A new modified carbon paste electrode based on cyclam as a modifier was prepared for the determination of Co(Ⅱ) ions. The proposed electrode shows a Nernstian slope 28.4 mV per decade over a wide concentration range ...A new modified carbon paste electrode based on cyclam as a modifier was prepared for the determination of Co(Ⅱ) ions. The proposed electrode shows a Nernstian slope 28.4 mV per decade over a wide concentration range 5.0×10 -6_1.0×10 -1 mol/L of Co 2+ ions with detection limit 2.5×10 -6 mol/L. The sensor exhibits good selectivities for Co 2+ over a wide variety of other cations. It can be used as an indicator electrode in potentiometric titration of cobalt(Ⅱ) ions as well as in direct determination of cobalt(Ⅱ) ions in wastewater of acidic cobalt electroplating bath. The electrode shows Nernestian behavior in a solution of 25% ethanol.展开更多
The spectroscopic properties for a recently synthesized hetero-metallo- binuclear complex Ru(bpy)_2 (bpy-cyclam-Ni)^(4+)(3)and its related complexes 1 and 2 were investigated by UV-vis and emission spectral methods.A ...The spectroscopic properties for a recently synthesized hetero-metallo- binuclear complex Ru(bpy)_2 (bpy-cyclam-Ni)^(4+)(3)and its related complexes 1 and 2 were investigated by UV-vis and emission spectral methods.A drastic quenching of fluorescence from the Ru(bpy)_3^(2+) subunit by the covalently attached quencher sub- unit Ni(cyclam)^(2+) was observed for complex 3,and the mechanism was discussed.展开更多
We explore the detailed mechanism for the reduction reaction through systematic theoretical calculations,and the Ni-cyclam catalyst for the homogeneous CO_(2) reduction reaction exhibits high efficiency.We find that t...We explore the detailed mechanism for the reduction reaction through systematic theoretical calculations,and the Ni-cyclam catalyst for the homogeneous CO_(2) reduction reaction exhibits high efficiency.We find that the first hydrogen transfer step is the rate-determining step for the reaction.Our simulation results show that both the acidity of the environment and substituents play critical roles in the CO_(2) reduction reaction.The strong electron-withdrawing substituent perpendicular to the C atoms at the 5,6,12,14-position of cyclam decreases the energy barrier of the rate-determining step significantly.Moreover,we reveal the mechanism through density functional theory calculations,which exhibits the intra-molecular H-transfer feature and thus explains the extraordinary reactivity seen during the reaction in previous works.All the results ensure a good future for such series of Ni-cyclam catalysts.展开更多
Amyloid-β(Aβ)aggregation and metal ion dyshomeostasis are found to be pathological features upon the progress of Alzheimer’s disease(AD).In addition,Aβand metal ions are reported to interact with each other formin...Amyloid-β(Aβ)aggregation and metal ion dyshomeostasis are found to be pathological features upon the progress of Alzheimer’s disease(AD).In addition,Aβand metal ions are reported to interact with each other forming metal–Aβcomplexes,which can affect the aggregation of Aβand cause oxidative stress via the production of reactive oxygen species(ROS).To disrupt metal coordination to Aβand 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 Aβinteraction 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–Aβand the generation of ROS mediated by metal–Aβwere evaluated.Their modulative reactivities towards metal–Aβcould be achieved by generat-ing a ternary complex with metal–Aβand chelating the metal ion from metal–Aβ.Moreover,the toxicity induced by metal–Aβin living cells was alleviated by the cyclam derivatives capable of regulating metal–Aβaggregation and metal–Aβ-triggered ROS formation.Overall,our studies illustrate new examples of azamacrocyclic metal chelators that alter the interactions between metal ions and Aβand subsequently modify the reactivities of metal–Aβ,with an indication of how the slight structure–property difference can influence such effects of small molecules.展开更多
In this paper, we show that sweet quaternary ammonium, pyridinium, and imidazolium cyclamates are cheap, thermally stable, surface and biologically active ionic liquids, with potential application as feeding deterrents.
