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STERIC HINDRANCE IN PROPOSED PHOTOISOMERS OF BILIRUBIN
Author(s) -
Geddes A. J.,
Potterton Elizabeth,
Willis G.
Publication year - 1980
Publication title -
photochemistry and photobiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.818
H-Index - 131
eISSN - 1751-1097
pISSN - 0031-8655
DOI - 10.1111/j.1751-1097.1980.tb02550.x
Subject(s) - steric effects , chemistry , pyrrole , planar , stereochemistry , computational chemistry , crystallography , organic chemistry , computer graphics (images) , computer science
— Semi‐empirical potential energy calculations have been used to examine the stabilities of the proposed geometric isomers of bilirubin. The calculations show that for either of the dipyrrole moieties, the ‘anti‐E’ and ‘syn‐E’ planar conformations are sterically unacceptable. The most stable form of the E isomer has the two pyrrole rings almost at right angles and in this conformation there can be no π‐delocalisation between the rings.