Nuclear magnetic resonance study of the association of porphyrins in chloroform solution. Mesoporphyrin IX dimethyl ester and its nickel chelate
The proton nmr spectra of chloroform solutions of mesoporphyrin IX dimethyl ester and its nickel chelate exhibit an appreciable concentration dependence, all peaks shifting downfield upon dilution. This dilution shift is greater for the nickel chelate. The spectra of both porphyrins exhibit additional fine structure at higher concentrations. These results are interpreted in terms of porphyrin association with equilibrium between monomer and dimer forms. In the dimer two porphyrin molecules are stacked one above the other with the planes of the molecules parallel and separated by 10.0 A in the mesoporphyrin and 7.9 A in the chelate. In the nickel chelate, association is enhanced by the slight affinity of the nickel for further coordination. The fine structure can be accounted for by a lateral displacement of one molecule in the dimer relative to the other. This displacement is caused by steric interference of the longer side chains. No attempt was made to calculate the magnitude of the displacement for either porphyrin.
- Research Organization:
- Bartlesville Petroleum Research Center, OK
- OSTI ID:
- 7305440
- Journal Information:
- J. Phys. Chem.; (United States), Journal Name: J. Phys. Chem.; (United States) Journal Issue: 2 Vol. 73:2; ISSN JPCHA
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
400201 -- Chemical & Physicochemical Properties
400301* -- Organic Chemistry-- Chemical & Physicochemical Properties-- (-1987)
CARBOXYLIC ACIDS
CHELATES
COMPLEXES
HETEROCYCLIC ACIDS
HETEROCYCLIC COMPOUNDS
MAGNETIC RESONANCE
NICKEL COMPLEXES
NUCLEAR MAGNETIC RESONANCE
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
PORPHYRINS
RESONANCE
STRUCTURAL CHEMICAL ANALYSIS
TRANSITION ELEMENT COMPLEXES