Name: Andrew Kavanagh

 

 

Contact Details:

 

CLARITY: The Centre for Sensor Network Technologies,

National Centre for Sensor Research,

School of Chemical Sciences,

Dublin City University,

Dublin 9,

Ireland.

 

e-mail: andrew.kavanagh@dcu.ie

tel: 00353-1-7007604

 

 

 

Qualifications:

 

B.Sc in “Chemical and Pharmaceutical Sciences” – Dublin City University (2008)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Project Summary:

 

 

Metal-Ligand Complexation in Ionic Liquids.

 

Ionic Liquids (IL’s) are a class of molten salts that are the subject of diverse research interest worldwide. This intense research is most likely die to several advantageous physicochemical properties such as negligible vapour pressure, high thermal and electrochemical stability and miscibility with both aqueous and organic media[1]. They typically contain a bulky asymmetric organic cation and an organic/inorganic anion.

 

My research so far has been to synthesise IL’s, to study the consequences of metal ligand complex formation within these emerging new class of compounds and to characterize these changes both optically and structurally.

 

 

 

 

 

 

 

 

 

Figure 1: Cations and anions used in this study; i) trihexyltetradecylphosphonium,ii) triisobutylmethylphosphonium, iii) bis(trifluoromethanesulfonyl)amide, iv) toluene sulfonate, v) dodecylbenzene sulfonate, vi) dicyanamide, vii) methane sulfonate.

 

 

 

Case 1: trihexyltetradecylphosphonium dicyanamide [P6,6,6,14] [DCA].

 

 

The IL [P6,6,6,14][DCA] can easily be solidified into PVC membranes by dissolution with THF, once homogeneous the solution is then dropcast and allowed to dry overnight. The result is a hydrophobic solid surface where the IL acts as plasticizer, ion-exchanger and ligand for coordination with heavy metal ions.

An optical response is achieved upon coordination with Cu2+ (yellow), Co2+ (blue) and both ions simultaneously in solution (green). Multianalyte recognition is achieved through UV/Vis spectrometry, which discriminates ions based on two separate, distinct absorption maxima.

Polymeric membranes of this nature have been employed in various chemical sensing techniques, and typically contain up to 5 components. By manipulating the inherent properties of the IL, we can achieve drastic simplification in how these membranes function.

 

 

Figure 2: Colour changes seen in self-plasticized PVC membranes upon addition of a heavy metal salt.

 

 

 

 

 

Case 2: Varying the anion, thermally activated co-ordination.

 

IL’s vary greatly in their Lewis Acid/Base properties. By choosing an anion that will not readily donate an electron, the viscosity of the liquid can decrease as it cannot interact with its complemetary Lewis acid (in this case the cation of the IL).

An example of these low viscosity liquids are the tetraalkylphosphonium salts containing dodecylbenzenesulfonate [DBSA]- and toluenesulfonate [TOS]-.

These anions have solvating properties as opposed to co-ordinating properties with a given cation. Initially when a heavy metal solution is added to these IL’s, phase transfer occurs but co-ordination does not.

The reaction does however; proceed at elevated temperatures (80o) resulting in a clear colour change within the IL.

 

Alternating Detection Technique

 

The transduction mechanism in these membranes is convenient in that it produces an optical response. Transduction is detectable by a variety of techniques. By monitoring the conductivity change, there is potential for a decreased detection limit.

This work is in collaboration with researchers at the CSIRO Centre for Materials Science and Engineering in Melbourne Australia and focuses on monitoring the conductivity changes that occur upon coordination. CSIRO researchers have at their disposal a wireless conductivity monitoring device which can detect a conductive sample from within an insulating box.

Validation of this novel technique is needed by employing Electrochemical Impedance Spectroscopy (EIS) and by portable X-Ray Fluorescence (XRF).

 

 

 

 

 


  

 

 

 

 

 

Fig 3: Detection Systems® Wireless RF Monitoring Instrument.

Oral Presentations:

 

1.     Andrew Kavanagh, Matthius Hilder, Noel Clark, Dermot Diamond and Aleksandar Radu Ionic Liquids - Inherent Sensing and Transduction of Metal Ion complexation. European Materials Research Society – Spring Meeting, Strasbourg, France, June 2010.

2.     Andrew Kavanagh, Matthius Hilder, Noel Clark, Dermot Diamond and Aleksandar Radu The inherent physical, optical and conductivity properties of Ionic Liquid – polymeric membranes; a self indicating, simultaneous response upon coordination to transitional metal ions. Macro 2010, 43rd World Polymer Congress, Glasgow, Scotland, July 2010.

 

 

 

Poster Presentations:

 

 

1.     Andrew Kavanagh, Robert Byrne, Dermot Diamond, Aleksandar Radu Self-Indicating, Simultaneous Multianalyte recognition using an ionic liquid. Pittcon Conference & Exposition, Chicago, USA, March 2009.

2.     Andrew Kavanagh, Robert Byrne, Dermot Diamond, Aleksandar Radu Multifunctional Ionic Liquids and their use in the formation of coordinated structures. COIL-3, 3rd International Congress on Ionic Liquids, Cairns, Australia, May 2009.

 

 

 

 

 

 

 

 

 


[1] .             Welton T, Chemical Reviews, Vol. 99, pp., 2071 – 2083, 1999.