A Tetra-Porphyrin Host Exhibiting Interannular Cooperativity.,Chemistry - A European Journal

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A Tetra-Porphyrin Host Exhibiting Interannular Cooperativity.
Chemistry - A European Journal ( IF 3.9 ) Pub Date : 2019-09-10 , DOI: 10.1002/chem.201903636
Rhys B Murphy _{1,

2} , Duc-Truc Pham ₃ , Martin R Johnston ₁

Affiliation

Recently identified as another form of cooperativity, interannular cooperativity is rarely observed in supramolecular chemistry. A tetra-porphyrin molecular tweezer with two bis-porphyrin binding sites is reported that exhibits archetypal interannular cooperativity when complexing 1,4-diazabicyclo[2.2.2]octane (DABCO). The UV/Vis titration data best supported a 1:2 plus 2:2 plus 1:4 complexation model (host:guest), giving K12 =6.32×1013 m-2 , K22 =3.04×1020 m-3 , and K14 =1.92×1016 m-4 in CHCl3 . The NMR titration data supported the formation of two sandwich species, including tetra-porphyrin⋅(DABCO)2 as the major species, although there are speciation differences between UV/Vis and NMR concentrations. Using statistical analysis, interannular cooperativity (γ) for tetra-porphyrin⋅(DABCO)2 was determined to be negative (γ=2.41×10-3 ), which may be explained by DABCO being too small to be optimally bound simultaneously at both bis-porphyrin binding sites.

中文翻译：

四环卟啉宿主表现环间合作。

最近被鉴定为另一种形式的合作性，超分子化学中很少观察到环间合作性。据报道，具有两个双卟啉结合位点的四卟啉分子钳在复合1,4-二氮杂双环[2.2.2]辛烷（DABCO）时表现出原型环间协同性。UV / Vis滴定数据最好地支持1：2加2：2加1：4络合模型（宿主：客体），得出K12 = 6.32×1013 m-2，K22 = 3.04×1020 m-3，而K14 =在CHCl 3中为1.92×1016m-4。NMR滴定数据支持形成两个夹心物质，包括四卟啉·（DABCO）2作为主要物质，尽管UV / Vis和NMR浓度之间存在形态差异。使用统计分析确定四卟啉·（DABCO）2的环间协作性（γ）为负（γ= 2.41×10-3），

更新日期：2019-09-10

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