The main objectives are described as follows :
* To design new calixarene derivatives containing aliphatic and alicyclic amines and mixed donor atoms (sulfur and nitrogen) in which the distance between the phenolic oxygens and the amine nitrogens (or sulfur) is increased (-CH2-CH2-instead of -CH2-) in order to :
i) induce selective complexation with polluting cations (mercury, cadmium and lead) while reducing the accessibility of the phenol oxygens to interact with essential cations (Na+, K+, Ca2+, Mg2+);
ii) use the protonated calixamines and thiocalixamines for anion complexation with polluting anions (AsO4-3);
iii) investigate the hosting properties of the hydrophobic cavity for interaction with polluting chlorinated aliphatic and aromatic compounds.
* To incorporate these macrocycles in solid supports (natural products of Latin America, alumina, polymeric frameworks) for the development of recyclable materials and in membranes for the production of sensors for the detection of inorganic polluting ions.
* To put calixarene based decontaminants into action by testing their capabilities on polluted natural resources (water) and to compare them with the currently used ion exchange methods.
* Availability of recyclable solid materials for water purification of higher efficiency than the ones currently used based on the use of ion exchange systems.
* The development of new sensors based on these new materials for the detection of toxic metal cations in aqueous medium.
* Quantitative information regarding the amount of polluting agents in contaminated waters stored in a database prior and after treatment with new materials.
The key activities involve :
* Synthesis and characterisation of calixamines and thiocalixamines : phase transfer catalysis for the synthesis of derivatives will be fully explored. The new compounds are to be characterised by spectrometric techniques and X-ray crystallography. Experimental work will be assisted by computer modelling studies.
* Thermodynamic and kinetic studies : essential to the development of design protocols which will guide the synthetic programme in the later stages and so provide effective calixarenes as environmental scavengers is the understanding of the ion-solvent and ligand-solvent interactions embodied in the complexation and release processes involving macrocyclic ligands with metal cations, anions and neutral species. Calorimetry (thermodynamics) and flow methods (kinetics) will be the methods used.
* Comparative studies with ion exchange resins : for cation removal, based on the thermodynamics and kinetic investigations, assessment of ion-exchange selectivity will be tested with different commercially available resins while anion exchanges will be used to test anion selectivity.
* Incorporation of calixarene derivatives in supports and membranes : the strategy adopted aims to anchor calix(4)arene derivatives on solid supports (swollen cross-linked chloromethylated polystyrene matrices using Merrifield polymers of different mesh sizes and various contents of DVB and natural materials from Latin America) without affecting the active sites for interaction with polluting ions or with neutral species. Physico-chemical characterisation involve the use of a variety of techniques including thermogravimetric analysis and calorimetry. Considerable emphasis is to be placed of the recycling of these materials.
Funding SchemeCSC - Cost-sharing contracts
1900 La Plata
CV4 7AL Coventry