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Formation of Fluorescent and Nonfluorescent Difluoroboron Complexes in the Reaction of BF 3 Etherate with 21H,24H‐Bilin‐1,19‐dione Derivatives
Author(s) -
Borle Francois,
Fehr Felix,
Nesvadba Petr,
Gossauer Albert
Publication year - 1997
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.1751-1097.1997.tb07953.x
Subject(s) - chemistry , moiety , chelation , fluorescence , pyrrole , biliverdin , ligand (biochemistry) , heteroatom , molecule , divalent , stereochemistry , medicinal chemistry , photochemistry , ring (chemistry) , heme , inorganic chemistry , organic chemistry , enzyme , biochemistry , physics , heme oxygenase , receptor , quantum mechanics
On reaction with BF 3 etherate, in the presence of base, bile pigments of the biliverdin and 2,3‐dihydrobiliverdin type form two kinds of difluoroboron chelates. In one of them, which displays intensive photoluminescence, the boron atom is complexed through the nitrogen atoms of the dipyrrin moiety of the ligand molecule. In the second type of chelates, which have been characterized in the present work for the first time, the boron atom is complexed through the nitrogen atoms of the pyrrole and one of the terminal lactam rings. These BF 2 complexes are devoid of manifest fluorescence. Their 1 H‐NMR spectra show clear through‐space 1 H‐ 19 T spin‐spin couplings that served for structure elucidation. Bile pigment analogs, in which the pyrrolic HN group has been replaced by N‐CH 3 or by divalent heteroatoms, such as an O or S atom, form only the latter type of BF 2 chelates.