexation
• EMRS Spring Meeting
• Strasbourg, France
• 10th June 2010

2
Me..

• Graduated with B.Sc (Hons) in Chemical
  Pharmaceutical Sciences, Dublin City University
  (2008).
• PhD. in Ionic Liquids and their use in the
  development of potential chemical sensors. Sept
  08
• Supervisors Dr. Aleksandar Radu Prof. Dermot
  Diamond

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Outline

• Ionic Liquids
• Polymeric Optodes
• Ionic Liquid PVC Optodes
• UV/Vis Characterisation
• Alternate Detection Techniques
• Wireless Radio Frequency Detection
• Electrochemical Impedance Spectroscopy
• Portable X-Ray Fluorescence

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Ionic Liquids

• Unique combination of
• ions that are liquid at room
• temperature
• Choice of ion pair can have
• dramatic impact on
• Density
• Viscosity
• Miscibility with Solvents

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Applications

• Synthesis Catalysis in Organic Chemistry
• gt Good thermal stability
• Electrochemistry
• gt Good Conductivity and a large electrochemical
  window
• Analytical Chemistry
• gt Stable stationary phase for separations

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Polymeric Optodes

• Typically contain up to 5 components
• Polymer Inert matrix to house active sensing
  components
• Plasticizer Lowers Tg of polymer to produce
  solid film
• Ion-Exchanger Facilitates Ion Transfer from aq.
  to organic phase
• Ionophore Selectively binds ion of interest
• Transducer Dye Produces optical response

PMMA optodes containing Spiropyran dye
3. A. Radu, R. Byrne, N. Alhashimy and D.
Diamond, Abstr. Pap. Am. Chem. Soc., 2006, 231,
41-INOR.
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Simple, 2-component optodes
Co2
Cu2

• P6,6,6,14DCA acts as
• plasticizer
• ion-exchanger
• ligand
• transducer dye
• Upon exposure to Cu2 and Co2

Cu2/Co2
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Multianalyte Recognition
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Binding Constants

• Best fit was found to be 2M for 1L

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Dicyanamide

• Pseudohalide, shown in literature to bind to an
  array of TM elements1
• Due to strong electron delocalisation across
  molecule, resulting in a variety of binding
  modes2
• Rich binding diversity results in many 1,2 and
  3-D co-ordinated networks reported
• Used to impart low viscosity in a new generation
  of Ionic Liquids

M
1. S. R. Batten, P. Jensen, B. Moubaraki, K. S.
Murray and R. Robson, Chem. Commun., 1998,
439-440. 2. S. R. Batten and K. S. Murray,
Coordination Chemistry Reviews, 2003, 246,
103-130.
DCA
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Interference Spectra

• Ni2 has been shown to bind to DCA4, yet
  produces no optical response

4. J. Kohout, L. Jager, M. Hvastijova and J.
Kozisek, J. Coord. Chem., 2000, 51, 169-218.
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RF Wireless Conductivity Detection

• In conjunction with CSIRO Laboratories,
• Melbourne, Australia
• Works by passing low voltage, low
• frequency AC signal from transmitting
• to receiving electrodes
• Sample is housed in an insulating
• container
• Conductive sample produces a signal
• as it passes through the electrode
• field

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RF Wireless Conductivity Detection

• Depending on pH, polyaniline (PAni) can switch
  between conductive and non-conductive forms
• Ink-jet printed Pani dispersion
• Strip housed in insulating container
• Response occured upon repeated
• exposure to acetic acid and ammonia

N. B. Clark and L. J. Maher, Reactive
Functional Polymers, 2009, 69, 594-600.
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Conductive Membranes

• WRF has the required sensitivity
• to distinguish between complexed
• and non-complexed membranes
• Edge effects occur as insulating
• material first enters and leaves
• electrode channel

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Screen Printed Electrodes

• Ag/AgCl ink used as conducting path
• Carbon Paste used as working electrode
• Insulating Layer defines the working area
• Conducting polymer (Poly (3-octylthiophene))
• is first dropcast to aid ionic to electronic
• Transition
• PVC-IL cocktail dropcast and allowed to dry

A. Morrin, A. J. Killard and M. R. Smyth,
Analytical Letters, 2003, 36, 2021-2039.
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Impedance Spectroscopy

• PVCIL 12 (w/w)

• PVCIL (11 w/w)

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Portable X-Ray Fluorescence

• Emitting x-rays knocks out electron in inner
  shell
• Vacancy is filled by atom from outer shell
• Filling of vacancy emits frequency
• XRF picks up frequency characteristic of element

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XRF Results

• Used to quantify DCA-
• binding preferentiality
• Co levels were found
• to be 45 lower
• Even as a mixture
• (21 CoCu (vol.))
• Co levels are 88 lower!

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Conclusions

• The Ionic Liquids P6,6,6,14DCA fulfils
  multiple roles in polymeric optodes
• Conductive membranes allow for detection via an
  array of techniques
• The relative ease of synthesis and diversity
  allows for the possibility of new ILs with
  greater selectivity

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Acknowledgements

• Drs. Aleksandar Radu, Robert Byrne and Professor
  Dermot Diamond
• Michele Zanoni, Bartosz Ziolkowski, Larisa Florea
  and Caroline Barry
• Drs. Noel Clarke and Matthius Hilder at CSIRO
• Cytec Industries
• DCU Research Career Start Fellowship 2008
• Science Foundation Ireland (grant 07/CE/I1147)
• Enterprise Ireland (grant 07/RFP/MASF812)

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• Thanks for listening!