Extended 7t systems

Some additional derivatives containing extended 7t-systems in place of the benzene nucleus are naphthalene, anthracene (2,3-Ac) and phenanthrene (9,10-Phc). They also belong to the phthalocyanine family. For the naphthalene system two types of macrocyclcs, the 1,2-naph-thalocyanine (1,2-Nc) and the 2,3-naphthalocyanine (2,3-Nc), are known. 

Simple olefins do not react with eaq at an appreciable rate, but compounds with an extended 7t-system such as butadiene can also accommodate an additional electron (k = 8 x 109 dm3 mol-1 s 1 Hart et al. 1964). However, as in the case of benzene, the rate is often below diffusion controlled [reaction (23) k = 7.2 x 106 dm3 mol 1 s 1 (Gordon et al. 1977) in THF, the reaction of the solvated electron with benzene is even reversible (Marasas et al. 2003)], and the resulting radical anion is rapidly protonated by water [reaction (24)]. 

In the field of hydrocarbons, radical cations of extended 7t systems tend to form 7t dimers under appropriate reaction conditions. This was established for classical aromatics such as naphthalene or anthracene. In cyclophanes, the geometric restrictions force the aromatic constituents to interact through space. 

When interpreting the solution and solid-state ENDOR spectra of radical anions of oligophenylenevinylenes it is not perfectly clear to what extent the observed localization of the charge in a particular subunit can be attributed to counterion induced polarization or to structural changes such as a twisted conformation. It is therefore important to include rigid and planar structures with extended 7t-systems for which the ries of peri-fused naphthalenes 44 appears as a suitable example [120, 121]. Such two-dimensional ladder-type... 

SI 4.1 (a) The extended 7t system for each of the planes of graphite results in a band of n orbitals. The band is half filled... 

Both the molecular exciton model and the extended dipole model can be used to calculate one of the parameters—i.e, the distance of the chromophores, the inclination angle, or the number of aggregated chromophores—if the other parameters are known. However, in most LBK systems under consideration, it is the case that none of the parameters is known exactly. Nevertheless, in some cases well-justified assumptions can be made, and an estimation of, e.g., the inclination angle is possible. - In any case, the spectral shift observed in ordered arrangements of extended 7t-systems can be related to the aggregation and orientation of the chromophores. A very... 

Kovacevic, B., Maksic, Z.B. and Vianello, R. (2001) The proton affinity of some extended 7t-systems involving guanidine and cyclopropenimine subunits. Journal of the Chemical Society -Perkin Transactions 2, 886-891. 

Admittedly, covalent functionalization may strongly affect the extended 7t-system, dramatically changing the electronic properties of SWCNTs. Therefore, in order to maintain the contact between the dcmor and the acceptor and, at the same time, to preserve the electronic structure of SWCNTs, polymer wrapping cmistitutes an eligible alternative. Interestingly, with this idea, Guldi et al. proposed the functionalization... 

Zimmerman, H.E. and Earners, P.H., Photochemistry of some extended 7t-systems type A and aryl rearrangements of systems with extended conjugation related to cyclohexadienones and cyclohex-enones. Mechanistic and exploratory organic photochemistry, /. Org. Chem., 54, 5788,1989. 

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