title: 6-Substituted purines containing thienyl or furyl substituents as artificial nucleobases for metal-mediated base pairing.
abstract: The artificial nucleobases 6-(2'-thienyl)-purine (6TP) and 6-(2'-furyl)-purine (6FP) have been investigated in terms of their applicability in metal-mediated base pairs. In principle, these nucleobases should be capable of providing an S,N- and O,N-coordination environment, respectively. Two metal complexes have been synthesized and structurally characterized, using the N9-methylated derivatives of 6TP and 6FP as model nucleobases. The silver(I) complex [Ag(9-Me6TP)(CH3CN)(NO3)]n is of polymeric nature. The thienyl substituent is not involved in metal binding. In contrast, the dinuclear copper(II) complex [Cu(9-Me6FP)Cl2(OH2)]2 clearly shows that the furyl substituent can participate in the coordination of the metal ion. Oligonucleotide double helices comprising a 6TP:6TP or a 6FP:6FP mispair are slightly stabilized in the presence of silver(I). However, a distinction between the formation of a metal-mediated base pair and an unspecific binding event cannot be finally made. Based on these studies, it is proposed that the formation of Hoogsteen-type metal-mediated base pairs should be the more promising alternative compared with the originally anticipated Watson-Crick-type metal-mediated base pairs.
authors.affiliation: Westfälische Wilhelms-Universität Münster, Institut für Anorganische und Analytische Chemie, Corrensstr. 28/30, 48149 Münster, Germany. mueller.j@uni-muenster.de.
authors.forename: Indranil
authors.initials: I
authors.lastname: Sinha
authors.forename: Jutta
authors.initials: J
authors.lastname: Kösters
authors.forename: Alexander
authors.initials: A
authors.lastname: Hepp
authors.forename: Jens
authors.initials: J
authors.lastname: Müller
mesh_terms: D020029:Base Pairing; D056831:Coordination Complexes / Q000737:chemistry*; D003300:Copper / Q000737:chemistry*; D008670:Metals / Q000737:chemistry; D008958:Models, Molecular; D011687:Purines / Q000737:chemistry*; D012834:Silver / Q000737:chemistry*
chemical_list: D056831:Coordination Complexes; D008670:Metals; D011687:Purines; D012834:Silver; D003300:Copper; C030985:purine