Stacked benzene

FIGURE 16. Various structures of SU, fullerene (112, Ih)137 stacked naphthalene (113, >2h)137> stacked benzene (114, C2v)137, fullerenes (115, C2v)138 and (166, C2h)140- Reproduced from Reference 137, Copyright (1993) by courtesy of Marcel Dekker Inc. and from References 138 and 140, Copyright (1994) with kind permission of Elsevier Science-NL, Sara Burgehartstraat 25, 1055 KV Amsterdam, The Netherlands... 

In recent years further novel classes of compounds were added to cyclophane chemistry. The multilayeredphanesiS derived from [2.2]paracyclophane contain coaxially stacked benzene rings connected by ethano bridges para to one another. The first members of this series were described in 196416. Quadruple layered phane hydrocarbons 3 and 4 reveal in their UV-spectra long range electronic effects penetrating several arene units. 

The doubly clamped helix 148, designed by Vogtle et al., which also contains stacked benzene rings was accessible by sulfone pyrolysis from 147 in 37% yield [26]. 

Scattering Phenomena.—A review has appeared of the scattering of depolarized light by simple fluids.437 Pre-resonance Raman spectra of NH3, CH8NH2, form-amide, cw-dichloroethylene, propargyl alcohol, and pyrazine 438 resonance Raman scatter of I2 in solution and in inert matrices 439 time-resolved resonance fluorescence and resonance Raman 440 and stimulated resonance Raman scattering 441 pseudo-Raman spectra in stacked benzene molecules 442 and birefringence in CS2 443 have been the subjects of recent reports. 

All members in the series of [2 ]cyclophanes [3] up to the sixfold-clamped superphane [4] are known today. Among the [n]paracyclophanes [5] bridging with a pentamethylene chain has established an end point so far and in the case of the syntheses of multilayered [2 J cyclophanes [6] a limit of six stacked benzene rings has been achieved. 

To explore this vital issue of cooperativity which reflects the nonadditive behavior of noncovalent interactions we have considered different model systems. In the first case we seek to check for presence of cooperativity among cation-n and hydrogen bonding [122] and cation-jt and jt-jt interactions [123]. In the second case we quantify cooperativity in systems with noncovalent interactions other than cation-jt interaction, for example in hydrogen bonded clusters of water, formamide and acetamide [110], clusters of jt-jt stacked benzene [124] etc. (Fig. 18.6). 

The placement of conjugated arms on a [2.2]paracyclophane scaffold has provided a large number of conjugated polymers and oligomers in which the stacked benzene rings of the cyclophane are part of the conjugated segments (Fig. 10). In the... 

---