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Synthesis, Structure, and Physicochemical Properties of Doubly Fused Phenoxazine‐Embedded Dithiasapphyrins

Year: 2026

Type: article

Abstract: Herein, we report the synthesis of a new class of doubly fused phenoxazine‐embedded dithiasapphyrins via (3 + 2) condensation of an appropriate phenoxazine‐based tripyrrane with bithiophene diol in CH 2 Cl 2 under BF 3 ·OEt 2 ‐catalyzed conditions. Single‐crystal X‐ray diffraction analysis of one representative macrocycle revealed an unusual structural rearrangement involving inversion of the two thiophene rings of the bithiophene unit, followed by fusion of the inner thiophene carbon atoms with adjacent pyrrolic nitrogen atoms to generate two tripentacyclic fused rings within the dithiasapphyrin framework. The resulting macrocycle adopts a highly distorted conformation, with the phenoxazine unit deviating by 66.97° from the mean plane defined by the four meso ‐carbon atoms. These doubly fused phenoxazine‐embedded dithiasapphyrins exhibit intense panchromatic absorption across the UV–visible region with pronounced bathochromic shifts relative to their previously reported phenothiazine‐fused analogues. Protonation with TFA further extends the absorption profile into the UV–visible‐near‐infrared region, affording strongly red‐shifted diprotonated species. Electrochemical studies revealed that the phenoxazine‐fused macrocycles are more electron‐rich than the corresponding phenothiazine derivatives. Density functional theory and time‐dependent density functional theory studies support the experimental observations.

Source: European Journal of Organic Chemistry

DOI: 10.1002/ejoc.70805

Authors: Neha Tripathi, Mangalampalli Ravikanth

Institution: Indian Institute of Technology Bombay

Language: English

Topic: Porphyrin and Phthalocyanine Chemistry

Subfield: Materials Chemistry

Field: Materials Science

Domain: Physical Sciences

Open Access status: bronze

Funders: Arthritis National Research Foundation, Indian Institute of Technology Bombay

Award: G3477590278