Molecular beads

Formation of molecular necklaces [n]MN (n=4-7) has taken on a new 2+2 approach in which pseudorotaxanes containing two molecular beads, e.g. cucurbituril, are treated with the connective metal centers to afford the desired 25<99ACIE638>. 

Nucleosome. A complex of DNA and an octamer of histone proteins in which a small stretch of the duplex is wrapped around a molecular bead of histone. 

Like a molecular bead, cucurbituril can be threaded with a linear diammonium ion to form an inclusion complex [Fig. 20.4.8(b)]. This is stabilized by the fact that each protonated amino N atom forms hydrogen bonds to three of the... 

Some of our recent work on the construction of interlocked structures is described in this short review. In the design of these structures, the barrel-shaped molecule cucurbituril is used as a molecular bead and metal ions or metal complexes are used as glue or angle connectors . The examples given here demonstrate the efficiency and control in the self assembly of highly organized supramolecular species. 

Having synthesized the simple rotaxanes using cucurbituril as a molecular bead we turned our attention to polyrotaxanes. Polyrotaxanes have been synthesized by threading molecular beads , particularly cyclodextrins, with organic polymers [19-21, 35], Typical examples are the ones prepared by Harada et al. [19] and Wenz et al. 

In this review, I describe our efforts to construct interlocked structures such as rotaxanes, polyrotaxanes and molecular necklaces incorporating cucurbituril as a molecular bead by utilizing the principles of self-assembly and coordination chemistry. A key to the success of this synthesis is the high affinity of cucurbituril toward alkyl diammonium ions, which allows formation of a stable pseudorotaxane... 

Known examples involving OD motifs, i.e. molecular beads (cucurbituril molecules), threaded by coordination polymers of different topology have been described by Kim and coworkers [80],... 

An interesting work by Kim showed that the periphery of the dendrimers can be reversibly manipulated through noncovalent interactions (40). They used Cucurbituril as the molecular bead that encapsulates the amino butane peripheral units (Fig. 11). The pseudorotaxane-terminated dendrimers not only gave a... 

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