Metal complexes of 6-pyrazolylpurine derivatives as models for metal-mediated base pairs.
6-(3,5-Dimethylpyrazol-1-yl)purine has recently been introduced as an artificial nucleobase for the specific recognition of canonical nucleobases via the formation of a metal-mediated base pair. We report here the synthesis and structural characterization by single crystal X-ray diffraction analysis of a series of metal complexes of the corresponding alkylated model nucleobases 9-methyl-6-(3,5-dimethylpyrazol-1-yl)purine 2 and 9-methyl-6-pyrazol-1-yl-purine 7. The sterically more demanding ligand 2 forms the Cu(2+) complexes [Cu(2)(NO3)2] and [Cu(2)Cl2] with a 1:1 stoichiometry of ligand and metal ion. In contrast, ligand 7 forms complexes [Cu(7)2(NO3)](NO3) and [Ag(7)2](ClO4) with a 2:1 stoichiometry. The molecular structures of [Cu(2)(NO3)2] and [Cu(2)Cl2] confirm the previously suggested coordination pattern, i.e. Cu(2+) is coordinated via the pyrazole nitrogen atom and the purine N7 position. The fact that different relative orientations of the two ligands in [Cu(7)2(NO3)](NO3) and [Ag(7)2](ClO4) are observed allows the prediction that the corresponding metal-mediated homo base pairs should be stable both in regular antiparallel-stranded and in the rare parallel-stranded double helices.
Westfälische Wilhelms-Universität Münster, Institut für Anorganische und Analytische Chemie, Corrensstr. 28/30, 48149 Münster, Germany; Westfälische Wilhelms-Universität Münster, NRW Graduate School of Chemistry, 48149 Münster, Germany.
Indranil
I
Sinha
Westfälische Wilhelms-Universität Münster, Institut für Anorganische und Analytische Chemie, Corrensstr. 28/30, 48149 Münster, Germany.
Alexander
A
Hepp
Westfälische Wilhelms-Universität Münster, Institut für Anorganische und Analytische Chemie, Corrensstr. 28/30, 48149 Münster, Germany.
Jutta
J
Kösters
Westfälische Wilhelms-Universität Münster, Institut für Anorganische und Analytische Chemie, Corrensstr. 28/30, 48149 Münster, Germany; Westfälische Wilhelms-Universität Münster, NRW Graduate School of Chemistry, 48149 Münster, Germany. Electronic address: mueller.j@uni-muenster.de.
Jens
J
Müller
D056831:Coordination Complexes / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology; D003300:Copper / Q000737:chemistry*; D011687:Purines / Q000737:chemistry*; D012834:Silver / Q000737:chemistry*
C000598023:6-(3,5-dimethylpyrazol-1-yl)purine; D056831:Coordination Complexes; D011687:Purines; D012834:Silver; D003300:Copper
DNA; Metal-mediated base pairs; Nucleobases