The First X‐ray Characterized Monosubstituted Ferrocenyl Azacrown Chalcone: Focus on Its Calcium Interaction/Electrochemical Detection Studies

Abstract

The first X-ray characterization of an azacrown ferrocenyl chalcone [(C 5 H 5 )Fe(C 5 H 4 COCH=CHC 6 H 4 -p-aza-15-crown-5)] (2) is reported. Its cation electrochemical detection capabilities have been evaluated and its behaviour towards protonation and calcium addition has been thoroughly examined. The uncommon ligand-Ca 2+ interaction process involves three species of different stoichiometry in equilibrium in solution. Their association constants have been calculated. These species are formed by interaction of calcium with both the azacrown and CO functions of compound 2, as evidenced

Monosubstituted ferrocenyl chalcones: Effect of structural changes upon the ability to detect calcium by absorption spectroscopy

“…Let us consider now the origin of the H + source: Under our NMR experimental conditions, the salt to ligand ratio is below 15 equiv., and we have checked that there is no protonation reaction over a 48 h period [8]. In contrast, under our UV/vis conditions, the salt to ligand ratio is much higher.…”

“…Perchlorate salts are hazardous because of the possibility of explosion! Compounds 1-4 were prepared according to our published procedures [8].…”

“…Therefore, we have suspected the presence of a side-reaction leading to the formation of a by-product: the protonated homologue. We have previously shown elsewhere that adding HBF 4 to solutions of compounds 1-4 effectively leads to their N-protonated homologues [8]. Consequently, we investigated here the absorption behaviour of compounds 1-4 upon H + addition.…”

“…For comparison purpose, the absorption properties of these compounds were studied in CH 3 CN, as it was the case for their NMR and electrochemical properties [8]. The absorption spectrum of compound 1 (Fig.…”

“…In particular, in previous papers [8], we have established that the monosubstituted compounds (1-4) (Scheme 1) lead to peculiar and rather selective electrochemical detection of calcium. Their behaviour in presence of calcium salts has also been examined by NMR spectroscopy.…”