Dioxabenzosapphyrin: A New Benzodifuran-Derived Sapphyrin Analogue

Abstract

The synthesis and characterization of a new sapphyrin analogue, dioxabenzosapphyrin, are reported. The benzodifuran moiety upon which this system is based leads to the incorporation of two oxygen atoms within the central macrocyclic core, thus replacing two protonated nitrogen centers found in normal pentaaza sapphyrin derivatives, including those derived from benzodipyrroles. As expected, the loss of these two NH hydrogen bond donor sites greatly reduces the anion affinity for the diprotonated form, even though the overall charge is the same as in the corresponding sapphyrins. Interestingly, dioxabenzosapphyrin, but not the corresponding all-aza systems, is found to bind neutral guests, such as phenol and 4-nitrophenol, albeit weakly. This latter finding highlights a potentially new application for core-modified expanded porphyrin derivatives, namely, as receptors for hydrogen bond donating neutral substrates.

Synthesis, Characterization, and Electrochemistry of Open‐Chain Pentapyrroles and Sapphyrins with Highly Electron‐Withdrawing meso‐Tetraaryl Substituents

“…[12] Since then, sapphyrins have remained at opic of high interest, [13][14][15][16] in part because of their potential applicationsi nt he area of photodynamic therapy and their structurals imilarity to the well-known porphyrin and corrole macrocycles, [10,11,[17][18][19][20][21] and in part because of their unique properties as ar eceptor of neutraland anionic substrates. [22][23][24][25][26][27][28][29] Al arge number of studies have characterizedd ifferent sapphyrind erivatives, including b-alkylateds apphyrins, [30][31][32][33] coremodified sapphyrins with heteroatoms (O, S, or Se), [34][35][36][37][38][39][40][41][42][43][44][45][46][47][48][49][50] Nfused/N-confused sapphyrins, [51][52][53][54] and meso-tetraaryl-substituted sapphyrins. [55]…”

A facile synthetic route to meso-tetraaryl substituted N-5 sapphyrins and first single crystal X-ray analysis confirming the pyrrole inverted structure

“…Most investigated sapphyrins have contained coremodified macrocycles with O, S or Se heteroatoms [19][20][21][22][23][24][25][26][27][28][29][30][31], but a few N-5 meso-tetraaryl-substituted sapphyrins have been isolated as side-products in the synthesis of porphyrins [32,33] or directly synthesized by oxidation of an open-chain pentapyrrole in trifluoroacetic acid (TFA)/I 2 in solutions of benzene or toluene [34][35][36][37].…”

Quantum chemical studies of porphyrin‐ and expanded porphyrin‐based systems and their potential applications in nanoscience. Latin America research review

“…However, the solvent used, CH 2 Cl 2 , is not appropriate to be directly used in physiological conditions. The study in aqueous medium has been explored by other groups …”