RESUMO
A novel series of syn- and anti-ladder-type anilido-pyridine boron difluorides (APBDs) were synthesized by stepwise incorporation of boron into laddered ligands. The boron coordination-locked strategy endows the ladder-type APBDs with a stiff conformation, which results in a substantial bathochromic shift of their absorption spectra and a narrowed HOMO-LUMO energy gap, reinforcing the compounds for potential applications in organic electronics.
RESUMO
A series of doubly ß-to-ß 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 ß,ß'-diboryl Zn(II) porphyrin 1 with different bridges provided the doubly ß-to-ß 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.