title: Intramolecular cation-pi interactions as the driving force to restrict the conformation of certain nucleosides.
abstract: Despite the well-established importance of intermolecular cation-pi interactions in molecular recognition, intramolecular cation-pi interactions have been less studied. Here we describe how the simultaneous presence of an aromatic ring at the 5'-position of an inosine derivative and a positively charged imidazolium ring in the purine base drive the conformation of the nucleoside toward a very major conformer in solution that is stabilized by an intramolecular cation-pi interaction. Therefore, the cation-pi interaction between imidazolium ions and aromatic rings can also be proposed in the design of small molecules where this type of interaction is desirable. The imidazolium ion can be obtained by a simple acidification of the pH of the media. So a simple change in pH can shift the conformational equilibrium from a random to a restricted conformation stabilized by an intramolecular cation-pi interaction. Thus the here described nucleosides can be considered as a new class of pH-dependent conformationally switchable molecules.
authors.affiliation: Instituto de Química Médica (CSIC), Juan de la Cierva 3, E-28006 Madrid, Spain.
authors.forename: Elena
authors.initials: E
authors.lastname: Casanova
authors.forename: Eva-María
authors.initials: EM
authors.lastname: Priego
authors.forename: María-Luisa
authors.initials: ML
authors.lastname: Jimeno
authors.forename: Leire
authors.initials: L
authors.lastname: Aguado
authors.forename: Ana
authors.initials: A
authors.lastname: Negri
authors.forename: Federico
authors.initials: F
authors.lastname: Gago
authors.forename: María-José
authors.initials: MJ
authors.lastname: Camarasa
authors.forename: María-Jesús
authors.initials: MJ
authors.lastname: Pérez-Pérez
mesh_terms: D006863:Hydrogen-Ion Concentration; D007288:Inosine / Q000737:chemistry; D009682:Magnetic Resonance Spectroscopy; D008968:Molecular Conformation; D015394:Molecular Structure; D009705:Nucleosides / Q000737:chemistry*; D011789:Quantum Theory; D012333:RNA, Messenger / Q000737:chemistry*
chemical_list: D009705:Nucleosides; D012333:RNA, Messenger; D007288:Inosine