Novel organometallic chalcones functionalized with a crown ether fragment as optical ion chemosensors

Abstract

We previously reported the synthesis and characterization of new organometallic chalcones derived from ferrocene, cyrhetrene and cymantrene functionalized with a benzo‐15‐crown‐5 fragment. The ferrocene and cyrhetrene chalcones have been investigated as chemosensors for metal ions with optical response in acetonitrile. Several metal ions were selected considering the diameter of the cavity and the charge‐to‐radius ratio of the cation. The stoichiometry of the complexes was determined using Job's method. It was found that Na+ and Ca2+ complexes have a 1:1 stoichiometry while a 2:1 (metaloligand‐to‐cation) stoichiometry was determined for Ba2+ and Pb2+ complexes. The association constants were calculated according to the stoichiometry of the complex and the results showed that they are directly affected by the electron‐withdrawing nature of the organometallic fragment. Moreover, complexes of ferrocenyl chalcone have larger association constants than those of the cyrhetrenyl analogue. This experimental observation is consistent with the electronic properties of the ferrocenyl fragment.

A selective bis‐thiophene chalcone‐based spectrofluorimetric sensor for Fe3+

“…According to Job's plot, the binding stoichiometry between BTC and Fe 3+ was 1:1, and the fluorescence intensity peaked at a mole fraction of 0.5 ( Figure S8 , ESI). Fluorescence titration by the Benesi‐Hildebrand equation can be used to estimate the association constant between BTC and Fe 3+ [25]. $$$$ \frac{1}{\mathrm{I}-{\mathrm{I}}_0}=\frac{1}{{\mathrm{I}}_{\mathrm{max}}-{\mathrm{I}}_0}+\frac{1}{\left({\mathrm{I}}_{\mathrm{max}}-{\mathrm{I}}_0\right)\left[{\mathrm{Fe}}^{3+}\right]{\mathrm{K}}_{\mathrm{a}}} $$$$ …”

“…Job plot analysis was performed to determine the precise stoichiometry of the metal ion with the probe BTC [58]. We plotted the rela- Benesi-Hildebrand equation can be used to estimate the association constant between BTC and Fe 3+ [25].…”

“…This emission property explores the field of chalcone-based fluorescent probes. There are many examples where chalcones have been used as metal ion sensors [23][24][25][26][27][28][29]; however, examples of Fe 3+ sensors are still scarce [30][31][32][33] owing to their ease of interfering with other transition metal ions [34][35][36][37]. Hence, designing a highly selective and sensitive sensor for iron is still challenging.…”

Excited States versus Reaction Intermediates as Active Species in Photoinduced Redox Reactions of Cyrhetrenyl and Ferrocenyl Chalcones: A 351 nm Flash Photolysis Study

“…14 Also, organometallic chalcones have commanded interest as optical chemosensors in the field of metal ion recognition. 15,16 Notwithstanding the considerable interest on the biological activity of the chalcones, there has been a great paucity of mechanistic information on these compound photoredox reactions. In this context, some photochemical processes related to organic chalcones have been described previously in the literature.…”

“…Another example is a group of chalcones substituted with methylsulfonyl or trifluoromethyl moieties, which have been tested for their inhibitory activities on monoamine oxidase-B. , In the same context, organometallic chalcones have shown activity against some diseases; e.g., ferrocenyl–cymantrenyl heterobimetallic chalcones exhibit moderate antimalarial and antibacterial activities, while mononuclear cyrhetrenyl chalcones have shown to be active when tested in the evaluation of in vitro antimalarial activity . Also, organometallic chalcones have commanded interest as optical chemosensors in the field of metal ion recognition. , Notwithstanding the considerable interest on the biological activity of the chalcones, there has been a great paucity of mechanistic information on these compound photoredox reactions. In this context, some photochemical processes related to organic chalcones have been described previously in the literature. , Several authors have reported the photoinduced trans–cis isomerization of hydroxy-chalcones, in homogeneous and heterogeneous media, followed by a tautomerization reaction, which occurs in acid media. , Other photophysical processes related to organic chalcones have been identified using the flash photolysis technique, such as photoinduced proton transfer and triplet excited-state formation in a water–ethanol mixture .…”