Multifunctional ionic liquids and their use in the formation of co-ordinated structures
Kavanagh, Andrew and Byrne, Robert and Diamond, Dermot and Radu, Aleksandar (2009) Multifunctional ionic liquids and their use in the formation of co-ordinated structures. In: Coil-3 2009 - 3rd International Congress on Ionic Liquids, 31 May - 4 June 2009, Cairns, Australia.
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We report the use of phosphonium based ionic liquids (ILs) as multifunctional systems for the formation of transition metal ion coordinated polymers. The ILs studied included a tetraalkylated phosphonium cation; [PCnH2n+1]+ and the anions dicyanamide [DCA]- , bis(trifluoromethanesulfonyl)amide [NTf2]-, tosylate [TOS]-,
and dodecylbenzenesulfonate [DBSA]-. [DCA]- and other pseudohalide anions such as tricyanomethanide [TCM]- have been shown to co-ordinate to heavy metal centres1.
A survey of the literature shows many reports in which [DCA]- (as an alkali salt) has been shown to co-ordinate to these transition metals in various 2-D and 3-D
topologies and most notably in structures exhibiting magnetic properties2. We have studied the IL [P6,6,6,14][DCA] as a self-indicating, simultaneous,
multianalyte recognition system for heavy metal ions such as Cu2+ and Co2+. When incorporated into a polymer membrane, this system maintains all these attractive
features with the added bonus of the IL now being self-plasticizing. A system like this can be viewed as a building block for future chemical sensing platforms; where the system itself is responsive toward an analyte, thereby eliminating the need for a reactive chromophore.
Other anions mentioned are considered to be “soft” or non-coordinating. We have used heat to change the chemistry of these anions, resulting in ion coordination to
previously solvating anions. These solvating anions have in common a sulfoxide moiety that can co-ordinate to a given heavy metal.3 The formation of these structures
has been characterized via UV/Vis, Infrared and Raman Spectroscopy.
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