β‐to‐β 2,5‐Pyrrolylene‐Linked Cyclic Porphyrin Oligomers

Abstract

β-to-β 2,5-Pyrrolylene linked cyclic porphyrin oligomers have been synthesized by Suzuki-Miyaura coupling of 2,5-diborylpyrrole and 3,7-dibromoporphyrin. The cyclic porphyrin oligomers exhibit roughly coplanar structures, strong excitonic coupling, small electrochemical HOMO-LUMO gaps, and ultrafast excitation energy transfer between the neighboring porphyrins via the pyrrolylene bridge.

Benzene- and pyridine-incorporated octaphyrins with different coordination modes toward two PdII centers

“…Recently we explored various porphyrinoids by using Suzuki-Miyaura coupling. Reported examples include cyclic porphyrin rings, BODIPY-porphyrin hybrids, and earring porphyrins [24][25][26][27][28] . Despite of these studies, we thought that this coupling strategy could be applied to the synthesis of pyridine-incorporated expanded porphyrins.…”

Recent Advances in Heterocyclic Nanographenes and Other Polycyclic Heteroaromatic Compounds

“…A relatively high degree of coplanarity between subunits is displayed by 2,5-pyrrolylene-linked cyclic porphyrin dimers C34.1a , b and trimers C34.1d – c , obtained by Song et al via Suzuki–Miyaura coupling of 2,5-diborylpyrrole with appropriate 3,7-dibromoporphyrins ( Chart 34 ). 722 C34.1a adopted a bent geometry, in which the pyrrole nitrogens were pointing inward, whereas C34.1d showed a more coplanar triangular molecular shape with a reverse alignment of pyrrole bridges. Zinc complexes C34.1c and C34.1f were also prepared from the corresponding free base oligomers.…”

Synthesis and Functionalization of Porphyrins through Organometallic Methodologies

“…The group of Osuka reported the synthesis of 2,6-pyridylene-bridged β-to-β porphyrin nanorings including a “porphyrin nanobarrel” through the Suzuki–Miyaura cross-coupling reaction of Ni­(II) tetra­(6-bromopyridyl)­porphyrin 66.1 and Ni­(II) β- tetraborylporphyrin 18.3Ni . , The coupling reaction using Pd 2 dba 3 , PPh 3 , Cs 2 CO 3 , and CsF in a toluene/DMF mixed solvent afforded porphyrin nanobarrel 66.2 in 10% yield (Scheme ). This protocol worked effectively to afford various arylene- and heteroarylene-bridged cyclic oligoporphyrins, such as 2,5-thienylene-bridged cyclic porphyrins, , 2,6-pyridylene-bridged porphyrin nanorings, a 3,6-carbazolyl-bridged diporphyrin, pyrrole- and azobenzene-bridged porphyrin nanorings, , and a doubly bridged porphyrin-perylene-porphyrin triad . This protocol was further extended to the construction of directly meso –β doubly linked porphyrin ring 67.1 through the coupling of 22.1H with meso -dibromoporphyrin 52.1H . − This “Lego block” strategy furnished a variety of directly linked cyclic oligoporphyrins.…”

“…133,215 The coupling reaction using Pd 2 dba 3 , PPh 3 , Cs 2 CO 3 , and CsF in a toluene/ DMF mixed solvent afforded porphyrin nanobarrel 66.2 in 10% yield (Scheme 66). This protocol worked effectively to afford various arylene-and heteroarylene-bridged cyclic oligoporphyrins, such as 2,5-thienylene-bridged cyclic porphyrins, 216,217 2,6pyridylene-bridged porphyrin nanorings, 218 a 3,6-carbazolyl-bridged diporphyrin, 219 pyrrole-and azobenzene-bridged porphyrin nanorings, 220,221 and a doubly bridged porphyrinperylene-porphyrin triad. 222 This protocol was further extended to the construction of directly meso−β doubly linked porphyrin ring 67.1 through the coupling of 22.1H with mesodibromoporphyrin 52.1H.…”