| Abstract
| - This paper introduces a concept that is referred to as cavity-directed synthesis by showing the selectiveoligomerization of trialkoxysilanes, RSi(OMe)3 (7), in self-assembled hollow compounds. Pd(II)-linkedcoordination hosts (cage, bowl, or tube) are found to strictly control the oligomerization of 7 (R = 2-naphthyl)in such a way that their optimal guests are produced in their cavities. Thus, within coordination tube 1, onemolecule of 7 is accommodated and subsequently hydrolyzed to give silanetriol RSi(OH)3 (4). Under ordinaryaqueous conditions, this reactive compound undergoes rapid polycondensation (so-called sol−gel condensation)leading to Si−O networks. Within the cavity of 1, however, 4 remains very stable and the polycondensationis completely suppressed. On the other hand, coordination bowl 2 and cage 3 give its dimers RSi(OH)2OSi(OH)2R (5) and cyclic trimers [RSi(OH)O]3 (6), respectively. X-ray crystallographic studies clearly show thatthe cavity size and the shape of 1, 2, and 3 nicely fit with those of 4, 5, and 6, respectively, demonstrating thatthe cavities strictly direct the oligomerizaion reaction of 7.
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