Steffen Berg
University of Tromsø
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Featured researches published by Steffen Berg.
Journal of Inorganic Biochemistry | 2015
Jan Capar; Steffen Berg; Kolle E. Thomas; Christine M. Beavers; Kevin J. Gagnon; Abhik Ghosh
In spite of significant applications as starting materials for a variety of metallocorrole derivatives, free-base β-octabromo-meso-triarylcorroles continue to be viewed as inaccessible. The reasons range from the need for tedious column-chromatographic purification to limitations of the reductive demetallation protocol for selected systems. Here we report that column chromatography may be entirely avoided for a number of β-octabromo-meso-tris(p-X-phenyl)corrole derivatives, where X=CF3, NO2, F, H, CH3, and OCH3; instead, analytically pure products may be obtained by recrystallization from chloroform/methanol. In addition, we have presented an optimized synthesis of the heretofore inaccessible, sterically hindered ligand β-octabromo-meso-tris(2,6-dichlorophenyl)corrole, H3[Br8TDCPC], via reductive demetallation of the corresponding Mn(III) complex. With our earlier report of β-octabromo-meso-tris(pentafluorophenyl)corrole, H3[Br8TPFPC], a comprehensive set of optimized synthetic protocols are thus in place for a good number of β-octabromo-meso-triarylcorrole ligands. Furthermore, we have illustrated the use of these ligands by synthesizing the iron complexes Fe[Br8TDCPC]Cl and Fe[Br8TDCPC](py)2, of which the latter lent itself to single-crystal X-ray structure determination.
Journal of Inorganic Biochemistry | 2016
Jan Capar; Job Zonneveld; Steffen Berg; Johan Isaksson; Kevin J. Gagnon; Kolle E. Thomas; Abhik Ghosh
Abstract Copper undecaarylcorroles were found to undergo acid-induced demetalation with unusual ease under both reductive and nonreductive conditions. The resulting free-base undecaarylcorroles were found to be rather reactive, readily photooxygenating to yield 5/10-hydroxyisocorroles and open-chain tetrapyrroles. The use of nonreductive conditions led to 50-75% yields of undecaarylisocorroles, a new class of sterically hindered ligands, of which one proved amenable to single-crystal X-ray structural analysis. In one case, interaction of an undecaarylisocorrole with gold(III) acetate resulted in aromatization of the macrocycle and a gold undecaarylcorrole. The Au complex exhibited Au-N distances of 1.941(3)–1.965(3) A, and no significant nonbonded interactions involving the gold. The significant solubility of this complex in organic solvents, compared with the relative insolubility of gold β -octabromo- meso -triarylcorroles, appears to be related to the lack of aurophilic and metallophilic interactions.
Journal of Chemical Education | 2011
Steffen Berg; Abhik Ghosh
Archive | 2014
Abhik Ghosh; Steffen Berg
Journal of Chemical Education | 2013
Steffen Berg; Abhik Ghosh
European Journal of Inorganic Chemistry | 2015
Jeanet Conradie; Steffen Berg; Abhik Ghosh
Archive | 2014
Abhik Ghosh; Steffen Berg
Archive | 2014
Abhik Ghosh; Steffen Berg
Arrow Pushing in Inorganic Chemistry: A Logical Approach to the Chemistry of the Main-Group Elements | 2014
Abhik Ghosh; Steffen Berg
Arrow Pushing in Inorganic Chemistry: A Logical Approach to the Chemistry of the Main-Group Elements | 2014
Abhik Ghosh; Steffen Berg