Second generation silver(I)-mediated imidazole base pairs

Abstract

SummaryThe imidazole–Ag(I)–imidazole base pair is one of the best-investigated artificial metal-mediated base pairs. We show here that its stability can be further improved by formally replacing the imidazole moiety by a 2-methylimidazole or 4-methylimidazole moiety. A comparison of the thermal stability of several double helices shows that the addition of one equivalent of Ag(I) leads to a 50% larger increase in the melting temperature when a DNA duplex with methylated imidazole nucleosides is applied. This significant effect can likely be attributed to a better steric shielding of the metal ion within the metal-mediated base pair.

4-(2′-Pyridyl)imidazole as an artificial nucleobase in highly stabilizing Ag(I)-mediated base pairs

“…Table 1 gives an overview of the sequences used in this study. An analogous 26mer sequence has previously been investigated with other artificial metal-mediated base pairs [25,30], allowing a direct comparison of the results. Similarly, various [14,[26][27][28][29]35].…”

Metal complexes of 6-pyrazolylpurine derivatives as models for metal-mediated base pairs

“…As numerous metal-mediated base pairs have been reported with a central Ag + ion [6,11,13,14,18,26,27,49], the coordination of Ag + to the model nucleobase 7 was probed, too. Upon reaction of 7 with AgClO 4 , complex [Ag(7) 2 ](ClO 4 ) 9 was obtained.…”

“…While metal-mediated base pairs can be formed from the canonical pyrimidine nucleobases cytosine or thymine [9][10][11][12], the majority of examples has been reported with artificial nucleobases, e.g. imidazole [6,13,14], hydroxypyridone [15,16], salen [17], or 6-substituted purines [18][19][20][21]. Metal-mediated base pairs may even contain two metal ions per base pair [22][23][24][25].…”

A tridentate “click” nucleoside for metal-mediated base pairing

“…T-Hg 2+ -T or C-Ag + -C [7][8][9]), specifically designed artificial nucleosides only (e.g. imidazole-Ag + -imidazole [10,11], hydroxypyridone-Cu 2+ -hydroxypyridone [12], salen-Cu 2+ [13,14], or pyridine-2,6-dicarboxylate-Cu 2+ -pyridine [15]) or mixtures of both (e.g. 1-deazaadenine-Ag + -thymine [16]).…”