Pyrene cyclophanes

Even cyclophanes containing large aromatic units such as pyrene, anthracene, or benzophenanthrene units or partially hydrogenated annulated systems can easily be desulfurized via sulfone pyrolysis, as Staab et al. have shown in a series of works on such compounds [49 53],... 

Carbocations can be generated by the protonation of unsaturated hydrocarbons such as alkenes and cycloalkenes [49,52], cyclopentadienes [57], benzenes and naphthalenes (Eq. 24) [58], pyrenes and cyclophanes [59], unsaturated heterocycles [60], and their derivatives with carbon-heteroatom multiple bonds [2], including carbonyl and nitrile compounds and diazoalkanes [61]. 

In the case of the [2.2]- nerradical cations couple in 90% yield to give the tetrahydropyrene derivative XXVI [Eq. (16)] [146]. XXVI can be further oxidized to a pyrene [147]. [2.2]-Me a-cyclophanes with other substituents than methoxy—for example, with CH3, Br, CN, or NO2—can also be cyclized [148]. 

T. Z. M. Denti, W. F. van Gunsteren, and F. Diederich,/. Am. Chem. Soc., 118,6044 (1996). Computer Simulations of the Solvent Dependence of Apolar Association Strength Gibbs Free Energy Calculations on a Cyclophane-Pyrene Complex in Water and Chloroform. 

Fig. 5 Effect of solvent polarity on complex stability between pyrene and cyclophane host. View this art in color at www.dekker.com.)...

Polycyclic aromatic hydrocarbons can be bent by bridging in a similar fashion. Two recent examples of such [n]cyclophanes are azulenophane 116 [77] and 1,8-dioxa[8](2,7)pyrenophane 117 [78]. X-ray structure analysis revealed an angle of 3.7° between the azulene ring planes, whereas the pyrene moiety is bent by nearly 90°. 

Some other arene-antimony halide complexes have been structurally characterized all have intermolecular secondary Sb - -X interactions and supramolecular self-organization. Examples are naphthalene-2SbCl3 [414], phenanthrene-2SbCl3 [415], pyrene-2SbBr3 [416], and [(SbCl3)2(//- / -[2 ](l,4)cyclophane].v-0,5C6H6 [417], In the naphthalene complex [414] pairs of SbCl3 molecules are interconnected in planar stacks, with shorter primary bonds (axial Sb-Cl 2.367 A, equatorial Sb-Cl 2.347 A) and intermolecular distances Sb- -Cl 3.581-3.832 A. 

The second group is the cyclophanes of pyrene, where a planar system is forced to bend by linking both ends of the pyrene with an alkane chain. This highly strained curved group represents a compromise between strain and conjugation, and the nature of these systems aromaticity is of great interest. 

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