Search

A preliminary report detailing the successful realization of a two-stage covalent connection strategy in a model system is presented. A model 1-naphthoic acid bearing a peri-positioned cinnamic acid residue crystallizes as a closed H-bonded dimer. The irradiation of the crystalline solid produces an alpha-truxillate-type cyclobutane photodimer in quantitative yield. This model shows the feasibility of designing a covalent molecular connector whose orientation is encoded by its H-bonding pattern.

The complete 'minimum energy path' of the low-lying region of the conical interactions space reaching from the closed to the open ring side is described. The model has shown that even though the van der Lugt and Oosterhoff concept has predicted the formation of an avoided crossing along the excited state minimum energy path ([S.sub.1]-IRC-MEP), it has provided an incomplete description of the decay process to the ground state.

Coronene is proposed to be 'superaromatic', but energetic, geometeric, and magnetic criteria of global and local aromaticity fail to support his proposal. However, [7,5,7,5,7,5]-isocoronene, which is a valence isomer, qualifies as superaromatic on the magnetic criterion, as verified by the excellent agreement with anisotropy and exaltation of magnetic susceptibility, while the energetic criterion shows that isocoronene is destabilized with respect to coronene.