Excess proton hydrate structures with large proton polarizability in the channel of trioxaalkyl phosphate

Abstract

Complexes of tributyl phosphate (TBPO) and tris(10-chloro-3,6,9-trioxadecyl) phosphate (TODPO) with HAuCl₄ and their hydrates with various amounts of water were studied by FT-IR spectroscopy. TBPO with HAuCl₄ forms homoconjugated PO⁺H···OP ⇌ PO···H⁺OP hydrogen bonds with large proton polarizability. In hydrates of homoconjugated PO⁺H···OP ⇌ PO···H⁺OP complexes, H₅O₂⁺ is formed with a hydrogen bond having large proton polarizability. In the 1:1 mixture no H₃O⁺, but both H₅O₂⁺ and PO⁺H···OP ⇌ PO···H⁺OP homoconjugated bonds are present in the a 1:1 ratio. In the protonated and hydrated mixtures of TODPO no homoconjugated PO⁺H···OP ⇌ PO···H⁺OP hydrogen bonds and no H₅O₂⁺ species are found. In these complexes the proton and water molecules are present in the channels which show large proton polarizability. The behaviour of these protonated and hydrated channels is discussed with respect to the behaviour of the gramicidin channel.