ABSTRACT
10-Heterocorrole complexes with oxygen, sulfur, and selenium at positionâ 10 of the macrocycle and with the divalent ions of nickel, copper, and palladium were prepared and investigated. The focus was set on the size adaptation and matching mechanisms of cavity size versus ionic radius in corrole-type macrocycles. A full set of single-crystal X-ray analytical data revealed that in all but one case the N4 binding site of the ring-contracted tetrapyrrole was larger than necessary to bind the metal ion without deformation. In-plane size adaptation through M-N bond-length elongation by 2.5-3.2 % was effective, as well as pronounced out-of-plane ruffling of the macrocycle for those compounds with a more severe size mismatch. Such ruffling had been excluded for corroles previously, but is apparently the most efficient mechanism to adapt to small central ions.
ABSTRACT
The condensation of aldehydes with BODIPY (boron dipyrrin) luminophores was investigated. Formaldehyde can be used to connect two BODIPYs at each of the three pyrrolic C positions (α-, ß-, and ß'-positions) in a quick and highly selective manner, yielding new DYEmers (di- and oligomeric BODIPY derivatives) with varied photophysical properties. Benzaldehydes form DYEmers only at the ß- and the ß'-positions. For aliphatic aldehydes the DYEmer formation competes with the elimination of water from a proposed alcohol intermediate, leading to the formation of α- and ß-alkenyl-BODIPYs. 2-Phenylacetaldehyde and similar precursors exclusively yield elimination products. These acid-mediated transformations are valuable alternatives to the well-established, base-promoted Knoevenagel condensation protocol that is typically employed in the preparation of BODIPYs with near infrared (NIR)-shifted absorptions.
ABSTRACT
Cationic nickel(ii) complexes of two ring-contracted porphyrinoid ligands distantly related to the corrins were prepared by metal templated macrocyclisation. The compounds show reversible electron transfer processes and were found to be the first porphyrinoid-based catalysts for C-C cross-coupling.
ABSTRACT
The reaction of 5,10,15-trimesitylcorrole (H3 cor) with tungsten hexachloride and tungsten hexacarbonyl resulted in the unexpected formation of the 3,17-dichloro-5,10,15-trimesitylcorrole radical (H2 cor*) as an air-stable product. X-ray crystallography proved the planarization of the corrole radical structure, which was rationalized by the reduced steric hindrance of two versus three hydrogen atoms inside the N4 cavity. Although the aromaticity was lost, no specific changes in C-C or C-N bond distances could be observed. The regioselectivity of the two-fold chlorination is the result of the nucleophilic attack of chloride ions to an oxidized corrole macrocycle, and is supported by DFT results. The corrole radical acts as a dianionic ligand and allows the insertion of the divalent zinc(II) cation, which usually does not form neutral corrole complexes.
