Rational construction of perylenequinone annulated porphyrins via cycloaddition reactions

• 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.

Ämnesord

NATURVETENSKAP  -- Kemi -- Organisk kemi (hsv//swe)

NATURAL SCIENCES  -- Chemical Sciences -- Organic Chemistry (hsv//eng)

Nyckelord

Porphyrins; Perylene; Nitrile oxide; Diels-alder reaction; 3-dipolar cycloaddition; Assembly

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