| 1. |
- Cao, Guanyue, et al.
(author)
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Porphyrindiene-Based Tandem Diels-Alder Reaction for Preparing Low-Symmetry pi-Extended Porphyrins with Push-Pull Skeletons
- 2022
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In: Journal of Organic Chemistry. - : AMER CHEMICAL SOC. - 0022-3263 .- 1520-6904. ; 87:14, s. 9001-9010
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Journal article (peer-reviewed)abstract
- Tandem Diels-Alder reactions of masked porphyrindienes (i.e., sulfolenoporphyrins) with benzoquinones and stilbenes, followed by aromatization, have been developed to load porphyrin with mixed annulation units (i.e., terphenyl and naphthoquinone), furnishing the low-symmetry pi-extended porphyrins (DxAy) with push-pull skeletons. All low-symmetrical chromophores display panchromatic absorption spectra, which look like a spectral combination of symmetrical congeners (D4/A4) in a certain ratio. Among them, tD2A2 with trans-arrangement of push/pull units possesses the largest maximum centered at 766 nm with the onset around 900 nm. The fusion of the electron-deficient naphthoquinone moiety on the porphyrin core results in the approximately quantitative regulation of the E-ox1 and HOMOs (i.e., 0.10-0.13 V increase for the E-ox1 and 0.14-0.16 eV decrease for the HOMOs per naphthoquinone unit). In brief, this work provides a new way to construct low-symmetry pi-extended porphyrins with tunable properties resorting to the ratios and locations of the annulated push-pull units.
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| 2. |
- Fu, Yating, et al.
(author)
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Rational Synthesis of 5,5,5-Tricyclic Fused Thia-heptaphyrin (1.1.1.1.1.1.0) From a Helical Oligopyrrin Hybrid
- 2020
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In: Chemistry - An Asian Journal. - : WILEY-V C H VERLAG GMBH. - 1861-4728 .- 1861-471X. ; 15:8, s. 1285-1289
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Journal article (peer-reviewed)abstract
- Oxidation of a thiophene-hexapyrrane hybrid S-P-6 afforded a stable conjugated open-chain thiaheptapyrrolic helix 1 with the terminal thiophene and confused pyrrole units lying at a long distance that is adverse for further cyclization. Chelation of 1 with copper(II) ion afforded 1-Cu, which exhibits more distant terminal units. Interestingly, further oxidation of 1 triggered an intramolecular C-N fusion reaction to afford a unique 5,5,5-tricyclic fused linear thiaheptapyrrin 2, with the two terminals positioned in proximity, which favors the oxidative ring-closure reaction to give a unique 5,5,5-tricyclic fused thiaheptaphyrin (1.1.1.1.1.1.0) 3 under air. The inner-fusion strategy for positioning the reactive sites in proximity to promote oxidative cyclization offers a new approach for constructing large porphyrinoids through conjugated oligopyrrins without the assistance of metal ions.
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| 3. |
- Ma, Wenjing, et al.
(author)
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Rational construction of perylenequinone annulated porphyrins via cycloaddition reactions
- 2024
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In: Dyes and pigments. - : ELSEVIER SCI LTD. - 0143-7208 .- 1873-3743. ; 227
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Journal article (peer-reviewed)abstract
- Acenequinone-fused porphyrins show remarkable long wavelength absorption, low-lying LUMO orbital and uniform pi,pi-stacking, enabling the potential applications as opto-electronic materials and catalysts. At present, the synthesis of large quinone fused porphyrins remains challenging. To address this, the cycloaddition reactions of naphthoquinone-fused porphyrin (Ni4NQ), followed by oxidative aromatization, have been employed. Through Diels-Alder reaction with perylenes in the presence of chloranil, a series of perylenequinone-fused porphyrins (1Ni-4Ni) have been synthesized with an overall yield above 70 %. Later, the tri-adduct 3Ni underwent 1,3-dipolar cycloaddition with nitrile oxide and the following DDQ oxidation to outcome the unsymmetrical tetra-adduct 5Ni. Although the peripheral perylenequinones fusion in 1Ni-4Ni has limited impact on the absorption with respect to the naphthoquinone-fused counterpart Ni4NQ, introduction of an isoxazole via 1,3-cycloaddition (5Ni) leads to a bathochromic Q band. This result has been rationalized by theoretical calculations. Additionally, the incorporation of perylenequinone units gives rise to intense intermolecular pi,pi-stacking and CH-pi interactions within the crystal packing. The self-assembly behavior using a good/bad solvent strategy are structural dependence. The tri-perylenequinone-fused porphyrins 3Ni formed spherical architecture, while tetraperylenequinone-fused porphyrin 4Ni afforded cubic or petal-type assemblies.
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