Template-Assisted Synthesis of a Polycarbazole Macrocycle

Significance

A fully conjugated macrocycle, comprised of twelve 2,7-carbazole units was synthesized via a template-assisted macrocyclization approach. Esterification of meso-tetraphenylporphyrin template 2 with four equivalents of tricarbazole 1 followed by nickel-mediated Yamamoto coupling and hydrolytic cleavage of the ester groups provided target polycarbazole macrocycle 3. The conguated cyclic π-system of 3 was evidenced by AFM measurements and STM investigations. X-Ray scattering experiments indicated that macrocycle 3 self-assembled into columnar structures. The reported polycarbazole macrocycle represents one of few examples possessing an extended π-conjugation.