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Noncovalent cofacial porphyrin dimers have attracted interest due to their potential use as host materials or catalysts. In this study, we introduce a novel coordination‐directed cofacial porphyrin dimer from a meso‐tetraphenylporphyrin derivative modified with 2,2′‐bipyridine moieties at the meta positions of the phenyl groups. Spectroscopic investigation has shed light on the binding processes and the structure of the dimer in solution in detail. Initial Zn2+ ion binding to the porphyrin hinders the subsequent Zn2+ binding and the binding of the second porphyrin. However, once the dimer is formed, additional Zn2+ binding is notably enhanced, resulting in a pronounced S‐shaped binding curve. The detailed structure of the dimer in solution was established based on UV‐vis spectroscopy, various 1H NMR spectroscopy techniques and mass spectrometry. Simulations of ring‐current‐induced chemical shift changes provided evidence for the face‐to‐face porphyrin structure with tetrahedral coordination of the bipyridine ligands. The X‐ray single crystal structure provided conclusive evidence for the structure of the face‐to‐face dimer, which remarkably resembles the model structure from the 1H NMR simulation. The stability of the dimer structure makes it promising for further exploration of this motif in developing new supramolecular structures and for their potential applications as host compounds and catalysts. [ABSTRACT FROM AUTHOR]

The Front Cover represents the coordination‐directed formation of face‐to‐face porphyrin dimers. Each dimer is chiral depending on the screw sense of the two porphyrin rings. The P‐ and M‐helical dimers alternate in the crystal structure. The wood blocks are educational toys designed to help children learn Japanese Hiragana letters while having fun. The letters read Po‐Ru‐Fu‐I‐Ri‐N Da‐I‐Ma‐A, corresponding to "porphyrin dimer" in English. More information can be found in the Research Article by J. Otsuki and co‐workers...By Joe Otsuki; Ken Sato and Kosuke SugawaReported by Author; Author; Author [Extracted from the article]

Self‐assembly of porphyrins is a fascinating topic, not only for mimicking chlorophyll assemblies in photosynthetic organisms, but also for the potential of creating molecular‐level devices. Herein, zinc porphyrin derivatives bearing a meta‐pyridyl group at the meso position were prepared and their assemblies studied in chloroform. Among the porphyrins studied, one with a carbamoylpyridyl moiety gave a distinct 1H NMR spectrum in CDCl3, which allowed the supramolecular structure in solution to be probed in detail. Ring‐current‐induced chemical‐shift changes in the 1H NMR spectrum, together with vapor‐pressure osmometry and diffusion‐ordered NMR spectroscopy, among other evidence, suggested that the porphyrin molecules form a trimer with a triangular cone structure. Incorporation of a directly linked porphyrin–ferrocene dyad with the same assembling properties in the assemblies led to a rare example of a light‐harvesting/charge‐separation system in which an energy gradient is incorporated and reductive quenching occurs. [ABSTRACT FROM AUTHOR]

Keywords: energy transfer; porphyrinoids; self-assembly; structure elucidation; zinc EN energy transfer porphyrinoids self-assembly structure elucidation zinc 3888 3888 1 02/26/21 20210224 NES 210224 B A light-harvesting antenna model b made of three mutually axially coordinated zinc porphyrin molecules is reported in this work. With an energy gradient incorporated, energy transfer only occurs from porphyrin molecules specializing in light absorption to a porphyrin molecule as a charge separation center. Cover Feature: A Light-Harvesting/Charge-Separation Model with Energy Gradient Made of Assemblies of meta-Pyridyl Zinc Porphyrins (Chem. Eur. J. 12/2021). [Extracted from the article]