合成红色绿柱石中通道水分子构型及1H和23Na核磁共振谱表征

Channel-Water Molecular Pattern and 1H,23 Na NMR Spectra Representation in Synthetic Red Beryl

  • 摘要: 以水热法合成贫碱型红色绿柱石和天然富碱、贫碱型绿柱石为研究对象, 采用 VU,IR,NMR测试方法, 重点对绿柱石中通道水分子的构型及与钠离子的耦合关系进行研究。结果表明, 贫碱型水热法合成红色绿柱石中 Ⅰ型和 Ⅱ型通道水分子并存, 但以Ⅰ 型通道水分子的丰度明显占优。合成红色绿柱石的 1H NMR谱属典型的两自旋系, 分属两个独立的共振信号。中心共振谱峰 (δ=1.7× 1 0 -6)与 Be—OH—Al有关, 为 Ⅰ型通道水分子的表征。伴生共振谱峰 (δ=4.9× 1 0 -6)与 H—O…Na有关, 代表 Ⅱ型通道水分子。23 Na NMR谱中心线的化学位移随通道中 Na离子浓度的增大而发生有规律的变化, 表现为23 Na的共振谱峰自高场区向低场区偏移, 分裂强度增大, 裂距和半峰宽减小。同时, 1H NMR的峰形自双自旋系向单自旋系转化。证实合成红色绿柱石中通道水分子与碱金属离子之间存在明显的耦合关系。

     

    Abstract: The VU, IR and NMR testing methods are employed in this paper to investigate the coupling relationship between the channel water molecular pattern and the Na+ in the channels of beryls including the hydrothermal synthetic alkaline poor red beryl and the natural alkaline-rich or alkaline-poor beryl. The results show that type I and type II channel-water molecules coexist in alkaline-poor synthetic red beryl though the abundance of type I channel-water molecule is distinctively dominant. 1H NMR spectra, classified as the two typical spin systems, belong to two independent resonant signals respectively. The central NMR spectral peak (δ =1.7×10 -6) is related to Be-OH-Al, characteristic of type I channel water molecules. The associated NMR spectral peak (δ = 4.9×10 -6) is related to H-O...Na, characteristic of type II channel-water molecules. The chemical displacement of the central NMR spectral line of 23 Na shows a regular change with the increase in Na ion concentration in channels, characterized by the deviation of the 23 Na NMR spectral peak from the high magnetic field to the low magnetic field, the increase in split intensity and the decrease in split distance and semi peak width.At the same time, 1 H NMR peak shape is transformed from the bi-spin system into the mono-spin system, indicating a conspicuous coupling relationship between the channel-water molecules and alkaline metal ions of the synthetic red beryl.

     

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