**3. Conclusion**

be high, since a large number of new C─C bonds that need to be formed necessitate the introduction of a big number of promoter groups. Moreover, the radical nature of the conden-

Although the FVP approach has been proven to be very prolific for the synthesis of small non-planar PAHs, the high-yield synthesis of large bowls and isomerically pure fullerenes has remained challenging. Recently, an efficient intramolecular fluorine-promoted ring closure in benzo[c]phenanthrenes under FVP conditions via HF elimination has been reported [46]. It has been shown that HF elimination is a synchronous process leading directly to the C─C bond formation without any intermediates, thus producing no side products [46]. The small size and low molecular weight of fluorine, as well as high thermostability of the C─F bond make fluorine a perfect activating group for the rational synthesis of fullerene by zipping approach. The feasibility of the approach has been demonstrated on the successful synthesis of C60 fullerene from the respective fluorinated precursor which was effectively folded into the fullerene under laser ionization. The respective 15-fold cyclization was realized in a domino fashion via consecutive HF elimination without observation of side reactions or undesired fragmentations [47]. As it is shown in **Figure 11**, the precursor molecule undergoes highly selective HF loss (with simultaneous C─C bond formation) leading to the open-cage which

sation could drastically affect the selectivity of the process.

20 Fullerenes and Relative Materials - Properties and Applications

**Figure 11.** Mass spectrum of the C60 fullerene precursor (C60H21F9

example of benzo[c]phenanthrene model.

showing an effective domino-like HF elimination yielding C60 fullerene via 15 selective C─C bond formation steps. The mechanism of single cyclodehydrofluorination involving a four-centered transition state is shown in the insert on the

) obtained under laser ablation (negative-ion mode)

The zipping strategy had been proved to be prolific for the rational synthesis of the fullerene fragments and the fullerene cages. The progress in this field shows the general possibility to fabricate elusive fullerenes in a fully controllable manner. Production of these unique materials in isomer-pure form in macroscopic amounts does no longer appear elusive, and there is promising prospect that such compounds will become available in the near future. Since there are virtually no limiting factors, there are no principle obstacles standing against extending the zipping approach to highly interesting related carbon-based architectures.
