Department of Chemistry, University College London, 20 Gordon Street, London, UK WC1H 0AJ.
Dalton Trans. 2011 Nov 14;40(42):11248-57. doi: 10.1039/c1dt11086a. Epub 2011 Sep 22.
The geometries, relative energies and spectroscopic properties of a range of D-gluconate complexes of uranyl(VI) are studied computationally using density functional theory. The effect of pH is accommodated by varying the number of water and hydroxide ligands accompanying gluconate in the equatorial plane of the uranyl unit. For 1 : 1 complexes, the calculated uranyl ν(asym) stretching frequency decreases as pH increases, in agreement with previous experimental data. Three different gluconate chelating modes are studied. Their relative energies are found to be pH dependent, although the energetic differences between them are not sufficient to exclude the possibility of multiple speciation. (13)C NMR chemical shifts are calculated for the coordinated gluconate in the high pH mimics, and show good agreement with experimental data, supporting the experimental conclusion that the six-membered chelate ring is favoured at high pH. Attempts to improve the description of the aqueous environment via the addition of second solvation shell water molecules resulted in significantly worse agreement with experiment for ν(asym). The effect of increasing the gluconate concentration is modelled by calculating 1 : 2 and 1 : 3 uranyl : D-gluconate complexes.
使用密度泛函理论计算研究了一系列铀酰(VI)D-葡萄糖酸盐配合物的几何形状、相对能量和光谱性质。通过改变伴随葡萄糖酸盐在铀酰单元赤道平面中的水和氢氧化物配体的数量来适应 pH 的影响。对于 1:1 配合物，计算得到的铀酰 ν(asym)伸缩振动频率随 pH 的增加而降低，这与先前的实验数据一致。研究了三种不同的葡萄糖酸螯合模式。发现它们的相对能量随 pH 而变化，尽管它们之间的能量差异不足以排除多种形态存在的可能性。计算了高 pH 模拟物中配位葡萄糖酸的 (13)C NMR 化学位移，与实验数据吻合较好，支持了实验结论，即在高 pH 下六元螯合环更有利。通过添加第二溶剂化壳水分子来改进对水环境的描述的尝试，导致 ν(asym)与实验的吻合度显著降低。通过计算 1:2 和 1:3 铀酰：D-葡萄糖酸盐配合物来模拟葡萄糖酸盐浓度增加的影响。
