Following the first suggestion of inherent molecular chirality in asymmetrically substituted subp... more Following the first suggestion of inherent molecular chirality in asymmetrically substituted subphthalocyanines by Torres and co-workers in 2000, elucidation of the relationship between structure and chirality has become an important issue. However, separation of the enantiomers has been prevented by the low solubility of the molecules synthesized to date, and it has not been possible to link the CD signs and intensities to their absolute structures. Recently, we observed that 1,2-subnaphthalocyanines possess two diastereomers with respect to the arrangement of the naphthalene moieties and that these novel chiral molecules exhibit moderate solubility in common organic solvents. This has enabled us to separate all of the diastereomers and enantiomers. The two diastereomers have been completely characterized by NMR spectroscopy and X-ray diffraction analysis. The absorption and magnetic circular dichroism spectra, together with theoretical calculation, reveal a small variation in the ...
The synthesis and investigation of the electronic properties of Co(II) and Fe(II)tetrakis(pyridin... more The synthesis and investigation of the electronic properties of Co(II) and Fe(II)tetrakis(pyridine-3-yloxy)phthalocyanines, as well as the respective quaternized complexes, are reported here. After quaternization reaction, the compounds showed increased solubility in water, and their aggregation equilibrium was analyzed by varying the solution concentration, pH, and composition. Cyclic voltammograms of the four compounds showed both metal and ring centered redox processes, with the former being highly sensitive to methylation of the pyridyl groups. The catalytic effect of the phthalocyanines adsorbed on glassy carbon electrodes in the oxygen reduction reaction (ORR) was investigated by cyclic voltammetry (CV) and rotating disk voltammetry (RDV). The highest catalytic activities were observed for the Fe(II) complexes in alkaline media, and a 2 + 2 mechanism, which consists of a first complete O2 to H2O2 process and a subsequent incomplete H2O2 to H2O process, is proposed.
The 3rd Georgian Bay International Conference on Bioinorganic Chemistry (also known as the Canadi... more The 3rd Georgian Bay International Conference on Bioinorganic Chemistry (also known as the Canadian Bioinorganic Conference, or CanBIC) was held in the dockside Charles W. Stockey Centre, in Parry Sound, Ontario, Canada from 31st May–4th June, 2011. This small conference attracted a stellar array of international speakers and poster-presenters in a wide range of fields related to metals in biological roles. Nagao Kobayashi (Tohoku University, Sendai, Japan), C. Frank Shaw III (Illinois State University, Normal, Illinois, USA) and Martin Stillman (Western Ontario, London, Ontario) were the international co-organizers, as for the 2nd conference held in 2009. Eight other colleagues joined them to serve as the International Organizing Committee: Juergen Gailer (Calgary), Serena DeBeer (Cornell), John Dawson (South Carolina), Ingrid Pickering (Saskatchewan), James Kincaid (Marquette, Milwaukee). Angela Rosa (Università della Basilicata, Italy), Stephen Sturzenbaum (King's College), and Stephen Ralph (Wollongong). The Local Organizing Committee was: Martin Stillman – Chair; Kelly Summers and Daisy Wong – Registration, Finances and Hall Managers; C. Frank Shaw III – Programme – Symposia; Tyler Pinter – Programme Book – Scheduling; Kalen Swanick – Catering; Duncan Sutherland – Abstracts Editor; Kelly Summers – Editor Poster Abstracts; Michael Tiedemann – Transportation and Poster Boards; Bill Browett – Photography; David Stillman – Technical Support; Anjan Mahrok and Tom Stockman – Student Participation; Jessica Schulz – Georgian Bay Day. CanBIC joins a select group of conferences focusing on the role of metals in biological systems. Metals are the key cofactors in 30% of all known proteins: for example, they are critical in muscle and synapse action and completely control respiration in all species. In short, metal-dependent biological chemistry is critical to all forms and phyla of life. The complexity of these systems, and sometimes
Journal of Porphyrins and Phthalocyanines, Oct 1, 1997
Cobalt octaethyltetrapyrazinoporphyrazine was synthesized and characterized by electronic absorpt... more Cobalt octaethyltetrapyrazinoporphyrazine was synthesized and characterized by electronic absorption and magnetic circular dichroism spectroscopy. These spectroscopies and molecular orbital calculations within the framework of the Pariser–Parr–Pople approximation revealed that the effective π-conjugation system of octaethyltetrapyrazinoporphyrazine is smaller than phthalocyanines. For the first time, the electrochemical behaviour of cobalt octaethyltetrapyrazinoporphyrazine irreversibly adsorbed onto a glassy carbon electrode as a surface modifier is reported. The cobalt derivative/glassy carbon electrode showed catalytic activity for oxygen reduction. Surprisingly, the peak potentials for oxygen reduction at this electrode coincide well with those where Co II is reduced to Co I over the whole pH range, indicating that the active species for dioxygen reduction is Co I rather than the Co II species. A possible mechanism for the electrocatalysis of oxygen is discussed.
