Porphyrins and metalloporphyrins

Marks (1969) has discussed the physical properties of tetrapyrroles and has presented infrared spectral data for porphyrin and heme esters in the 1800-1500 cm region as found by Falk and Willis (1951). (See Table 14.3.) 

The biological and chemical importance of metalloporphyrins has caused much interest in the nature of the metal-ligand linkage in such complexes. Fleischer (1970) has discussed certain structural properties of the porphyrin molecule necessary for understanding such physical properties as its solubility, magnetic susceptibility, and visible absorption, electron spin resonance (ESR), and NMR spectra. He has also 

Functional group Stretching frequency, cm Bending and general deformation 

Caughey et a/. (1966) have done infrared studies of a series of substituted deutero-porphyrins IX (LXXXIV) which had been obtained from protoporphyrin IX or its iron(III) chloride (protohemin). These investigations have permitted vibrational 

Absorption frequencies of solid rock-salt prism (cm ) 

A further series of complexes that has been suggested to intercalate is based on tetrakis(A/ methylpyridyl)porphyrin (R = 4-iV-Mepy)  

With respect to the details of intercalation of this porphyrin and the 4,7-diphenylphenanthroline complexes discussed earlier, some rotation of the pyridine and phenyl rings into the plane of the phenanthroline and porphyrin rings, respectively, must occur for maximum overlap and intercalation to occur. The 2-A-methylpyridyl porphyrin, in agreement with the expected larger steric restraint, does not react with DNA. Even full planarity of one 4-A-methylpyridyl group, however, will barely give the minimal surface area for good overlap. 

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Solvation effects and coordination properties of porphyrins and metalloporphyrins in solutions 98MI19. 

The high stability of porphyrins and metalloporphyrins is based on their aromaticity, so that porphyrins are not only most widespread in biological systems but also are found as geoporphyrins in sediments and have even been detected in interstellar space. The stability of the porphyrin ring system can be demonstrated by treatment with strong acids, which leave the macrocycle untouched. The instability of porphyrins occurs in reduction and oxidation reactions especially in the presence of light. The most common chemical reactivity of the porphyrin nucleus is electrophilic substitution which is typical for aromatic compounds. 

Isobacteriochlorins, since they are tetrahydroporphyrins, can be obtained by tetrahydrogena-tion of porphyrins and dihydrogenation of chlorins. However, alkali-metal reduction of porphyrins and metalloporphyrins always gives a mixture of chlorins, bacteriochlorins or isobacteriochlorins.14 The method of choice for the preparation of pure isobacteriochlorins, e.g. 2, is the diimide reduction of zinc(II) chlorins, e.g. l.15a,b... 

Fullerenes are spontaneously attracted to porphyrins and metalloporphyrins. The palladium-linked m-pyridyl dimer (shown in Figure 42) has a high binding constant in solution. Addition of C60 or C70 to solutions of these palladium-linked bis-porphyrins gave complexes that were chromatographically distinct from their individual components. This indication of tight binding was also seen in MALDI mass spectra.517... 

Quirke, J. M. Mass Spectrometry of Porphyrins and Metalloporphyrins. San Diego Academic Press, 2000. 

Buchler, J. W. Static coordination chemistry of metalloporphyrins. In Porphyrins and Metalloporphyrins, Smith, K. M., Ed. Elsevier Amsterdam, 1975, pp 157-231. 

For a review of absorption and emission spectroscopy of porphyrins and metalloporphyrins, see Gouterman, M. Optical spectra and electronic structure of porphyrins and related rings. In The Porphyrins Dolphin, D., Ed., Academic Press New York 1978, Vol. Ill, pp 1-165. 

Smegal, J. A. Hill,C. L. (1983). Journal ofthe American Chemical Society, 105,2920-2. Smith, K. M. Ed. (1975). Porphyrins and Metalloporphyrins. Elsevier, New York. 

Thermal Atropisomerization of Porphyrins and Metalloporphyrins in Homogeneous Solution... 

Beilstein Handbook of Organic Chemistry, E III/IV, Vol. 26, Springer Verlag, Heidelberg 1978, pp. 3243-3246 Stoll, A., Wiedemann, E. Fortschr. Chem. Org. Naturst. I, 1938, 159-253 Fischer, H., Stern, A. Die Chemie des Pyrrols, Akad. Verlagsges., Leipzig, 1940 Smith, K.M. (Ed.) Porphyrins and Metalloporphyrins, Elsevier, Amsterdam, 1975 (physical and chemical properties)... 

Ignarro, L. J., Ballot, B., and Wood, K. S. (1984a). Regulation of soluble guanylate cyclase activity by porphyrins and metalloporphyrins.). Biol. Chem. 259, 6201-6207. 

Karlin, K. D. Zuberbuhler, A. D. Formation, structure, and reactivity of copper dioxygen complexes, Bioinorganic Catalysis , 2nd edn. (Revised and Expanded) Eds. Reedijk, J. Bouwman, E. Marcel Dekker New York, 1999, pp. 469-534. Fukuzumi, S. Imahori, H. Biomimetic electron-transfer chemistry of porphyrins and metalloporphyrins, Electron Transfer in Chemistry , Vol. 2 Ed. Balzani, V. Wiley-VCH Verlag GmbH Weinheim, 2001, pp. 927-975. 

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