Strong hydrogen bond-mediated complexation of H2PO4- by neutral bis-thiourea hosts

Article abstract of DOI:10.1016/S0040-4020(96)01094-0

Highly preorganized bis-thiourea receptors based on a xanthene spacer selectively (H₂PO₄^- > CH₃COO^- > Cl^-) bind dihydrogenphosphate via multitopic hydrogen bonding, giving stronger complexes with H₂PO₄^- than any synthetic neutral receptor known so far. The high complexation strengths are rationalized by the hydrogen bond donor strength of the thiourea groups and by host preorganization. The hydrogen bond acceptor strengths of the guest anions and, for small ions, guest solvation explain the observed selectivity of complexation in dimethyl sulfoxide (DMSO).