The enantioselective Diels-Alder reaction of 1,2-dihydropyridines with aldehydes using an easily ... more The enantioselective Diels-Alder reaction of 1,2-dihydropyridines with aldehydes using an easily prepared optically active β-amino alcohol catalyst was found to provide optically active isoquinuclidines, an efficient synthetic intermediate of pharmaceutically important compounds such as oseltamivir phosphate, with a satisfactory chemical yield and enantioselectivity (up to 96%, up to 98% ee). In addition, the obtained highly optically pure isoquinuclidine was easily converted to an optically active piperidine having four successive carbon centers.
Three kinds of silicon phthalocyanine derivatives axially substituted by different groups were pr... more Three kinds of silicon phthalocyanine derivatives axially substituted by different groups were prepared and Singledecker-C[Formula: see text]PcSiCl2 (1a), Singledecker-C[Formula: see text]PcSi2(OH)4 (3a, b) and Doubledecker-(C[Formula: see text]PcSi)2Cl2 (4a, b) were obtained in order to investigate their mesomorphism for [Formula: see text] = 8(a) and 12(b). The mesomorphism was established by using polarizing microscopic observations, differential scanning calorimetric measurements, temperature-dependent electronic absorption spectra and temperature-dependent X-ray diffraction analysis. From the results, each of the derivatives, 1a, 3a, 3b, 4a and 4b showed columnar mesophases; 1a: Col[Formula: see text](P21/a), pseudo Col[Formula: see text] and Col[Formula: see text]; 3a, b: Col[Formula: see text](P21/a) and Col[Formula: see text]; 4a, b: two kinds of Col[Formula: see text]. Interestingly, each of the virgin samples of singledeckers, C8PcSiCl2 (1a), C8PcSi2(OH)4 (3a) and C8PcSi2(...
Following the first suggestion of inherent molecular chirality in asymmetrically substituted subp... more Following the first suggestion of inherent molecular chirality in asymmetrically substituted subphthalocyanines by Torres and co-workers in 2000, elucidation of the relationship between structure and chirality has become an important issue. However, separation of the enantiomers has been prevented by the low solubility of the molecules synthesized to date, and it has not been possible to link the CD signs and intensities to their absolute structures. Recently, we observed that 1,2-subnaphthalocyanines possess two diastereomers with respect to the arrangement of the naphthalene moieties and that these novel chiral molecules exhibit moderate solubility in common organic solvents. This has enabled us to separate all of the diastereomers and enantiomers. The two diastereomers have been completely characterized by NMR spectroscopy and X-ray diffraction analysis. The absorption and magnetic circular dichroism spectra, together with theoretical calculation, reveal a small variation in the ...
The synthesis and investigation of the electronic properties of Co(II) and Fe(II)tetrakis(pyridin... more The synthesis and investigation of the electronic properties of Co(II) and Fe(II)tetrakis(pyridine-3-yloxy)phthalocyanines, as well as the respective quaternized complexes, are reported here. After quaternization reaction, the compounds showed increased solubility in water, and their aggregation equilibrium was analyzed by varying the solution concentration, pH, and composition. Cyclic voltammograms of the four compounds showed both metal and ring centered redox processes, with the former being highly sensitive to methylation of the pyridyl groups. The catalytic effect of the phthalocyanines adsorbed on glassy carbon electrodes in the oxygen reduction reaction (ORR) was investigated by cyclic voltammetry (CV) and rotating disk voltammetry (RDV). The highest catalytic activities were observed for the Fe(II) complexes in alkaline media, and a 2 + 2 mechanism, which consists of a first complete O2 to H2O2 process and a subsequent incomplete H2O2 to H2O process, is proposed.
