Tetrathiafulvalene and π-extended tetrathiafulvalene pillar[5]arene conjugates: synthesis, electrochemistry and host-guest properties

Pillar[5]arene derivatives decorated with ten peripheral TTF subunits have been efficiently prepared from a decabrominated pillar[5]arene building block and appropriate TTF-thiolate nucleophiles. While the preparation of related systems with peripheral exTTF subunits could not be achieved under the same conditions, a fully substituted pillar[5]arene exTTTF conjugate has been prepared from a clickable pillar[5]arene derivative and an exTTF derivative bearing a terminal alkyne function. Electrochemistry investigations have revealed substantial electronic interactions between the TTF subunits in the conjugates. The peripheral TTF moieties are indeed confined in a restricted space and thus forced to interact. In contrast, no electronic interactions could be detected for the exTTF-containing system. Finally, binding studies have shown all the conjugates are capable of forming host-guest complexes with 1,6-dicyanohexane and a methanofullerene bearing a cyanoalkane moiety.

Automated summary

Pillar[5]arene derivatives with peripheral TTF subunits were efficiently synthesized using a decabrominated pillar[5]arene building block and appropriate TTF-thiolate nucleophiles. A fully substituted pillar[5]arene exTTTF conjugate was prepared from a clickable pillar[5]arene derivative and an exTTF derivative with a terminal alkyne function. Electrochemistry studies showed significant electronic interactions between the TTF subunits in the conjugates, while no interactions were detected in the exTTF-containing system. Binding studies demonstrated the capability of all the conjugates to form host-guest complexes with 1,6-dicyanohexane and a methanofullerene bearing a cyanoalkane moiety.