15 research outputs found
Resonance Raman Interrogation of the Consequences of Heme Rotational Disorder in Myoglobin and Its Ligated Derivatives
Supersaturated Oxygen Emulsion for Topical Treatment of Corneal Injuries from Chemical Exposure
Coordination self-assembly through weak interactions in meso-dialkoxyphosphoryl-substituted zinc porphyrinates
International audienceThe self-assembly of seven zinc 10-(dialkoxyphosphoryl)-5,15-diarylporphyrinates Zn5-Zn11 containing different substituents at the phosphonate and aryl groups was investigated. Single crystals of Zn5-Zn9 complexes were grown under the same conditions and analyzed by X-ray structural analysis. A supramolecular self-assembly is observed in all crystals through weak coordinative bonding of the phosphoryl group of one porphyrin molecule to the zinc(II) ion of a second porphyrin molecule. The geometry of the porphyrin macrocycle is similar in all of the studied crystals and the central zinc atom in each case adopts a distorted tetragonal pyramidal environment. However, the Zn5-Zn7 porphyrins display a 1D polymeric structure while the Zn8 and Zn9 complexes exist as discrete cyclotetramers in the crystals. This data demonstrates that the non-coordinating meso-aryl substituents of meso-(dialkoxyphosphoryl)porphyrins influence their crystalline organization. A self-assembly of the Zn5-Zn11 complexes is also observed in toluene and chloroform solutions over a large temperature range (223-323K). According to NMR studies, the associates exhibit dynamic behavior. A well-defined supramolecular aggregate of complex Zn10 at 10-3 M in toluene and chloroform solutions was unambiguously characterized as a cyclotetramer [Zn10]4 by 1 H NMR spectroscopy at 223K. The structure of the Zn10 association in toluene and chloroform shows a concentration dependence. When a solution of Zn10 in toluene was diluted from 10-3 M to 10-5 M, the average number of molecules in the associated unit decreased to about two