Naphtho[2,3- b]carbaporphyrins.

Area of Science:

• Organic Chemistry
• Materials Science
• Supramolecular Chemistry

Background:

• Carbaporphyrins are porphyrin analogs with a carbon atom replacing a nitrogen in the macrocycle.
• Extended π-conjugated systems are crucial for developing new functional materials with unique electronic and optical properties.

Purpose of the Study:

• To synthesize and characterize the first naphtho[2,3- b]-21-carbaporphyrin.
• To investigate the influence of a fused naphthalene unit on the spectroscopic and electronic properties of carbaporphyrinoids.
• To explore the reactivity and complexation behavior of this novel π-extended system.

Main Methods:

• Acid-catalyzed condensation of a benzo[ f]indane dialdehyde with a tripyrrane.
• Oxidation and subsequent functionalization reactions (protonation, chlorination, alkylation).
• Formation of metal complexes with Palladium(II) and Silver(III).
• UV-vis spectroscopy to analyze electronic transitions and aromaticity.

Main Results:

• Successful synthesis of naphtho[2,3- b]-21-carbaporphyrin with porphyrin-like UV-vis spectra (Soret band at 432 nm).
• Generation of mono- and di-protonated species, including a C-protonated dication.
• Formation of 21-chloro, 22-methyl derivatives, and metal complexes (Pd(II), Ag(III)).
• Observed spectral changes correlating with aromatic conjugation pathways through the naphthalene moiety in specific derivatives.

Conclusions:

• The fused naphthalene unit significantly influences the electronic structure and spectral properties of carbaporphyrinoids.
• Aromatic conjugation pathways dictate the observed UV-vis spectral shifts, especially in diprotonated and metal-complexed forms.
• This study expands the scope of carbaporphyrinoid chemistry and provides insights into structure-property relationships in extended π-systems.