Catenanes olympiadane

Numerous interlocked structures [25], including a [5]catenane (olympiadane) [26], were built using the self-organization of crown ether derivatives containing... 

Figure 8. Examples of rotaxanes and catenanes with peculiar structures, (a) A branched [4)rotaxane [26a] (b) a [5]catenane (olympiadane) [26c] (c) a rotocatenane [28] (d) a [2]catenane with three rings [27d].

Stoddart and coworkers [112-115] cyclized bis(bipyridyl)s in the presence of crown ethers to obtain a [2]catenane at a yield of 70%. It is illustrated in Fig. 37. The high yield can be attributed to the 7i-donor-acceptor interaction between the ring and the axle. It was shown that one of the two intercrossed rings moves around the other. The group of Stoddart [116-118] reported [3-5] catenanes (see Fig. 38 for [3]catenane). The [5]catenane of Stoddart et al. [118] was named olympiadane , because it resembles the symbol logo of International Olympic Games, as seen in Fig. 39. 

Two outstanding forerunners of high molecular-weight polycatenanes are the [5]catenane 30, also named olympiadane, and the [7]catenanes 31 reported by Stoddart and coworkers (Scheme 10) [46, 49]. The synthetic strategy leading to... 

Figure 10.61 X-ray crystal structure of the [7] catenane analogue of olympiadane.64 See plate section for colour version of this image.

Like knots, links may be prime or composite. The Hopf and Borromean links are examples of prime links because they cannot be divided (factored) into smaller, nontrivial links. Figure 30(a) is the minimal diagram of a composite link that is the abstract representative of some [3]catenanes, one of which is depicted in Figure 30(b).103b That the three-component link is a composite link is shown by the fact that a plane perpendicular to the plane of projection (dashed line) and pierced in exactly two points cuts the link in half If the open ends on both sides of the plane are now joined to form closed curves, two Hopf links result. In analogy to composite knots, the three-component link in Figure 30(a) is denoted by 2 2j, and the five-component composite link that represents olympiadane by 2 2 2 2. ... 

A representative selection of [2]catenanes synthesized by this route is given in Table 10.1[14b, 15a, 16]. It is remarkable to note that the first [2]catenane synthesized (entry 2, Table 10.1) could be isolated in 74% yield [14,16], The final entry in the table is an example of an expanded version of the tetracationic macrocycle which incorporates a biphenylene spacer between the paraquat residues and can accommodate two n-stacked aryl rings within its cavity. The reaction results in the isolation of the [3]catenane product in 25% yield with very little (2%) [2]catenane isolated [16p]. A spectacular demonstration of the power of this approach by Stoddart and coworkers was the iterative synthesis of a [5] catenane which the authors dubbed Olympiadane after its resemblance to the Olympic rings [17]. 

Likewise, three-dimensional renderings of MIMs remind us instantly of some of the ordinary objects we encounter in our everyday lives (see Sect. 2.3). Take olympiadane [82], for example (Fig. 13), with its five interlocked rings unmistakably sharing the same topology as the Olympic logo Most catenanes bear resemblance at least to the links of a chain, as their name implies. Regardless of their resemblance to familiar objects, hundreds of beautiful crystal structures of MIMs have been produced since their debut in 1985, when Sauvage [83] published the first solid-state structure of a [2]catenane (Fig. 14a). It would be impossible to do justice to all of the beauty contained in the databank of solid-state mechanically interlocked structures. In Fig. 14 we simply present a few examples that we find noteworthy [84—88]. See Fig. 23 in Sect. 4.2 for more beautiful crystal structures of some particularly novel MIMs. 

Stoddart and co-workers transferred the strategy of template-directed synthesis to the formation of the first molecular system consisting of five interlocked rings in a linear array (Structure 51). They suggested that this [5]catenane should be called olympiadane [64]. Recently they reported the self-assembly of a new type of rotaxane, in which three side chains are linked directly to a single central core, producing a dendritic-type structure [65]. 

In 2000. Vogtle et al. found another route toward [ ]catenanes—new tetralactarn and octalactam macrocycles were used to obtain [njcatenanes (Scheme 5) with up to five rings. The largest of these is the first amide-type olympiadane, which, however, could not be isolated. The octalactam macrocycle served as a ditopic host permitting the threading of two other macrocycles. 

In 1994 J. E Stoddart and co-workers, then at the University of Birmingham (England), achieved a remarkable synthesis of a catenane containing a linear array of five interlocked rings. Because the rings are interlocked in the same way as those of the Olympic symbol, they named the compound olympiadane. 

---