Structure and Function of Photoreactioncentre Chlorophyll

Katz, Joseph; Shipman, Lester L.; Norris, James R.

doi:10.1002/9780470720431.ch2

Cited by 7 publications

(1 citation statement)

References 60 publications

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“…This work was initially motivated by noting that closely coupled porphyrinic structures are involved in bacterial [5] and green plant photosynthesis [6]. Since that time, there have been a number of additional reports that involve the idea of electrostatically paired rings all without the participation of covalent interactions [7].…”

Section: Introductionmentioning

confidence: 99%

Solid-state porphyrin interactions with oppositely charged peripheral groups

Cheng

Oliver

et al. 2015

J. Porphyrins Phthalocyanines

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The crystallization and the crystal and molecular structure of a very slightly soluble electrostatically interacting pair of porphyrins is described. The tetra-anion 5,10,15,20-tetrakis-(4-sulfonatophenyl)-21,23H-porphyrin [H2TPPSO3]4− and the tetra-cation 5,10,15,20-tetra(N-methylpyridyl)21H,23H-porphyrin [H2TMePyP]4+ are found to form an alternating one-dimensional stack that is stabilised by electrostatic interactions between the porphyrin rings but also by π–π interactions between all substituted phenyl rings in the ensemble. The resulting interactions between the porphyrins is exceptionally tight.

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Section: Introductionmentioning

confidence: 99%

Solid-state porphyrin interactions with oppositely charged peripheral groups

Cheng

Oliver

et al. 2015

J. Porphyrins Phthalocyanines

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Steric interaction between the peripheral substituents of 10(S)‐chlorophyll derivatives and its conformational consequences: A proton magnetic resonance study

Hynninen

Lötjönen

1985

Magnetic Reson in Chemistry

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The improved methods developed recently for the preparation of lo(@-chlorophyll derivatives have permitted a detailed comparison of their conformations with those of the corresponding 10(R) derivatives, utilizing ' H NMR spectroscopy. Starting from the highly purified lo(@ derivative and following its conversion to the corresponding 10(R) form by repeated ' H NMR spectral measurements in acetone-&, reliable values for the differences in the chemical shifts (As) for each epimeric pair of compounds have been obtained. The relatively large A8 values (0.1-0.2ppm) observed for the P-l-CH,, P-H-2, P-3a-CH3 and 10b-CH3 signals were interpreted as indicating the proximity of the C-10 methoxycarbonyl group and the olefinic region of the phytyl group in the lo(@ derivatives. The proximity between these side-chains was considered to be derived principally from the three closely spaced carbonyls in the lo(@ derivatives. To miniize repulsion among the carbonyls, the C-7 and C-10 side-chains presumably assume conformations allowing maximal mutual distances for the carbonyls. As a compromise of various energetic factors, the phytyl group takes up a conformation where it bends to the right hand side of the macrocycle, or above rings V and III. This results in steric crowding between the olefinic region of the phytyl group and the C-10 methoxycarbonyl group. In addition, the other chemical shift increments show that the steric crowding between the bulky side-chains of the lo(@ derivatives increases the steric strain at the periphery of the macrocycle, relieved by pronounced conformational changes in rings IV and V and, to a lesser extent, also in the whole phorbin ring. The conformational differences were found to be larger for the magnesium-free epimers than for the chlorophylls. In the former case, they were also manifested by relatively large A6 values (0.1-0.5 ppm) for the pyrrole NH protons.

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High‐field proton NMR study of the liquid solution structure of monomeric bacteriochlorophyll a and chlorophyll a

Lötjönen

Michalski

Norris

et al. 1987

Magnetic Reson in Chemistry

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The 500 MHz proton spectra of monomeric bacteriochlorophyll a and chlorophyll a were recorded and assigned.The proton chemical shifts and proton-proton coupling constants were all determined except for the P-5 to P-15 phytyl side-chain protons. The conformational structures of the reduced rings and associated side-chains in these compounds were deduced from vicinal coupling constants. The reduced ring IV and the propionic ester side-chain in bacteriochlorophyll a and chlorophyll a have identical conformations which, in addition, are very similar to those reported previously for methyl pheophorbide a and pheophytin a. The reduced ring IV of bacteriochlorophyll a, which is attached to the phytyl side-chain, is more buckled than the other reduced ring (ring 11).

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Structure and Function of Photoreactioncentre Chlorophyll

Cited by 7 publications

References 60 publications

Solid-state porphyrin interactions with oppositely charged peripheral groups

Solid-state porphyrin interactions with oppositely charged peripheral groups

Steric interaction between the peripheral substituents of 10(S)‐chlorophyll derivatives and its conformational consequences: A proton magnetic resonance study

High‐field proton NMR study of the liquid solution structure of monomeric bacteriochlorophyll a and chlorophyll a

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