Customizing Photoredox Properties of PXX‐based Dyes through Energy Level Rigid Shifts of Frontier Molecular Orbitals

Abstract

Here we describe the synthesis of electron-rich PXX derivatives in which the energy levels of the excited states have been rigidly shifted through the insertion of imide groups. This has allowed the development of a new series of oxygen-doped photoredox-active chromophores with improved oxidizing and reducing properties. Capitalizing on the dehalogenation of organic halides as a model reaction, we could investigate the photooxidative and photoreductive potential of these molecules in model chemical transformations. Depending on the substrate, solvent and dye the reaction mechanism can follow different paths. This prompted us to consider the first chemoselective transformation protocol, in which two different C-Br bonds could be chemoselectively reacted through the sequential photoactivation of two different colorants.

Tailored Synthesis of N-Substituted peri-Xanthenoxanthene Diimide (PXXDI) and Monoimide (PXXMI) Scaffolds

“…1 H NMR ((CD3)2SO, 300 MHz): δ 10.46 (s, 2H), 8.33 (s, 2H), 8.28 (dd, 2H, J = 7.1 Hz), 7.58 (dd, 2H, J = 7.9 Hz), 7.42 (dd, 2H, J = 8.4 Hz), 4.10 -4.06 (m, 4H), 1.69 -1.64 (m, 4H), 1.33 -1.26 (m, 20H), 0.86 (t, 6H, J = 6.6 Hz). HRMS (MALDI-TOF): m/z [M + H] + Calcd for C40H45N2O6 649.3278; Found 649.3251.Characterization in accordance with data reported in the literature 10.…”

“…As depicted in the diagram, the N-substituents display very similar HOMO and LUMO energy levels, whereas only 2 Per has a significantly lowered LUMO level (Figures 3, S58 and S59). (10). c HOMO and LUMO energies are calculated from the respective halfwave potential by assuming that the formal potential of the ferrocene redox couple, taken as a reference, is at -5.1 eV vs. vacuum and following the formulae: EHOMO = E 1/2 ox,1 -5.1 (eV) and ELUMO = E 1/2 red,1 -5.1 (eV).…”

“…Characterization in accordance with data reported in the literature. 10 -2-(2-(2-(2-hydroxyethoxy)ethoxy)ethyl)-6-(2-hydroxynaphthalen-1-yl)-1Hbenzo[de]isoquinoline-1,3(2H)-dione 21 Teg . In a singleneck round-bottomed flask, DIPEA (108 mg, 0.84 mmol) was added to a suspension of dihydroxy-binaphthylanhydride 20 (150 mg, 0.42 mmol) and 2-(2-(2aminoethoxy)ethoxy)ethan-1-ol (94.0 mg, 0.63 mmol) in 1,4-dioxane (10 mL).…”

“…1 5, 153.5, 152.7, 138.7, 135.3, 135.2, 133.3, 132.9, 132.0, 131.8, 131.1, 129.5, 129.4, 128.7, 128.1, 127.9, 124.8, 124.5, 124.4, 124.1, 122.9, 122.9, 121.4, 118.2, 110.3, 21.3, 18.0, 17.9 N-octyl-3,4-peri-xanthenoxanthene-dicarboxylicimide 2 Oct , PXXMI. 10 In a single-neck round bottom flask, compound 21 Oct (120 mg, 0.25 mmol), pivalic acid (52.0 mg, 0.51 mmol) and CuI (146 mg, 0.77 mmol) were dissolved in DMSO (4 mL). The reaction mixture was heated at 120 °C under air for 5 hours.…”

Synthesis and Photodynamic Activity of <i>Peri</i>-xanthenoxanthene Derivatives

“…Therefore, researchers continue to search for more suitable photosensitizers. 7,8) Peri-xanthenoxanthene (PXX) derivatives are polycyclic aromatic compounds with strong fluorescence and good optical properties. With good charge transfer properties, thermal stability, and chemical stability, these compounds are often used as compositions of pigments, charge transfer complexes, and organic semiconductors in electronic devices.…”