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Abstract
The interaction of tBu-calix[8]arene with C60 and C70 in the 1:1 and 1:2 models have been investigated by means of molecular dynamics and molecular mechanics (CVFF91 force field) calculations. The results reveal that one C60 molecule can be encapsulated in the cavity of the calixarene which adopts a conformation with six phenyl groups oriented upward and the other two (1 and 5) outward. The relatively weak bonded 1:1 C60-calixarene system is a result of attractive π…H(C-tBu. C-methylene) and repulsive π…π interactions. C70, more voluminous than C60 can not be accommodated in the cavity of the calixarcnc and forces it to a relatively opened conformation where the number of atractive interactions is less than in the C60-calixarene system. This conformation allows however the interaction with a second molecule and thus 1:2 adducts are formed. Thus, if proper substituents are on the calixarene and the fullerene size permite the encapsulation, 1:1 complexes are obtainable while if the fullerene size is larger than the cavity of the calixarene can cope with, only the 1:2 adducts can be separated.
1On leave of absence from Facultatea de Chimie, Universitatea Babes-Bolyai, RO-3400 Cluj-Napoca, Romania
Notes
1On leave of absence from Facultatea de Chimie, Universitatea Babes-Bolyai, RO-3400 Cluj-Napoca, Romania
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Among another sources, the coordinates of some common fullerenes can be accesed from by ftp from infomeister.osc.edu under /pub/data/chemistry/fullerenes directory.
Discover is comercially available from Biosym/MSI Co., California USA.