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首页> 外文期刊>Chemistry: A European journal >Bis(oxofluorenediyl)oxacyclophanes:Synthesis,Crystal Structure and Complexation with Paraquat in the Gas Phase
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Bis(oxofluorenediyl)oxacyclophanes:Synthesis,Crystal Structure and Complexation with Paraquat in the Gas Phase

机译：双（氧氟芴基）氧杂环烷酮：气相中百草枯的合成，晶体结构和与百草枯的络合

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摘要

The first three representatives of the new family of oxacyclo-phanes incorporating two 2,7-dioxy-fluorenone fragments,connected by[-CH_2CH_2O-]m spacers(m = 2-4),have been synthesized.The yield of the smallest oxacyclophane(m = 2)is considerably higher with respect to the larger ones(m = 3 and m = 4),which are formed in comparable yields.Molecular modeling and NMR spectra analysis of the model compounds suggest that an essential difference in oxa-cyclophanes yields is caused by formation of quasi-cyclic intermediates,which are preorganized for macrocycli-zation owing to intramolecular n-jt stacking interactions between the fluo-renone units.The solid-state structures of these oxacyclophanes exhibit intra-and intermolecular it-it stacking interactions that dictate their rectangular shape in the fluorenone backbone and crystal packing of the molecules with the parallel or T-shape arrangement.The crystal packing in all cases is also sustained by weak C-H-O hydrogen bonds.FAB mass spectral analysis of mixtures of the larger oxacyclophanes(m=3 and m = 4)and a paraquat moiety revealed peaks corresponding to the loss of one and two PF6 coun-terions from the 1:1 complexes formed.However,no signals were observed for complexes of the paraquat moiety with the smaller oxacyclophane(m = 2).Computer molecular modeling of complexes revealed a pseudorotaxane-like incorporation of the paraquat unit,sandwiched within a macrocyclic cavity between the almost parallel-aligned fluorenone rings of the larger oxacyclophanes(m = 3 and m = 4).In contrast to this,only external complexes of the smallest oxacyclophane(m = 2)with a paraquat unit have been found in the energy window of 10 kcalmol"1.
机译：合成了新的草酸酯环家族的前三个代表，该家族引入了两个由[-CH_2CH_2O-] m间隔基（m = 2-4）连接的2,7-二氧芴酮片段。最小的草酸酯环的产量（m = 2）相对于较大的（m = 3和m = 4）而言要高得多，后者以可比较的产率形成。模型化合物的分子建模和NMR光谱分析表明，氧杂环烷存在本质上的区别产量是由准环状中间体的形成引起的，由于准氟中间体之间的分子内n-jt堆积相互作用，这些准环状中间体被预先组织为大环化反应。在芴酮主链中决定其矩形形状的分子之间的相互作用以及平行或T形排列的分子的晶体堆积。在所有情况下，晶体堆积还通过弱的CHO氢键维持.FAB质谱对较大的草环芳烃（m = 3和m = 4）和百草枯部分的混合物进行分析发现，峰对应于形成的1：1配合物损失了一个和两个PF6化合物，但是没有观察到任何信号配合物的计算机分子模型揭示了百草枯单元的拟轮烷状掺入，其夹在较大草酸酯基环己烯酮的几乎平行排列的芴酮环之间的大环腔内（m = 2）。与此相反，在10 kcalmol“ 1的能量窗口中，仅发现了最小的草并环磷酰胺（m = 2）和百草枯单元的外部络合物。

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