Substitution reactivity and structural variability induced by tryptamine on the biomimetic rhenium tricarbonyl complex
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Date
2021
Authors
Jacobs, Frederick J. F.
Venter, Gertruida J. S.
Fourie, Eleanor
Kroon, Robin E.
Brink, Alice
Journal Title
Journal ISSN
Volume Title
Publisher
Royal Society of Chemistry
Abstract
A series of seven fac-[Re(CO)3(5Me-Sal-Trypt)(L)] complexes containing tryptamine on the N,O 5-methylsalicylidene
bidentate ligand backbone and where L is MeOH, Py, Imi, DMAP, PPh3 coordinated to the 6th
position have been studied, including the formation of a dinuclear Re2 cluster. The crystallographic solid
state structures show marked similarity in structural tendency, in particular the rigidity of the Re core and
the hydrogen bond interactions similar to those found in protein structures. The rates of formation and
stability of the complexes were evaluated by rapid time-resolved stopped-flow techniques and the
methanol substitution reaction indicates the significant activation induced by the use of the N,O
salicylidene bidentate ligand as manifested by the second-order rate constants for the entering
nucleophiles. Both linear and limiting kinetics were observed and a systematic evaluation of the kinetics
is reported clearly indicating an interchange type of intimate mechanism for the methanol substitution.
The anticancer activity of compounds 1–7 was tested on HeLa cells and it was found that all compounds
showed similar cytotoxicity where solubility allowed. IC50-values between ca. 11 and 22 mM indicate that
some cytotoxicity resides most likely on the salicylidene–tryptamine ligand. The photoluminescence of
the seven complexes is similar in maximum emission wavelength with little variation despite the broad
range of ligands coordinated to the 6th position on the metal centre.
Description
Keywords
Chemistry, Radiopharmaceutical drug development, Rhenium tricarbonyl, Substitution reactivity, Tryptamine, Salicylidene photoluminescence, Cytotoxicity
Citation
Jacobs, F. J. F., Venter, G. J. S., Fourie, E., Kroon, R. E., & Brink, A. (2021). Substitution reactivity and structural variability induced by tryptamine on the biomimetic rhenium tricarbonyl complex. RSC Advances, 11, 24443-24455. https://doi.org/10.1039/d1ra03750a