ABSTRACT

The conformational changes of the homooxa adamantyl ketones 1 and 2, as well as of the calix[4]arene analogue derivative 3, all in the cone conformation, upon Pb²⁺ complexation were investigated by ¹H, ¹³C, ²⁰⁷Pb NMR and proton spin-lattice relaxation times (T₁) experiments. The X-ray crystal structures of ketones 1 and 3 were determined. The inclusion of an acetonitrile molecule in the hydrophobic cavity of the ligands was observed in the solid state. In solution, inclusion was observed only in the case of Pb²⁺ ⊂ ketone 3 complex. DFT calculations were also performed to complement the NMR conformational analysis and to bring further insights to the cation complexation. The data confirmed the formation of 1:1 complexes between Pb²⁺ and the ligands, and that the cation is located inside the cavity defined by the phenoxy and carbonyl oxygen atoms. In general, the ligand conformations became closer to a regular cone upon complexation, with the binding models found for the three ketones through the NMR studies corroborated by the DFT calculations.

摘要

通过1 H 、13 ^C、²⁰⁷ Pb NMR^和_ _ _ ^_质子自旋晶格弛豫时间 ( T ₁ ) 实验。确定了酮1和3的 X 射线晶体结构。在固态下观察到在配体的疏水腔中包含乙腈分子。在溶液中，仅在 Pb ²⁺ ⊂ 酮3的情况下观察到夹杂物复杂的。还进行了 DFT 计算以补充 NMR 构象分析并进一步了解阳离子络合。^{数据证实了Pb 2+}和配体之间形成了1:1的配合物，并且阳离子位于由苯氧基和羰基氧原子定义的空腔内。一般来说，配体构象在络合时变得更接近规则锥体，通过核磁共振研究发现的三种酮的结合模型得到了 DFT 计算的证实。