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We report Cu, Fe, N‐doped carbon nanotubes, (Cu,Fe)−N−CNT, as electrocatalysts for the oxygen reduction reaction (ORR) in acidic media. (Cu,Fe)−N−CNT was prepared using a silica coating method in pyrolysis to minimize the formation of carbon‐coated metal oxide or carbide nanoparticles, which are known to be inactive for the H2O2 reduction. (Cu,Fe)−N−CNT shows a turnover frequency of 0.66 e− site−1 s−1 at +0.8 V vs. RHE and H2O2 yields of <1 % for the ORR with a utilization factor of active sites of 82 %. Kinetic analysis reveals that 4e− transfer rates for (Cu,Fe)−N−CNT are higher than those of a monometallic counterpart of Fe−N−CNT. In situ X‐ray absorption spectroscopy enables us to determine redox potentials: E°'(FeIII/FeII)=0.65 V vs. RHE and E°'(CuII/CuI)=0.45 V for (Cu,Fe)−N−CNT, and E°'(FeIII/FeII)=0.65 V for Fe−N−CNT. These results indicate that bimetallic doping into carbon nanotubes gives the effect on kinetic parameters but not on thermodynamic ones. In other words, there is no direct electronic interactions between the Cu and Fe active sites for (Cu,Fe)‐N‐CNT because such interactions should modulate their redox potentials. [ABSTRACT FROM AUTHOR]

Fe/N/C single‐atom catalysts containing Fe−Nx sites prepared by pyrolysis are promising cathode materials for fuel cells and metal‐air batteries due to their high oxygen reduction reaction (ORR) activities. We have developed iron complexes containing N2‐ or N3‐chelating coordination structures with preorganized aromatic rings in a 1,12‐diazatriphenylene framework tethering bromo substituents as precursors to precisely construct Fe−N4 sites in an Fe/N/C catalyst. One‐step pyrolysis of the iron complex with carbon black forms atomically dispersed Fe−N4 sites without iron aggregates. X‐ray absorption spectroscopy (XAS) and electrochemical measurements revealed that the iron complex with N3‐coordination is more effectively converted to Fe−N4 sites catalyzing ORR with a TOF value of 0.21 e site−1 s−1 at 0.8 V vs. RHE. This indicates that the formation of Fe−N4 sites is controlled by precise tuning of the chemical structure of the iron complex precursor. [ABSTRACT FROM AUTHOR]

Research has been conducted on mononuclear Ca(II) complexes with dihydrogen phosphate ligands. The formation of hydrogen bonds between amide and oxygen atoms of phosphate among acid, monoanion and dianion states and the properties of Ca-O(phosphate) bonds investigated via the use of X-ray analysis and IR and (super)1 H NMR spectroscopy are discussed.

The synthesis of polynuclear Ca(II)- and Na(I) phosphte complexes with two strategically oriented bulky amide groups, 2,6-(PhCONH)2C6H3OPO3H2 is detailed. X-ray crystallography showed that all the chemicals have an unsymmetrical legend position due to the bulky amide groups. A dynamic transformation of the Ca(II) zigzag-chain structure to the cyclic-octanuclear complex is induced by changing the coordination of DMF molecules, which cause reorganization of inter/intra molecular hydrogen bond network.

Research has been conducted on the mercury(II) complexes containing cholyl amide group. The preparation of the aqueous micellar solution is described.

The synthesis of a novel dinuclear calcium complex is reported. This new calcium complex, which was synthesized using a structural model of 8-coordinated Ca(II) ions set in the double calcium-binding site of thermolysin, has four NH...O hydrogen bonds set between the carboxylate oxygen anion and the amide NH. Two types of bridging coordination were observed at the carboxylate ligand to Ca (II).