title: Mononucleotide recognition by cyclic trinuclear palladium(II) complexes containing 4,7-phenanthroline N,N bridges.
abstract: Reaction of [(dach)Pd(NO3)2] entities (dach = (R,R)-1,2-diaminocyclohexane, (S,S)-1,2-diaminocyclohexane) and 4,7-phenanthroline (phen) providing, respectively, 90 and 120 degrees bond angles, leads to the formation of two novel positively charged homochiral cyclic trinuclear metallacalix[3]arene species [((R,R)-1,2-diaminocyclohexane)Pd(phen)]3(NO3)6 (2a) and [((S,S)-1,2-diaminocyclohexane)Pd(phen)]3(NO3)6 (2b). These species have been characterised by 1)H NMR and X-ray diffraction methods (2b), showing that they possess accessible cavities suited for supramolecular recognition processes. We prove, indeed, from 1H NMR studies the inclusion of mononucleotides inside the cavity of the trinuclear species [(ethylenediamino)Pd(phen)]3(6+) (1), [((R,R)-1,2-diaminocyclohexane)Pd(phen)]3(6+) (2a) and [((S,S)-1,2-diaminocyclohexane)Pd(phen)]3(6+) (2b) in aqueous solution. Association constants (K(ass)) range from 85 +/- 6 M(-1) for the interaction between [(ethylenediamine)Pd(phen)]3(6+) and adenosine monophosphate to 37 +/- 4 M(-1) for the interaction between [(1,2-diaminocyclohexane)Pd(phen)]3(6+) and thymidine monophosphate. We invoke the synergy of electrostatic, anion-pi and pi-pi interactions to explain the recognition of mononucleotides inside the cavity of the metallacalix[3]arenes.
authors.affiliation: Departamento de Química Inorgánica, Universidad de Granada, Av. Fuentenueva S/N, E-18071 Granada, Spain.
authors.forename: Miguel A
authors.initials: MA
authors.lastname: Galindo
authors.forename: Jorge A R
authors.initials: JA
authors.lastname: Navarro
authors.forename: M Angustias
authors.initials: MA
authors.lastname: Romero
authors.forename: Miguel
authors.initials: M
authors.lastname: Quirós
mesh_terms: D000249:Adenosine Monophosphate / Q000737:chemistry; D003568:Cytidine Monophosphate / Q000737:chemistry; D047028:Macrocyclic Compounds; D015394:Molecular Structure; D009711:Nucleotides / Q000737:chemistry*; D009942:Organometallic Compounds / Q000737:chemistry; D010165:Palladium / Q000737:chemistry*; D010618:Phenanthrolines / Q000737:chemistry; D013938:Thymidine Monophosphate / Q000737:chemistry
chemical_list: D047028:Macrocyclic Compounds; D009711:Nucleotides; D009942:Organometallic Compounds; D010618:Phenanthrolines; D013938:Thymidine Monophosphate; D000249:Adenosine Monophosphate; D010165:Palladium; D003568:Cytidine Monophosphate