文摘A new modified carbon paste electrode based on cyclam as a modifier was prepared for the determination of Co(Ⅱ) ions. The proposed electrode shows a Nernstian slope 28.4 mV per decade over a wide concentration range 5.0×10 -6_1.0×10 -1 mol/L of Co 2+ ions with detection limit 2.5×10 -6 mol/L. The sensor exhibits good selectivities for Co 2+ over a wide variety of other cations. It can be used as an indicator electrode in potentiometric titration of cobalt(Ⅱ) ions as well as in direct determination of cobalt(Ⅱ) ions in wastewater of acidic cobalt electroplating bath. The electrode shows Nernestian behavior in a solution of 25% ethanol.
文摘The spectroscopic properties for a recently synthesized hetero-metallo- binuclear complex Ru(bpy)_2 (bpy-cyclam-Ni)^(4+)(3)and its related complexes 1 and 2 were investigated by UV-vis and emission spectral methods.A drastic quenching of fluorescence from the Ru(bpy)_3^(2+) subunit by the covalently attached quencher sub- unit Ni(cyclam)^(2+) was observed for complex 3,and the mechanism was discussed.
基金funded by the National Key R&D Program of China(2020YFA0406202)Natural Science Foundation of China,grant number No.22008006,22090042 and 21731001the Fundamental Research Funds for the Central Universities,grant number No.FRF-IDRY-20-005 and FRF-TP-20-077A1.
文摘We explore the detailed mechanism for the reduction reaction through systematic theoretical calculations,and the Ni-cyclam catalyst for the homogeneous CO_(2) reduction reaction exhibits high efficiency.We find that the first hydrogen transfer step is the rate-determining step for the reaction.Our simulation results show that both the acidity of the environment and substituents play critical roles in the CO_(2) reduction reaction.The strong electron-withdrawing substituent perpendicular to the C atoms at the 5,6,12,14-position of cyclam decreases the energy barrier of the rate-determining step significantly.Moreover,we reveal the mechanism through density functional theory calculations,which exhibits the intra-molecular H-transfer feature and thus explains the extraordinary reactivity seen during the reaction in previous works.All the results ensure a good future for such series of Ni-cyclam catalysts.
基金supported by the National Research Foundation of Korea(NRF)grant funded by the Korean government[NRF-2017R1A2B3002585(to M.H.L.)]the Institute for Basic Science(IBS-R010-D1)in Korea.
文摘Amyloid-β(Aβ)aggregation and metal ion dyshomeostasis are found to be pathological features upon the progress of Alzheimer’s disease(AD).In addition,Aβand metal ions are reported to interact with each other forming metal–Aβcomplexes,which can affect the aggregation of Aβand cause oxidative stress via the production of reactive oxygen species(ROS).To disrupt metal coordination to Aβand 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 Aβinteraction 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–Aβand the generation of ROS mediated by metal–Aβwere evaluated.Their modulative reactivities towards metal–Aβcould be achieved by generat-ing a ternary complex with metal–Aβand chelating the metal ion from metal–Aβ.Moreover,the toxicity induced by metal–Aβin living cells was alleviated by the cyclam derivatives capable of regulating metal–Aβaggregation and metal–Aβ-triggered ROS formation.Overall,our studies illustrate new examples of azamacrocyclic metal chelators that alter the interactions between metal ions and Aβand subsequently modify the reactivities of metal–Aβ,with an indication of how the slight structure–property difference can influence such effects of small molecules.
基金the National Science Centre (Poland) for financial support (7548/B/H03/2011/40)
文摘In this paper, we show that sweet quaternary ammonium, pyridinium, and imidazolium cyclamates are cheap, thermally stable, surface and biologically active ionic liquids, with potential application as feeding deterrents.
