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International audience; We report a series of four cyclams and cross-bridged cyclams, N-functionalized by one hydroxyethyl arm, which may incorporate additional methyl(s) group(s). The Cu(II) and Zn(II) complexes of these ligands were synthesized and fully characterized. The investigation of the metal complexes in solid-state and in solution was carried via X-ray diffraction, NMR, EPR, absorption spectroscopy and DFT calculations. The influence of N-functionalization on their structural/stereochemical properties, electrochemical behavior and kinetic inertness was carefully studied and identified. N-Functionalization by a hydroxyethyl group did not influence importantly the stereochemical properties of the complexes. However, it stabilized the complexes kinetically and electrochemically. As for N-methylation, it induces significant distortion of the coordination geometry, decreasing the kinetic inertness of the complexes and stabilizing Cu+. Overall, this work expanded the family of cyclam and cross-bridged cyclam metal complexes and provides a detailed analysis of their structural features. The rather large body of data accumulated for this family of complexes provides opportunities to design systems with pre-determined properties for specific applications.

We present here a novel strategy based on the covalent grafting of a C-functionalized Ni–cyclam complex onto glassy carbon to achieve heterogeneous electrocatalytic CO2 reduction in neutral water at low overpotential (−500 mV vs. NHE), with moderate turnover number (TON = 454), high selectivity (85% CO produced) and good faradaic efficiency (56% CO). Direct comparison with the N-functionalized Ni–cyclam analogue highlights the benefits of this approach in terms of CO2 electroreduction.

We report a series of four cyclams and cross-bridged cyclams

We present here a novel strategy based on the covalent grafting of a

International audience; Herein, we report a comprehensive coordination study of the previously reported ligands cyclam, CB-cyclam, TMC, DMC, and CB-DMC and of their C-functional analogues, cyclam-E, CB-cyclam-E, TMC-E, DMC-E, and CB-DMC-E. This group of ligands includes cyclam, cross-bridged cyclams, their di- or tetramethylated derivatives, and the analogues bearing an additional hydroxyethyl group on one β-N position of the ring. The Cu(II) and Zn(II) complexes of these macrocycles have been highlighted previously for the biological interest, but the details of their structures in the solid state and in solution remained largely unexplored. In particular, we analyzed the impact that adding noncoordinating N-methyl and C-hydroxyethyl functionalities has in the structures of the complexes. All the Cu(II) and Zn(II) complexes were synthesized and investigated using single crystal X-ray diffraction and NMR, electronic absorption, and EPR spectroscopies, along with DFT studies. Dissociation kinetics experiments in acidic conditions and electrochemical studies were also performed. Special attention was paid to analyze the different configurations present in solution and in the solid state, as well as the impact of the C-appended hydroxyethyl group on the coordination behavior. Various ratios of the trans-I, trans-III, and cis-V configurations have been observed depending on the degree of N-methylation and the presence of the ethylene cross-bridge.

Herein, we report a comprehensive coordination study of the previously reported ligands

Herein, we report a comprehensive coordination study of the previously reported ligands cyclam, CB-cyclam TMC, DMC, CB-DMC, and of their C-functional analogues, cyclam-E, CB-cyclam-E, TMC-E, DMC-E and CB-DMC-E. This group of ligands includes cyclam, cross-bridged cyclams, their di- or tetramethylated derivatives and the analogues bearing an additional hydroxyethyl group on one β-N position of the ring. These Cu(II) and Zn(II) complexes of these macrocycles have been highlighted previously for the biological interest, but the details of their structures in the solid state and in solution remained largely unexplored.

Amyloid-β (Aβ) aggregation and metal ion dyshomeostasis are found to be pathological features upon the progress of Alzheimer's disease (AD). In addition, Aβ and metal ions are reported to interact with each other forming metal–Aβ complexes, which can affect the aggregation of Aβ and cause oxidative stress via the production of reactive oxygen species (ROS). To disrupt metal coordination to Aβ and control the reactivities of metal–Aβ, metal chelating agents have been tested. Herein, a series of azamacrocyclic compounds with different properties of Cu(II) and Zn(II) binding and Aβ interaction were rationally selected under criteria based on structural and functional variations on the backbone of Cyclam. The series contains Cyclam, its N-methylated and cross-bridged (N-methylated or not) analogs, as well as their C-appended hydroxyethyl derivatives, and some of them have been newly synthesized. The reactivities of the cyclam derivatives towards the aggregation of metal–Aβ and the generation of ROS mediated by metal–Aβ were evaluated. Their modulative reactivities towards metal–Aβ could be achieved by generating a ternary complex with metal–Aβ and chelating the metal ion from metal–Aβ. Moreover, the toxicity induced by metal–Aβ in living cells was alleviated by the cyclam derivatives capable of regulating metal–Aβ aggregation and metal–Aβ-triggered ROS formation. Overall, our studies illustrate new examples of azamacrocyclic metal chelators that alter the interactions between metal ions and Aβ and subsequently modify the reactivities of metal–Aβ, with an indication of how the slight structure–property difference can influence such effects of small molecules.