Donor-Acceptor Tribenzotriquinacene-Based Molecular Wizard Hats Bearing Three ortho-Benzoquinone Units.

Two π-extended bay-bridged tribenzotriquinacenes ("TBTQ wizard hats") 12 and 16 bearing three mutually conjugated, alternating veratrole-type and ortho-benzoquinone units were synthesized. The electronic properties of these complementarily arranged, nonplanar push-pull systems are affected by the fusion with the rigid, C3 -symmetric TBTQ core to a different extent, as revealed by X-ray structural analysis, UV-vis spectroscopy and cyclovoltammetry. The combination of three quinone units within the original TBTQ core and three veratrole-type bay bridging units in 12 gives rise to a more efficiently π-conjugated chromophore, as reflected by the shallower shape of wizard hat and its absorption in the visible up to 750 nm in comparison to 16. Congener 12 contains an aromatic 18-π electron system in contrast to the cross-conjugated analog 16. X-ray structure analysis of the precursor dodecaether 15 revealed the formation of a cage-like supramolecular dimer, in which the peripheral dioxane-type ether groups interlace by twelve noncovalent C-H⋅⋅⋅⋅⋅O bonds.

π-Extension of the Tribenzotriquinacene Framework: Efficient Vinylene and Arylene Bay Bridging Based on a New C3 -Symmetric Key Derivative.

1,5,9-Tribromo-2,3,6,7,10,11-hexamethoxy-4b1 -methyltribenzotriquinacene, a C3 -symmetric TBTQ derivative, can be prepared conveniently and with high regioselectivity from readily available starting materials. It is a versatile key compound for the synthesis of other chiral 1,5,9-trifunctionalized TBTQ derivatives and π-extended congeners in which the bays of the TBTQ skeleton are bridged by vinylene and 1,2-arylene units. X-ray crystal structure analysis and UV-vis spectroscopy show that vinylene bay-bridging enables better π-conjugation with the arene rings of the TBTQ core than 1,2-arylene bay-bridging does.