Solution state structure determination of silicate oligomers by 29Si NMR spectroscopy and molecular modeling
Solution state structure determination of silicate oligomers by 29Si NMR spectroscopy and molecular modeling
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DOI：
10.1021/ja0559202
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发表时间：
2006-02-22
影响因子：
15
通讯作者：
Dixon, DA
中科院分区：
文献类型：
--
作者：
Cho, H;Felmy, AR;Dixon, DA
通过Si-29富硅样品的核磁共振同核相关实验，发现了9种新的溶液态硅酸盐低聚物存在的证据。除了增强信号灵敏度外，同位素富集还增加了Si-29-Si-29双键标量耦合的可能性，这是在二维实验中观察核间相关所必需的。通过高数字分辨率获得的实验和模拟交叉峰的比较，验证了所提出的分配。核磁共振数据显示的核间连通性表明，这些低聚物中的一些可以具有多个立体异构体，包括构象和/或非对映体。通过电子结构计算研究了这些低聚物及其可能的立体异构体的稳定性。
Evidence for nine new solution state silicate oligomers has been discovered by Si-29 NMR homonuclear correlation experiments of Si-29-enriched samples. In addition to enhancing signal sensitivity, the isotopic enrichment increases the probability of the Si-29-Si-29 two-bond scalar couplings that are necessary for the observation of internuclear correlations in 2-D experiments. The proposed assignments are validated by comparisons of experimental and simulated cross-peaks obtained with high digital resolution. The internuclear connectivity indicated by the NMR data suggests that several of these oligomers can have multiple stereoisomers, including conformers and/or diastereomers. The stabilities of these oligomers and their possible stereoisomers have been investigated by electronic structure calculations.