Intramolecular cation-pi interactions as the driving force to restrict the conformation of certain nucleosides.
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.
Casanova
Elena
E
Instituto de Química Médica (CSIC), Juan de la Cierva 3, E-28006 Madrid, Spain.
Priego
Eva-María
EM
Jimeno
María-Luisa
ML
Aguado
Leire
L
Negri
Ana
A
Gago
Federico
F
Camarasa
María-José
MJ
Pérez-Pérez
María-Jesús
MJ
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*
D009705:Nucleosides; D012333:RNA, Messenger; D007288:Inosine