The 3rd Georgian Bay International Conference on Bioinorganic Chemistry (also known as the Canadi... more The 3rd Georgian Bay International Conference on Bioinorganic Chemistry (also known as the Canadian Bioinorganic Conference, or CanBIC) was held in the dockside Charles W. Stockey Centre, in Parry Sound, Ontario, Canada from 31st May–4th June, 2011. This small conference attracted a stellar array of international speakers and poster-presenters in a wide range of fields related to metals in biological roles. Nagao Kobayashi (Tohoku University, Sendai, Japan), C. Frank Shaw III (Illinois State University, Normal, Illinois, USA) and Martin Stillman (Western Ontario, London, Ontario) were the international co-organizers, as for the 2nd conference held in 2009. Eight other colleagues joined them to serve as the International Organizing Committee: Juergen Gailer (Calgary), Serena DeBeer (Cornell), John Dawson (South Carolina), Ingrid Pickering (Saskatchewan), James Kincaid (Marquette, Milwaukee). Angela Rosa (Università della Basilicata, Italy), Stephen Sturzenbaum (King's College), and Stephen Ralph (Wollongong). The Local Organizing Committee was: Martin Stillman – Chair; Kelly Summers and Daisy Wong – Registration, Finances and Hall Managers; C. Frank Shaw III – Programme – Symposia; Tyler Pinter – Programme Book – Scheduling; Kalen Swanick – Catering; Duncan Sutherland – Abstracts Editor; Kelly Summers – Editor Poster Abstracts; Michael Tiedemann – Transportation and Poster Boards; Bill Browett – Photography; David Stillman – Technical Support; Anjan Mahrok and Tom Stockman – Student Participation; Jessica Schulz – Georgian Bay Day. CanBIC joins a select group of conferences focusing on the role of metals in biological systems. Metals are the key cofactors in 30% of all known proteins: for example, they are critical in muscle and synapse action and completely control respiration in all species. In short, metal-dependent biological chemistry is critical to all forms and phyla of life. The complexity of these systems, and sometimes
Journal of Porphyrins and Phthalocyanines, Oct 1, 1997
Cobalt octaethyltetrapyrazinoporphyrazine was synthesized and characterized by electronic absorpt... more Cobalt octaethyltetrapyrazinoporphyrazine was synthesized and characterized by electronic absorption and magnetic circular dichroism spectroscopy. These spectroscopies and molecular orbital calculations within the framework of the Pariser–Parr–Pople approximation revealed that the effective π-conjugation system of octaethyltetrapyrazinoporphyrazine is smaller than phthalocyanines. For the first time, the electrochemical behaviour of cobalt octaethyltetrapyrazinoporphyrazine irreversibly adsorbed onto a glassy carbon electrode as a surface modifier is reported. The cobalt derivative/glassy carbon electrode showed catalytic activity for oxygen reduction. Surprisingly, the peak potentials for oxygen reduction at this electrode coincide well with those where Co II is reduced to Co I over the whole pH range, indicating that the active species for dioxygen reduction is Co I rather than the Co II species. A possible mechanism for the electrocatalysis of oxygen is discussed.
The enantioselective Diels-Alder reaction of 1,2-dihydropyridines with aldehydes using an easily ... more The enantioselective Diels-Alder reaction of 1,2-dihydropyridines with aldehydes using an easily prepared optically active β-amino alcohol catalyst was found to provide optically active isoquinuclidines, an efficient synthetic intermediate of pharmaceutically important compounds such as oseltamivir phosphate, with a satisfactory chemical yield and enantioselectivity (up to 96%, up to 98% ee). In addition, the obtained highly optically pure isoquinuclidine was easily converted to an optically active piperidine having four successive carbon centers.
Three kinds of silicon phthalocyanine derivatives axially substituted by different groups were pr... more Three kinds of silicon phthalocyanine derivatives axially substituted by different groups were prepared and Singledecker-C[Formula: see text]PcSiCl2 (1a), Singledecker-C[Formula: see text]PcSi2(OH)4 (3a, b) and Doubledecker-(C[Formula: see text]PcSi)2Cl2 (4a, b) were obtained in order to investigate their mesomorphism for [Formula: see text] = 8(a) and 12(b). The mesomorphism was established by using polarizing microscopic observations, differential scanning calorimetric measurements, temperature-dependent electronic absorption spectra and temperature-dependent X-ray diffraction analysis. From the results, each of the derivatives, 1a, 3a, 3b, 4a and 4b showed columnar mesophases; 1a: Col[Formula: see text](P21/a), pseudo Col[Formula: see text] and Col[Formula: see text]; 3a, b: Col[Formula: see text](P21/a) and Col[Formula: see text]; 4a, b: two kinds of Col[Formula: see text]. Interestingly, each of the virgin samples of singledeckers, C8PcSiCl2 (1a), C8PcSi2(OH)4 (3a) and C8PcSi2(...
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Papers by Nagao Kobayashi