Synthesis and Photophysical Properties of Doubly β-to-β Bridged Cyclic ZnIIPorphyrin Arrays

Abstract A series of doubly β‐to‐β bridged cyclic Zn II porphyrin arrays were prepared by a stepwise Suzuki–Miyaura coupling reaction of borylated Zn II porphyrin with different bridge groups. The coupling of the building block of β,β′‐diboryl Zn II porphyrin 1 with different bridges provided the doubly β‐to‐β carbazole‐bridged Zn II porphyrin array 3 , the fluorene‐bridged Zn II porphyrin array 5 , the fluorenone‐bridged Zn II porphyrin array 7 , and the three‐carbazole‐bridged Zn II porphyrin ring 8 . The structural assignment of 3 was confirmed by the X‐ray diffraction analysis, which revealed a highly symmetrical and remarkably bent syn‐form structure. The incorporation of bridge units with different electronic effects results in different photophysical properties of the cyclic Zn II porphyrin arrays. Comprehensive photophysical studies demonstrate that the electron‐withdrawing bridge fluorenone has the largest electronic interaction with the Zn II porphyrin unit among the series, thus resulting in the highest two‐photon absorption cross‐section values (σ (2) ) of 6570±60 GM for 7 . The present work provides a new strategy for developing porphyrin‐based optical materials.