Coordination-driven face-directed self-assembly of trigonal prisms. Face-based conformational chirality
Coordination-driven face-directed self-assembly of trigonal prisms. Face-based conformational chirality
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DOI：
10.1021/ja710715e
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发表时间：
2008-06-18
影响因子：
15
通讯作者：
Stang, Peter J.
中科院分区：
文献类型：
--
作者：
Caskey, Douglas C.;Yamamoto, Takuya;Stang, Peter J.
The coordination-driven self-assembly of four different trigonal prisms from 3 equiv of one of four different tetrapyridyl star connectors and 6 equiv of a platinum linker dication in nitromethane is presented. This face-directed approach affords high yields without template assistance. The prisms have been characterized by multinuclear and DOSY NMR and dual ESI-FT-ICR mass spectrometry. The use of a conformationally chiral star connector leads to a conformationally chiral prism when connector arm ends attached to a vertex have a strongly correlated twist sense and chirality is communicated across polyhedral faces, edges, and vertices. Molecular mechanics results suggest that in the smallest prism 3d collective effects dominate and the all-P and all-M conformers are strongly favored. NMR data prove that the two edges of the pyridine rings in the triflate salts of 3a-3d are distinct. An Eyring plot of rates obtained from line-shape analysis and 1-D EXCHSY NMR yields an activation enthalpy Delta H-double dagger of similar to 12 kcal/mol and activation entropy Delta S-double dagger of similar to-15 cal/mol.K for the edge interconversion process, compatible with pyridine rotation around the Pt-N bond. For 3c, this behavior is observed only up to similar to 318 K. At higher temperatures, the Eyring plot is again linear but follows a very different straight line, with a Delta H-double dagger of similar to 35 kcal/mol and Delta S-double dagger of similar to 60 cal/mol.K. This highly unusual result is further investigated and discussed in the following companion paper.
