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Coordination-driven face-directed self-assembly of trigonal prisms. Face-based conformational chirality
被引:0
|作者:
Caskey, Douglas C.
[3
]
Yamamoto, Takuya
[1
]
Addicott, Chris
[1
]
Shoemaker, Richard K.
[3
]
Vacek, Jaroslav
[3
,4
]
Hawkridge, Adam M.
[2
]
Muddiman, David C.
[2
]
Kottas, Gregg S.
[3
]
Michl, Josef
[3
,4
]
Stang, Peter J.
[1
]
机构:
[1] Department of Chemistry, University of Utah, 315 South 1400 East, Salt Lake City, UT 84112, United States
[2] W. M. Keck FT-ICR Mass Spectrometry Laboratory, Department of Chemistry, North Carolina State University, Raleigh, NC 27695, United States
[3] Department of Chemistry and Biochemistry, University of Colorado, Boulder, CO 80309-0215, United States
[4] Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, 166 10 Prague 6, Czech Republic
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关键词:
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 ΔH‡ of ∼12 kcal/mol and activation entropy ΔS‡ of ∼-15 cal/molK for the edge interconversion process;
compatible with pyridine rotation around the Pt-N bond. For 3c;
this behavior is observed only up to ∼318 K. At higher temperatures;
the Eyring plot is again linear but follows a very different straight line;
with a ΔH‡ of ∼35 kcal/mol and ΔS‡ of ∼60 cal/molK. This highly unusual result is further investigated and discussed in the following companion paper. © 2008 American Chemical Society;
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页码:7620 / 7628
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