Expanded Azaporphyrins Consisting of Multiple BODIPY Units: Global Aromaticity and High Affinities Towards Alkali Metal Ions

Abstract

The one‐pot self‐coupling reaction of 3‐amino‐5‐bromo‐BODIPY 9 under Buchwald–Hartwig amination conditions gave nitrogen‐bridged cyclic BODIPY tetramer 10, pentamer 11, and hexamer 12. Oxidation of 10, 11, and 12 in the presence of alkali metal ions provided 13, 15, and 16, respectively, as the first examples of expanded azaporphyrins possessing more than six pyrrole rings. Curiously, the oxidation even in the absence of alkali metal ions gave the same complexes as a result of spontaneous complexation. 10–12 showed large association constants (104–106 M−1) with K+ and Na+, but the spontaneous complexations were not observed, indicating the extremely high affinities of 13–16 toward alkali metal ions, which can be ascribed to the multiple and effective ion–dipole interaction of the alkali metal ion with the negatively polarized F atoms of the BF2 walls surrounding the cavity. Importantly, 13, 14, and 15 show diatropic ring currents as a result of global aromaticity.

Mono- and bis-Pd(ii) complexes of N-confused dithiahexaphyrin(1.1.1.1.1.0) with the absorption and aromaticity modulated by Pd(ii) coordination, macrocycle contraction and ancillary ligands

“…For example, hexaphyrins may coordinate to either one or two metal ions within the two cavities, and the coordinated metal ions exhibit rich oxidation states. [31][32][33][34][35][36][37][38][39][40][41][42][43][44][45][46][47][48] In addition, the N-confused pyrrole unit may trigger interesting macrocycle transformations and thus further modulate the coordination behavior. [49][50][51][52][53][54][55] These metal complexes are promising for applications in various areas like catalytic, photoelectric and biomedical materials.…”

Cyclic Azobenzene‐BODIPY Hybrids

“…On the other hand, BODIPY's have been also extensively explored as functional chromophores in diverse applications [6] . Recently, cyclic BODIPY oligomers have also attracted considerable attention in light of their potentials such as light harvesting antenna, [7] molecular recognition hosts, [8] laser dye, [9] and novel expanded porphyrins with high affinities towards alkali metal ions [10] . Here we wish to report on the design, synthesis, structures and photophysical properties of the cyclic azobenzene‐BODIPY conjugated hybrids.…”

Linear Amine-Linked Oligo-BODIPYs: Convergent Access via Buchwald–Hartwig Coupling

“…7 Furthermore, cyclic amine-linked oligo-BODIPYs have already been synthesized in a one-pot reaction in 2022 by Song et al, utilizing Buchwald−Hartwig conditions (Figure 1A(c)). 8 We present here a novel type of BODIPY oligomer, connected via N-bridges in a linear fashion (Figure 1B). Utilizing both symmetric and unsymmetric BODIPY monomers as building blocks has paved the way to selectively synthesize oligomers with various chain lengths.…”

“…Additionally, the chain length of these oligo-BODIPYs was extended using functionalized monomer Br−Ar-mono−Br and dimer Br−Ar-di (Scheme 1). In contrast to the aforementioned cyclic amine-linked examples, 8 we have focused on selectively synthesizing open-chained oligomers and addressing their specific properties. Variation of the BODIPY core has been shown to have a considerable effect on the respective reaction times and yields.…”

“…Nonetheless, attempts to oxidize the obtained oligomers via literature methods 5d−g,6,8 did not provide quinodiimine analogs as known for the cyclic derivatives. 8 In summary, we have successfully developed a method to access linearly amine-linked BODIPYs under Buchwald− Hartwig conditions. Terminal Br substituents allowed for elongation of the chain by two further BODIPY subunits.…”