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Bifunctional Indenyl‐Derived Receptors for Fluoride Chelation and Detection
Author(s) -
Tirfoin Rémi,
Abdalla Joseph A. B.,
Aldridge Simon
Publication year - 2015
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.201501547
Subject(s) - bifunctional , chelation , fluoride , chemistry , receptor , combinatorial chemistry , organic chemistry , biochemistry , inorganic chemistry , catalysis
Anion receptors based on a [CpFe(indenyl)] scaffold offer the possibility for the incorporation of adjacent Lewis acidic functions onto a six‐membered carbocyclic framework, while at the same time retaining the colorimetric/electrochemical reporter mechanisms available to synthetically simpler ferrocene systems. Thus, [CpFe(indenyl)] systems featuring mutually ortho BMes 2 and PPh 2 Me + substituents (with either 4,5 or 5,6 regiochemistry) are accessible which are capable of cooperative fluoride ion fixation. Simultaneous binding at the borane and phosphonium centres can be established by spectroscopic, structural and computational approaches, and is responsible for the favourable thermodynamics associated with F − uptake. Thus, in contrast to simple BMes 2 systems, the binding of fluoride is found to be more favourable than the uptake of cyanide (which interacts only with the borane Lewis acid). Moreover, in the case of a 4‐(MePh 2 P)‐5‐(Mes 2 B)‐7‐Me‐indenyl derivative, fluoride chelation is signalled not only by a large cathodic shift in the Fe II /Fe III potential (>500 mV in THF), but also by a distinct colour change from green (for the free receptor) to maroon for the adduct.