Synthesis and Properties of meso-Arylated Corrphycenes

Parent, Unsubstituted Corrphycene: Synthesis and Properties

We report the synthesis of a porphyrin isomer that, until now, has only been obtained in the form of multiply substituted derivatives. Structural, spectral, and electrochemical characteristics of unsubstituted corrphycene (Cp) are described along with the data for its precursor, 11,18-di-tert-butylcorrphycene. Similar to porphine, Cp turns out to be a soft chromophore, characterized by very similar energy splittings between the pairs of frontier HOMO and LUMO orbitals. Magnetic circular dichroism spectra indicate that the splitting in the HOMO orbitals is larger than in the LUMO, opposite to the DFT predictions. Corrphycene exists in the form of a doubly degenerate trans tautomeric species. The two intramolecular H-bonds are not equivalent, which strongly suggests a stepwise mechanism of trans-trans conversion. Being a nearly perfect soft chromophore, Cp emerges as an attractive candidate for sensing changes in its environment.

Bis(naphthobipyrrolyl)methene-derived hexapyrrolic BODIPY as a single-molecule helicate with near-infrared emission

Helically twisted bis(naphthobipyrrolyl)methene-derived open-chain hexapyrroles have been synthesized as HCl salts and the corresponding BODIPY. Their solid-state structures elucidated by single-crystal X-ray diffraction analysis clearly showed the presence of intramolecular hydrogen bonds, which were concluded to play a pivotal role in stabilizing the twisted conformation. Both molecules were observed to be NIR active, with the BODIPY moiety emission extending beyond 800 nm.

Palladium-Catalyzed Cross-Coupling Reactions of Borylated Alkenes for the Stereoselective Synthesis of Tetrasubstituted Double Bond

The stereoselective formation of tetrasubstituted alkenes remains one of the key goals of modern organic synthesis. In addition to other methods, the stereoselective synthesis of tetrasubstituted alkenes can be achieved by means of cross-coupling reactions of electrophilic and nucleophilic alkene templates. The use of electrophilic templates for the stereoselective synthesis of tetrasubstituted alkenes has previously been described. Therefore, the present review summarizes the procedures available for the stereoselective preparation of tetrasubstituted alkenes using stable and isolable nucleophilic templates.

Chain Length Modulated Dimerization and Cyclization of Terminal Thienyl-Blocked Oligopyrranes

Oxidation of thienyl-blocked bilane and pentapyrrane afforded chain length dependent products of the symmetric dimer D1 and the thienyloligopyrrin-appended pentaphyrin analogue P2, respectively, with the latter formed by simultaneous dimerization and cyclization. Coordination of D1 and P2 with Cu(II) afforded di- and monometallic complexes D1-Cu2 and P2-Cu, respectively. These compounds exhibit distinct NIR absorption, with the absorption tail of D1-Cu2 extended to ca. 1900 nm despite its smaller conjugation framework than that of P2-Cu.

Homocarbaporphyrinoids: The m-o-m and p-o-p Terphenyl Embedded Expanded Porphyrin Analogues and Their RhI Complexes

Stable homocarbaporphyrinoids were successfully synthesized by incorporating the m-o-m and p-o-p terphenyl units into the porphyrin core. The distinct bonding modes of terphenyl in the macrocycle generated two structural isomers with two and four carbon atoms in the macrocyclic environment. The core was utilized to stabilize the Rh^I ion. The spectral and structural analyses revealed that the restricted (m-o-m) and allowed (p-o-p) conjugation in the macrocyclic core provide overall non-aromatic characteristics both to the free bases and their complexes.

Synthesis of Phlorin Analogues of Dithiacorrphycene and Their Use as Specific Chemodosimetric Sensors for Fe3+ 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.