Anion binding in aqueous media by a tetra-triazolium macrocycle

abstract

Three tetra-triazole macrocycles were synthesized in good yields by the copper(I)-catalysed cycloaddition of bis-triazole azides and bis-alkynes. One of these was alkylated to give a cyclic tetra-triazolium receptor, which complexes anions strongly in competitive DMSO-water mixtures. In 1 : 1 DMSO-water, the tetracationic receptor exhibits a preference for the larger halides, bromide and iodide, with all halides associating more strongly than the oxoanion, acetate. The sulfate dianion is complexed far more strongly than any of the monobasic anions (K-a > 10(4) M-1). Quantum mechanics/molecular mechanics simulations corroborate the experimentally determined anion binding selectivity trends.

keywords

6-AMINOPICOLINIC ACID SUBUNITS; HYDROGEN-BONDS; ARYL-TRIAZOLE; SELECTIVE RECOGNITION; COMPUTER-PROGRAM; TERMINAL ALKYNES; RECEPTOR; CHLORIDE; COMPLEXATION; IONS

subject category

Chemistry

authors

White, NG; Carvalho, S; Felix, V; Beer, PD

our authors

acknowledgements

We thank Oxford Chemical Crystallography for the use of instruments, and Dr Amber L. Thompson for helpful discussions. NGW thanks the Clarendon Fund and Trinity College, Oxford for funding. SC thanks the FCT for the post-doctoral fellowship SFRH /BPD/42357/2007.

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