Dioxadiazuliporphyrin: a near-IR redox switchable chromophore

Area of Science:

• Organic Chemistry
• Supramolecular Chemistry
• Computational Chemistry

Background:

• Porphyrins and porphyrinoids are crucial macrocyclic compounds with diverse applications.
• Understanding the electronic and structural properties of novel porphyrinoid systems is essential for developing new functional materials.

Purpose of the Study:

• To synthesize and characterize dioxadiazuliporphyrinogen and its oxidized derivatives.
• To investigate the redox behavior and aromaticity of the dioxadiazuliporphyrin system.
• To explore the geometric and magnetic properties related to aromaticity and antiaromaticity.

Main Methods:

• Synthesis of dioxadiazuliporphyrinogen (7) and its oxidized forms (8 and 8(2+)).
• Solution-state characterization using UV-vis, 1H NMR, and 13C NMR spectroscopy.
• Solid-state structural analysis via single-crystal X-ray diffraction.
• Computational studies including density functional calculations and nucleus-independent chemical shifts (NICS).

Main Results:

• Successful synthesis and full characterization of dioxadiazuliporphyrinogen, dioxadiazuliporphyrin, and its dication.
• Dioxadiazuliporphyrin identified as a nonaromatic porphyrinoid, reversibly oxidizable to a cation radical and an aromatic dication.
• The dication can be described as a 21,23-dicarba-22,24-dioxaporphyrin with fused tropylium rings.
• Computational analysis provided insights into the aromaticity and antiaromaticity of the redox couple.

Conclusions:

• The study reports the synthesis and characterization of a novel dioxadiazuliporphyrinoid system.
• The redox chemistry reveals a transition from nonaromaticity to aromaticity upon oxidation.
• This work contributes to the understanding of structure-property relationships in porphyrinoids and their electronic characteristics.