Tailor-made aromatic porphyrinoids with NIR absorption

Synthesis of N-Heterocycle-Ligated Porphyrins Using Iodobenzene Diacetate Enabled Regioselective Cross-Dehydrogenation of Porphyrins and NH-Heteroaromatics

Preparation of diverse meso-functionalized porphyrins involves iodine(III)- and copper triflate-promoted dehydrogenative coupling of meso-free porphyrins and appropriate NH-free heterocycles. Reaction conditions involving the stable and recyclable iodobenzene diacetate reagent are compatible with a range of NH-free heterocycles (acridone, phenoxazine and phenothiazine, carbazole, β-carbolin triazoles, imidazole, pyrazole, indazole, and tetrazole) and porphyrins to access diversely functionalized A3B, A2BC, and A2B2 porphyrins in moderate to good yields. The prepared heterocycle-appended porphyrins exhibit modestly red-shifted Soret and Q bands in the absorption spectra.

Chemical Oxidation Induced Aromaticity Switching of E-Ethylene Bridged [38] Octaphyrin (1.2.1.0.1.2.1.0) with NIR Absorption

We report the syntheses, spectroscopic analyses, and solid-state structural evidence of a quasi-planar aromatic [38] E-ethylene bridged octaphyrin (1.2.1.0.1.2.1.0) exhibiting NIR absorption. The chemical oxidation using an appropriate oxidant led to unique π reconstruction via amine-imine conversion and/or C-oxygenation of the inverted thiophene rings resulting in weakly antiaromatic or nonaromatic [36] octaphyrins with preserved E-conformation of the ethylene moieties. The aromatic nature of the studied octaphyrins is supported by GIMIC calculations of the magnetically induced ring current density.

Copper complexation of rosarin: formation of bis-copper rosarin and mono-copper linear tridipyrrin complexes

A novel rosarin di-Cu complex 2Cu-1 and a linear six-pyrrolic mono-copper complex 1Cu-1 were synthesized using rosarin as the ligand. The molecular conformations of these complexes were confirmed by X-ray crystallography. The optical study of 1Cu-1 indicated NIR-II absorption due to the long six-pyrrolic ligand and the ICT effect. The 2Cu-1 complex exhibited a very narrow electronic reduction-oxidation gap of 0.50 eV, attributed to the antiaromatic characteristics of the rosarin ring. The first HER study of the di-copper rosarin complex 2Cu-1 indicated that the multi-metal poly-pyrrolic complexes are promising molecular hydrogen evolution reaction catalysts.

NIR Absorbing Aromatic E-Ethylene Bridged Hexaphyrins (2.1.1.2.1.1): Synthesis, Characterization, and Protonation Studies

Judicious syntheses, spectroscopic analyses, and solid state structural evidence of two structural variants (with planar geometry) of strongly aromatic hybrid [30] E-ethylene bridged hexaphyrins (2.1.1.2.1.1) exhibiting strong NIR absorption are reported. The induced correspondence of fused phenanthrene on the pyrrole moieties has led to a further red-shift of up to ∼45 nm in the neutral and protonated form of the macrocycles. The electronic nature and aromaticity of both hexaphyrins are fully supported by DFT calculations.

Fluoride ion Coordination-Induced Turn-On Fluorescence of Tailored N-Methyl N-Confused Tripyrromonomethene Analogues

Inorder to achieve striking compromise between flexibility and rigidity, two unprecedented highly air-stable N-methyl N-Confused tripyrromonomethene analogues in near quantitative yields have been synthesized by chloranil oxidation under aerobic condition....