ISSN:
0749-1581
Keywords:
Ring current shifts
;
Aggregates of oppositely charged porphyrins
;
Solution structure
;
1H NMR
;
Chemistry
;
Analytical Chemistry and Spectroscopy
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
The aggregation of the water-soluble porphyrins tetra(4-carboxyphenyl)porphyrin free base (H2TPPC), tetra(4-N-methylpyridyl)porphyrin free base (H2TMPyP) and their zinc derivatives (ZnTPPC and ZnTMPyP) was studied by 1H NMR and optical absorption spectroscopy. In the solvent H2O—CH3OH (4:1), mixing of the anionic H2TPPC or ZnTPPC with the cationic H2TMPyP or ZnTMPyP yields various types of “hetero” aggregates. Only H2TPPC forms “homo” aggregates in this solvent. Addition of 1 m KCl results in an increase in the aggregation of H2TPPC and also enhances the aggregation of ZnTPPC. The structures of the “hetero” aggregates are stacks of the oppositely charged porphyrins in an alternating order. However, when one of the constituents is H2TPPC, aggregates having structures of the “homo” type are also formed. The 1H NMR ring current shifts are accounted for by identical conformations of dimers, and dimer structures in trimers and higher aggregates of the “hetero” type.
Additional Material:
3 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/mrc.1260260214
