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Structural Characterization of Artificial Self‐Assembling Porphyrins That Mimic the Natural Chlorosomal Bacteriochlorophylls c , d , and e
Author(s) -
Balaban Teodor Silviu,
LinkeSchaetzel Myriam,
Bhise Anil D.,
Vanthuyne Nicolas,
Roussel Christian,
Anson Christopher E.,
Buth Gernot,
Eichhöfer Andreas,
Foster Keir,
Garab Gyözö,
Gliemann Hartmut,
Goddard Richard,
Javorfi Tamas,
Powell Annie K.,
Rösner Harald,
Schimmel Thomas
Publication year - 2005
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.200400664
Subject(s) - bacteriochlorophyll , porphyrin , crystallography , chemistry , crystallization , cyclohexane , coronene , hydrogen bond , molecule , photochemistry , organic chemistry , pigment
We report two crystal structures of a synthetic porphyrin molecule which was programmed for self‐assembly. The same groups which ensure that bacteriochlorophylls c , d , and e can self‐assemble into the chlorosomal nanorods, the photosynthetic antenna system of some green bacteria, have been engineered into desired positions of the tetrapyrrolic macrocycle. In the case of the 5,15‐ meso‐ substituted anchoring groups, depending upon the concentration, by using the same crystallization solvents, either a tetragonal or a layered structure of porphyrin stacks were encountered. Surprinsingly, π–π interactions combined with extensive dispersive interactions, which also encompass cyclohexane, one of the crystallization solvents, win over putative hydrogen bonding. We are aware that our compounds differ considerably from the natural bacteriochlorophylls, but based upon our findings, we now question the hydrogen‐bonding network, previously proposed to organize stacks of bacteriochlorophylls. Transmission electron microscopy (TEM), atomic force microscopy (AFM), and small‐angle X‐ray scattering (SAXS) on various isomeric compounds support our challenge of current models for the chlorosomal antenna as these show structures, astonishingly similar to those of chlorosomes.