化学
构象异构
吡啶
菲咯啉
亚甲基
结晶学
立体化学
固态
衍生工具(金融)
金属
分子
药物化学
物理化学
有机化学
金融经济学
经济
作者
David J. Hernández,Hugo Vázquez‐Lima,Patricia Guadarrama,Diego Martínez‐Otero,Iván Castillo
标识
DOI:10.1016/j.tetlet.2013.07.008
摘要
An extension of the method for the regioselective introduction of nitrogen-containing heterocycles at the 1,5-phenolic positions of p-tert-butylcalix[8]arene previously described for 2,6-bis(chloromethyl)pyridine allowed the use of 2,9-bis(bromomethyl)-1,10-phenanthroline as a selective 1,5-dialkylating agent. The 1,5-dimethylpyridine derivative was previously characterized as a relatively rigid dicesium complex [1(4H)2−·2Cs+], its metal-free counterpart 1(6H) is herein described as a fluxional species in solution, as evidenced by VT–NMR and theoretical studies. The 1,5-[2,9-bis(methylene)-1,10-phenanthroline]-p-tert-butylcalix[8]arene analogue 2(6H) was characterized spectroscopically in solution as a relatively rigid cone conformer at 390 K. The identity of both metal-free 1(6H) and the monocesium complex [2(5H)−·Cs+] was established in the solid state by X-ray crystallography, confirming the 1,5-substitution of the latter. The conformational behavior of 1(6H) and 2(6H) in solution is described in terms of the enthalpic and entropic contributions by semiempirical methods.
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