Organometallic chalcone complexes functionalized with a macrocyclic fragment [( 5 -C 5 H 4 C(O)CH=CH-4-benzo-15-crown-5)MLn] (ferrocenyl, cyrhetrenyl, and cymantrenyl) have been synthesized. The complexes are characterized by IR spectroscopy, 1 H and 13 C NMR spectroscopies, elemental analyses, and HR-MS. The stereochemistry for the chalcone compounds was determined using the 1 H and 13 C NMR spectroscopy data, which indicated that they are isolated as a single isomer (E). In addition, the syntheses of the chalcone-imine derivatives are described, and they adopt an anti-(E,E) conformation in solution, confirmed by the X-ray crystal structures in the solid state. The UV-Visible and electrochemical behavior of the organometallic complexes are reported. Keywords: Organometallic chalcone and imine complexes, crown ether, crystal structures. examples of their application as chemosensors. Delavaux-Nicot et al. have investigated a series of ferrocenyl chalcones, mono and 1,1'-disubstituted, functionalized with an amine moiety or an aza-macrocycle. 13 These metallo-ligands have shown selectivity toward Ca 2+ and Ba 2+ in acetonitrile. Another important class of functionalized rhenium(I) complexes with aza-crown ether pendants, synthetized by Yam et al., exhibit a high specificity towardPb(II). 14 Previously, our research group reported the synthesis of new cyrhetrenyl tricarbonyl complexes functionalized with 4'-benzo-crown or 2-methyl-crown ether fragments, bridged by an imine linker. The cyclic voltammograms showed positive anodic waves arising from the Re(II)/Re(I) redox process (I). It was concluded that the size of the crown ether did not change the anodic potential significantly. Nevertheless, the metal centered redox processes of complexes that possess a methylene moiety were shifted to positive potentials compared to a benzo group. 15 In this work, we report the synthesis, X-ray structures and electrochemical and spectroscopic behaviour of new ferrocenyl, cyrhetrenyl and cymantrenyl complexes functionalized with 4'-benzo-15-crown-5 fragment. In addition we have included the synthesis of related species with a chalcone-imine as linker.2. Results and discussion. Synthesis of the organometallic chalcones 2-3.The compounds were synthesized following a procedure similar to that described for ferrocenyl and cymantrenyl chalcone derivatives. 11,16 It is based on the Claisen-Schmidt reaction involving the condensation of the organometallic ketones 1a-c and the corresponding crown ether or organic aldehydes Id-e (Scheme 1). Derivatives 2a-c and 3awere obtained by reaction of the corresponding precursors in the presence of NaOH and were dissolved in water/ethanol mixed solvent for greater solubility of the components. A modification of the experimental procedure was used for the preparation of the cyrhetrenyl derivative 3b. The carbanion containing solution was added dropwise to an ethanolic solution of terephthalaldehyde (Ie) over a period of 2 h. in order to control the proportion of nucleophile generated. The genera...

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Current selective modification methods, coupled with functionalization through organic or inorganic molecules, are crucial for designing and constructing custom-made molecular materials that act as electroactive interfaces. A versatile method for derivatizing surfaces is through an aryl diazonium salt reduction reaction (DSRR). A prominent feature of this strategy is that it can be carried out on various materials. Using the DSRR, we modified gold surface electrodes with 4-aminebenzene from 4-nitrobenzenediazonium tetrafluoroborate (NBTF), regulating the deposited mass of the aryl film to achieve covering control on the electrode surface. We got different degrees of covering: monolayer, intermediate, and multilayer. Afterwards, the ArNO2 end groups were electrochemically reduced to ArNH2 and functionalized with Fe(II)-Phthalocyanine to study the catalytic performance for the oxygen reduction reaction (ORR). The thickness of the electrode covering determines its response in front of ORR. Interestingly, the experimental results showed that an intermediate covering film presents a better electrocatalytic response for ORR, driving the reaction by a four-electron pathway.

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.