Strongly underestimated dispersion energy in cryptophanes and their complexes
Strongly underestimated dispersion energy in cryptophanes and their complexes
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DOI：
10.1038/ncomms4542
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发表时间：
2014-03-01
影响因子：
16.6
通讯作者：
Bandmann, Heinz
中科院分区：
文献类型：
--
作者：
Haberhauer, Gebhard;Woitschetzki, Sascha;Bandmann, Heinz
Cryptophanes是一类典型的有机主体分子，由三个脂肪族连接基团连接的两个碗状环三藜芦烯亚基组成，通过伦敦力可逆地与中性小客体化合物结合。这些络合物的结合常数通常在四氯乙烷中测量，并且在10（2）-10（3）M-1的范围内。在这里，我们表明，四氯乙烷是相反的科学共识，封闭的cryptophane-E腔。通过NMR光谱，我们表明，CHCl3@cryptophane-E的结合常数是在较大的溶剂中的两个数量级高于以前测量的。从头计算结果表明，有吸引力的色散能是负责高的结合常数和形成的内爆cryptophanes，这似乎是更稳定的比cryptophanes与空腔。
Cryptophanes, composed of two bowl-shaped cyclotriveratrylene subunits linked by three aliphatic linker groups, are prototypal organic host molecules which bind reversibly neutral small guest compounds via London forces. The binding constants for these complexes are usually measured in tetrachloroethane and are in the range of 10(2)-10(3) M-1. Here we show that tetrachloroethane is-in contrast to the scientific consensus-enclosed by the cryptophane-E cavity. By means of NMR spectroscopy we show that the binding constant for CHCl3@cryptophane-E is in larger solvents two orders of magnitudes higher than the one measured before. Ab initio calculations reveal that attractive dispersion energy is responsible for high binding constants and for the formation of imploded cryptophanes which seem to be more stable than cryptophanes with empty cavities.