Substituted amino-piperazine derivatives were synthesized and used as precursors for the preparation of a series of new organometallic Re(i) imine complexes with the general formula [(η-CHCH[double bond, length as m-dash]N-(CH)-Pz-R)Re(CO)] (Pz-R: -alkyl or aryl piperazine). The piperazine-based ligands were designed to be potential inhibitors of GSK-3β kinase. All the ligands and complexes were fully characterized and evaluated against the HT-29 and PT-45 cancer cell lines, in which GSK-3β plays a crucial role. In this context, we carried out biological evaluation using the MTT colorimetric assay. In terms of structure activity relationship, our findings indicated improved biological activity when aromaticity increased in the organic ligands (3d). In addition, the presence of the rhenium fragment in the imines (5a-d) leads to better activity with IC values in the range of 25-100 μM. In addition, our experimental studies were complemented by computational studies, where the volume and electrostatic surface of the organic ligands and organometallic compounds as well as their binding to the kinase protein are calculated.
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...
Cyrhetrenyl aldehyde derivatives [(η5-C5H4CHO)Re(CO)2PR3] with R = methyl (Me, 2a), phenyl (Ph, 2b), and cyclohexyl (Cy, 2c) were synthesized by a photochemical reaction from the starting material [(η5-C5H4CHO)Re(CO)3] (1) and the corresponding phosphines. The complexes were fully characterized by FT-IR, 1H, 13C and 31P NMR spectroscopy, elemental analysis and mass spectrometry. The molecular structures of 2a-c have also been determined. Electronic structure calculations by TD-DFT and electrochemical studies are in sound agreement with the effect of the substitution of one carbonyl group by a phosphine ligand. Additionally, the antiproliferative activity of complexes 1 and 2a-c was studied on the human cancer cell lines HT-29 and PT-45 using an MTT assay. Out of all new compounds, only the triphenylphosphine derivative 2b exhibited pronounced cytotoxic effects on both cell lines, being ca. 1.5 times more potent than cisplatin.
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