Synthesis and Self-Organization of Zinc β-(Dialkoxyphosphoryl)porphyrins in the Solid State and in Solution

The first synthesis and self‐organization of zinc β‐phosphorylporphyrins in the solid state and in solution are reported. β‐Dialkoxyphosphoryl‐5,10,15,20‐tetraphenylporphyrins and their ZnII complexes have been synthesized in good yields by using Pd‐ and Cu‐mediated carbon–phosphorous bond‐forming r...

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Published in:Chemistry : a European journal 2012-11, Vol.18 (47), p.15092-15104
Main Authors: Vinogradova, Ekaterina V., Enakieva, Yulia Y., Nefedov, Sergey E., Birin, Kirill P., Tsivadze, Aslan Y., Gorbunova, Yulia G., Bessmertnykh Lemeune, Alla G., Stern, Christine, Guilard, Roger
Format: Article
Language:English
Subjects:
aggregation
Chemical Sciences
Crystallography, X-Ray
Metalloporphyrins - chemical synthesis
Metalloporphyrins - chemistry
Models, Molecular
Molecular Structure
phosphonates
porphyrins
self-organization
Solutions
transition metals
Zinc - chemistry
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Summary:The first synthesis and self‐organization of zinc β‐phosphorylporphyrins in the solid state and in solution are reported. β‐Dialkoxyphosphoryl‐5,10,15,20‐tetraphenylporphyrins and their ZnII complexes have been synthesized in good yields by using Pd‐ and Cu‐mediated carbon–phosphorous bond‐forming reactions. The Cu‐mediated reaction allowed to prepare the mono‐β‐(dialkoxyphosphoryl)porphyrins 1 Zn–3 Zn starting from the β‐bromo‐substituted zinc porphyrinate ZnTPPBr (TPP=tetraphenylporphyrin) and dialkyl phosphites HP(O)(OR)2 (R=Et, iPr, nBu). The derivatives 1 Zn–3 Zn were obtained in good yields by using one to three equivalents of CuI. When the reaction was carried out in the presence of catalytic amounts of palladium complexes in toluene, the desired zinc derivative 1 Zn was obtained in up to 72 % yield. The use of a Pd‐catalyzed CP bond‐forming reaction was further extended to the synthesis of β‐poly(dialkoxyphosphoryl)porphyrins. An unprecedented one‐pot sequence involving consecutive reduction and phosphorylation of H2TPPBr4 led to the formation of a mixture of the 2,12‐ and 2,13‐bis(dialkoxy)phosphorylporphyrins 5 H2 and 6 H2 in 81 % total yield. According to the X‐ray diffraction studies, 1 Zn and 3 Zn are partially overlapped cofacial dimers formed through the coordination of two Zn centers by two phosphoryl groups belonging to the adjacent molecules. The equilibrium between the monomeric and the dimeric species exists in solutions of 1 Zn and 3 Zn in weakly polar solvents according to spectroscopic data (UV/Vis absorption and NMR spectroscopy). The ratio of each form is dependent on the concentration, temperature, and traces of water or methanol. These features demonstrated that zinc β‐phosphorylporphyrins can be regarded as new model compounds for the weakly coupled chlorophyll pair in the photosynthesis process. Metal‐mediated CP bond‐forming reactions were successfully applied to the synthesis of β‐(dialkoxyphosphoryl)porphyrins for the first time. An unusual one‐pot sequence involving consecutive reduction and phosphorylation of H2TPPBr4 (TPP=tetraphenylporphyrin) led to the formation of bis(dialkoxy)phosphorylporphyrins in good yields (see figure). According to X‐ray studies, the zinc β‐phosphorylporphyrinate complexes exist as cofacial dimers in the solid state.
ISSN:0947-6539
1521-3765
DOI:10.1002/chem.201202596