title: Host-Guest Chemistry: Oxoanion Recognition Based on Combined Charge-Assisted C-H or Halogen-Bonding Interactions and Anion⋅⋅⋅Anion Interactions Mediated by Hydrogen Bonds.
abstract: Several bis-triazolium-based receptors have been synthesized and their anion-recognition capabilities have been studied. The central chiral 1,1'-bi-2-naphthol (BINOL) core features either two aryl or ferrocenyl end-capped side arms with central halogen- or hydrogen-bonding triazolium receptors. NMR spectroscopic data indicate the simultaneous occurrence of several charge-assisted aliphatic and heteroaromatic C-H noncovalent interactions and combinations of C-H hydrogen and halogen bonding. The receptors are able to selectively interact with HP2 O7 (3-) , H2 PO4 (-) , and SO4 (2-) anions, and the value of the association constant follows the sequence: HP2 O7 (3-) >SO4 (2-) >H2 PO4 (-) . The ferrocenyl end-capped 7(2+) ⋅2 BF4 (-) receptor allows recognition and differentiation of H2 PO4 (-) and HP2 O7 (3-) anions by using different channels: H2 PO4 (-) is selectively detected through absorption and emission methods and HP2 O7 (3-) by using electrochemical techniques. Significant structural results are the observation of an anion⋅⋅⋅anion interaction in the solid state (2:2 complex, 6(2+) ⋅[H2 P2 O7 ](2-) ), and a short C-I⋅⋅⋅O contact is observed in the structure of the complex [8(2+) ][SO4 ]0.5 [BF4 ].
authors.affiliation: Departamento de Química Orgánica, Universidad de Murcia, Campus de Espinardo, 30100, Murcia, Spain.
authors.forename: Lidia
authors.initials: L
authors.lastname: González
authors.affiliation: Departamento de Química Orgánica, Universidad de Murcia, Campus de Espinardo, 30100, Murcia, Spain.
authors.forename: Fabiola
authors.initials: F
authors.lastname: Zapata
authors.affiliation: Departamento de Química Orgánica, Universidad de Murcia, Campus de Espinardo, 30100, Murcia, Spain. antocaba@um.es.
authors.forename: Antonio
authors.initials: A
authors.lastname: Caballero
authors.affiliation: Departamento de Química Orgánica, Universidad de Murcia, Campus de Espinardo, 30100, Murcia, Spain. pmolina@um.es.
authors.forename: Pedro
authors.initials: P
authors.lastname: Molina
authors.affiliation: Departamento de Química Orgánica, Facultad de Farmacia, Universidad de Valencia, 46100, Valencia, Spain.
authors.forename: Carmen
authors.initials: C
authors.lastname: Ramírez de Arellano
authors.affiliation: Instituto de Química Médica, Consejo Superior de Investigaciones Científicas (CSIC), Juan de la Cierva, 3, 28006, Madrid, Spain. ibon@iqm.csic.es.
authors.forename: Ibon
authors.initials: I
authors.lastname: Alkorta
authors.affiliation: Instituto de Química Médica, Consejo Superior de Investigaciones Científicas (CSIC), Juan de la Cierva, 3, 28006, Madrid, Spain.
authors.forename: José
authors.initials: J
authors.lastname: Elguero
keywords: anions; density functional calculations; host-guest systems; noncovalent interactions; receptors