A chiral spherical molecular assembly held together by 60 hydrogen bonds

• Published in: Nature (London) 1997-10, Vol.389 (6650), p.469-472
• Main Authors: Atwood, Jerry L, MacGillivray, Leonard R
• Format: Article
• Language: English
• Subjects: Atomic and molecular physics; Chemistry; Effects of atomic and molecular interactions on electronic structure; Electronic structure of atoms, molecules and their ions: theory; Exact sciences and technology; Humanities and Social Sciences; Hydrogen; letter; Molecules; multidisciplinary; Physics; Science; Science (multidisciplinary); Scientific imaging; Topology
• ISSN: 0028-0836; 1476-4687
• DOI: 10.1038/38985

Spontaneous self-assembly processes that lead to discretespherical molecular structures are common in nature. Sphericalviruses (such ashepatitis B) and fullerenes are well-known examples inwhich non-covalent and covalent forces,respectively, direct the assembly of smaller subunits intolarger superstructures. A common feature of theseshell-like architectures is their ability to encapsulateneutral and/or charged guests whose size, shape and chemicalexteriors complement those of the host's innersurface,. Their interiors can often beregarded as a new phase of matter, capable of controlling the flowof reactants, transients and products, and of catalysingreactions of both chemical and biological relevance. Suchproperties have inspired the recent emergence ofmonomolecular and supramolecular dimeric molecularcapsules,, many of which have been basedon the head-to-head alignment of bowl-shapedpolyaromatic macrocycles such as calix[4]arenes,,. But true structural mimicry offrameworks akin to viruses and fullerenes, which are based onthe self-assembly of n > 3 subunits,and where surface curvature is supplied by edge sharing of regularpolygons, has remained elusive. Here we present anexample of such a system: a chiral spherical molecular assemblyheld together by 60 hydrogen bonds (1) (Fig. 1). We demonstrate the ability of 1, which consists of six calix[4]resorcinarenes 2 and eight water molecules, to self-assemble and maintain its structure in apolar media and to encapsulate guest species within a well-defined cavity that possesses an internal volume of about 1,375 Å3. Single crystal X-ray analysis shows that its topology resembles that of a spherical virus and conforms to the structure of a snub cube, one of the 13 Archimedean solids.