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首页> 外文期刊>Chemistry: A European journal >The role of chirality in directing the formation of cup-shaped porphyrins and the coordination characteristics of such hosts
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The role of chirality in directing the formation of cup-shaped porphyrins and the coordination characteristics of such hosts

机译：手性在引导杯状卟啉形成的作用以及这些宿主的配位特征

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Cup-shaped porphyrin 1a has four norbornane rings for encircling space and this type of host could be of interest in supramolecular and catalytic chemistry. We used ~1H NMR spectroscopy to investigate the acid-catalyzed (pTsOH in CHCl_3 and TFA in CH_3CN) condensation of racemic, enantioenriched (80-85% enantiomeric excess (ee)), and enantiopure (99% ee) pyrromethanecarbinol 7 into 1a. We found that the oligomerization of racemic 7_(rac) would give 1a-d in the ratio different from the statistical one, though a minuscule quantity of 1a (<5%) formed. The oligomerization of enantioenriched 7 (80-85% ee), however, led to the formation of greater amounts of 1a (31-47%) along with other stereoisomers 1b-d. Importantly, pTsOH catalyzed the conversion of enantiopure 7 (99% ee) into 1a (>95% diastereomeric excess (de), 25% overall yield) in CHCl_3 although prolonged reaction times or greater concentration of the catalytic acid gave rise to 1b-d at the expense of 1a. The metallation of 1a with Zn(OAc) _2 led to the formation of Zn~(II)-1a and we used computational (DFT: RI-BP86/SV(P),TZVP) and experimental (~1H NMR spectroscopy) methods to study the partitioning of smaller N-methylimidazole 13 (94 ?3) and bigger 1,5-dicyclohexylimidazole 14 (268 ?3) between the inner and outer side of the host. We found that bigger 14 was mostly encapsulated (90%) inside Zn~(II)-1a at 298.0 K, whereas smaller 13 would equally partition between the two sides of the host. Furthermore, the out/in equilibrium was, in the case of 14-Zn~(II)-1a, favored by entropy (TΔS°_(out/in)=3.5±0.1 kcalmol ~(-1)) indicating that perhaps differential solvation of the coordinated ligand assisted the encapsulation.
机译：杯形卟啉1A具有四个用于环绕空间的降冰片烷环，并且这种类型的宿主可能对超分子和催化化学感兴趣。我们使用〜1H NMR光谱法研究外消旋，对苯丙胺（80-85％映体过量（EE））的酸催化（CHCL_3和TFA中的PTOH）缩合，并对映致（99％）吡咯甲烷丙烯酚7中的致映致氢（99％）。我们发现外消旋7_（RAC）的寡聚化将以不同于统计统计学的比率给出1A-D，但是形成的小曲线量为1A（<5％）。然而，对苯丙胺的7（80-85％）的寡聚化导致形成更大量的1A（31-47％）以及其他立体异构体1B-D。重要的是，PTSOH催化对映致7（99％）的转化为1A（> 95％非对映异构体过量（DE），虽然延长的反应时间或更高的催化酸浓度产生1B-D.以牺牲1a为代价。用Zn（OAC）_2的1A的金属导致形成Zn〜（II）-1A，我们使用计算（DFT：RI-BP86 / SV（P），TZVP）和实验（〜1H NMR光谱）方法。方法研究较小的N-甲基咪唑13（94→3）和较大的1,5-二环己酰胺14（268→3）在宿主的内侧和外侧之间的分配。我们发现更大的14在298.0 k处大多封装（90％）Zn〜（II）-1a内部，而较小的13将在主体的两侧同样分配。此外，在14- Zn〜（II）-1a的情况下，通过熵（Tδs°_（Out / In）= 3.5±0.1kcalmol〜（-1）），表明可能是差异的14- Zn〜（II）-1a的情况下配位配体的溶剂辅助封装。

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