Synthesis of Phlorin Analogues of Dithiacorrphycene and Their Use as Specific Chemodosimetric Sensors for Fe 3+ Ions.

The first examples of stable phlorin analogues of dithiacorrphycene were synthesized by treating appropriate tetrapyrranes with two equivalents of trifluoroacetic acid in CH2 Cl2 followed by oxidation with p-chloranil. The oxidative coupling of tetrapyrrane resulted in the formation of two unexpected phlorin analogues of dithiacorrphycenes that differed from each other at the meso-sp3 -carbon, and the two macrocycles were easily separated and isolated by column chromatography. The novel macrocycles were confirmed by X-ray crystallography and characterized by HRMS, 1D and 2D NMR spectroscopy, absorption spectroscopy, cyclic voltammetry, and time-dependent DFT studies. X-ray structure analysis revealed the highly strained and distorted nature of the macrocycles. The macrocycles showed one ill-defined absorption band at λ≈315 nm and a broad band at λ≈530 nm. Because both macrocycles possess two thiophene and two pyrrole rings with one ionizable inner NH, the cation-sensing properties of the phlorin analogues of dithiacorrphycenes have been investigated. The phlorin analogues of dithiacorrphycenes act as specific chemodosimetric sensors for Fe3+ ions by converting phlorin analogues of dithiacorrphycenes into dithiacorrphycene.