Morell Cerdà Marta, Amantia David, Costisella Burkhard, Houlton Andrew, Lippert Bernhard
Fachbereich Chemie, Universität Dortmund, 44221, Dortmund, Germany.
Dalton Trans. 2006 Aug 28(32):3894-9. doi: 10.1039/b603650c. Epub 2006 Jun 26.
Simultaneous metal coordination to N7 (Pt(II)) and N3 (Pd(II)) of N9-blocked guanine leads to a 10(4) fold acidification of the guanine-N(1)H position and hence to a virtual complete deprotonation of the N(1)H position at neutral pH. The chelate-tethered nucleobase ethylenediamine-N9-ethylguanine was employed and relevant acid-base equilibria were studied by pD dependent 1H NMR spectroscopy. CH2 resonances of the tether were assigned on the basis of NOESY and COSY experiments. Our findings suggest a plausible method of formation of a previously reported trinuclear Pt(II) complex of 9-ethylguanine with metals coordinated to N1, N3 and N7. According to this, a sequence with the first metal binding to N7, the second one binding to N3, and only the third one binding to N1 with deprotonation of this site is proposed.
N9位被封闭的鸟嘌呤与N7（Pt(II)）和N3（Pd(II)）同时发生金属配位，导致鸟嘌呤-N(1)H位置酸化10⁴倍，从而在中性pH下N(1)H位置几乎完全去质子化。使用了螯合连接的核碱基乙二胺-N9-乙基鸟嘌呤，并通过依赖于pD的¹H NMR光谱研究了相关的酸碱平衡。基于NOESY和COSY实验对连接链的CH₂共振进行了归属。我们的研究结果提出了一种形成先前报道的9-乙基鸟嘌呤与金属配位至N1、N3和N7的三核Pt(II)配合物的合理方法。据此，提出了一种序列，其中第一种金属与N7结合，第二种金属与N3结合，只有第三种金属与N1结合并使该位点去质子化。
