Imidazoporphyrins as supramolecular tectons: synthesis and self-assembly of zinc 2-(4-pyridyl)-1H-imidazo[4,5-b]porphyrinate

摘要: 5,10,15,20-Tetramesityl-2-(4-pyridyl)-1H-imidazo[4,5-b]porphyrin (PyPor) bearing a pyridine donor site connected to the tetrapyrrolic macrocycle by rigid imidazole linker was prepared in high yield condensation of corresponding 2,3-dioxochlorin and 4-formylpyridine presence ammonium acetate. After insertion metal ion capable metal–ligand axial coordination, namely Zn(II), this compound afforded self-complementary porphyrin PyPorZn which suitable for self-assembly. In crystals, complex exists as zigzag coordination polymer formed through nitrogen atom zinc neighbouring molecule. The Zn atoms adopt distorted tetragonal pyramidal environment rings significantly deviate from orthogonal orientation mean N4 plane adjacent (the Cpara–NPy–Zn angle is equal 148°). This distortion analysed using DFT calculations 5,10,15,20-tetraphenylporphyrinate–pyridine (TPPZn–Py). energy geometry TPPZn–Py were calculated varying tilt ligand. change 180° 150° induces small increase (within 1.5 kcal mol−1) total complex. Such can be easily compensated intermolecular CH⋯H CH⋯π interactions crystals. self-assembly non-coordinating solvents also investigated NMR UV-vis spectroscopy. contrast nickel PyPorNi, 10−4 M solution toluene chloroform mixture short linear oligomers. These oligomers dissociate affording monomer species upon heating, dilution or addition substituting