Research and Development

@article{Guidote2014Electronic,

title = {Electronic Effects in Oxidation Reactions Utilizing Dinuclear Copper Complexes with the Bis[3-(2-hydroxybenzylideneamino)phenyl] Sulfone Ligand},

author = {Armando M. Guidote Jr. and Ronald L. Reyes and Riyo Kashihara and Yasuhiko Kurusu and Yoshiro Masuyama},

url = {https://kimika.pfcs.org.ph/index.php/kimika/article/view/180},

doi = {10.26534/kimika.v25i2.11-22},

issn = {2508-0911},

year  = {2014},

date = {2014-10-20},

journal = {KIMIKA},

volume = {25},

number = {2},

pages = {11-22},

abstract = {Copper acetate and the ligands bis[3-(3-tert-butyl-2-hydroxy-5-methoxybenzylidene-amino)phenyl] sulfone and bis[3-(3,5-di-tert-butyl-2-hydroxybenzylideneamino)phenyl] sulfone were reacted to form the complexes with 2:1 copper:ligand ratio, Cu2[B(t-Bu) (OMe)BAPS](µ-OCH3)2 (4) and with 2:2 copper:ligand ratio, Cu2[B(t-Bu)2BAPS]2 (5),  respectively.  Structures of 4 and 5 were determined based on IR, UV-Vis, and FAB-MS data in comparison with previously characterized related copper complexes. The two complexes 4 and 5 were utilized in the oxidation of the substrates 2,4- and 2,6-di-tert-butylphenol (dtbp) at -50C with H2O2 in CH2Cl2.  The coupling products are preferred in both cases. For 2,4-dtbp, yields of 4,600% and 7,200% of 3,3’,5,5’-tetra-tert-butyl-2,2’-biphenol were achieved with the use of 4 and 5, respectively. For 2,6-dtbp, yields of 1,900% and 400% of 3,3’,5,5’-tetra-tert-butyl-4,4’-biphenol were realized utilizing 4 and 5, respectively. These show that the methoxy groups activated the complex. Based on low temperature UV-vis results, a µ-η2:η2-peroxo or a µ-hydroperoxo intermediate was possibly formed by the reaction of 4 with the H2O2. This effected the oxidation of the 2,4- and 2,6-dtbp substrates but also resulted in the attack of other complexes which acted as substrates.  A proposed oxidation mechanism using complex 4 and related complexes is presented.},

keywords = {catalysis, copper complex, dinuclear, hydrogen peroxide, oxidation},

pubstate = {published},

tppubtype = {article}

}

@article{Guidote2004,

title = {Possible cobalt-cobalt bridging by a hemiacetal in the dinuclear cobalt complex bearing the ligand bis(3-(2-Pyridylmethyleneamino)phenyl) sulfone},

author = {Armando M. Guidote Jr. and Tomoko Imajo and Yoshiro Masuyama},

url = {https://kimika.pfcs.org.ph/index.php/kimika/article/view/142},

doi = {10.26534/kimika.v20i1.17-20},

year  = {2004},

date = {2004-01-01},

journal = {KIMIKA},

volume = {20},

pages = {17-20},

abstract = {A dinuclear cobalt complex bearing the ligand bis(3-(2-pyridylmethyleneamino)phenyl) sulfone (BPMAPS) was prepared. It is proposed that the structure of this is [Co2(BPMAPS)(m-OAcM)2(hemi-Et)]PF6 wherein the cobalt centers are bridged by two carboxylato groups in m-fashion and a hemiacetal with an ethoxy group (hemi-Et). This proposal is based on the similarity of the FT-IR, UV-Vis, and FAB-MS results with the crystallographically characterized dinuclear manganese complex [Mn2(BPMAPS)(m-OAc)2(hemi-Me)]PF6, and elemental analysis results.},

keywords = {cobalt, complex, dinuclear, synthesis},

pubstate = {published},

tppubtype = {article}

}

@article{Guidote2001,

title = {Synthesis, characterization and reactivity of a series of dinuclear copper complexes bearing the ligand bis[3-(2-hydroxybenzylideneamino)phenyl] sulfone and derivatives},

author = {Armando M. Guidote Jr. and Ken-ichi Ando and Kazunori Terada and Yasuhiko Kurusu and Hirotaka Nagao and Yoshiro Masuyama},

url = {https://www.sciencedirect.com/science/article/abs/pii/S0020169301005898},

doi = {10.1016/S0020-1693(01)00589-8},

year  = {2001},

date = {2001-11-15},

journal = {Inorganica Chimica Acta},

volume = {324},

pages = {203-211},

abstract = {The ligands bis[3-(X-2-hydroxybenzylideneamino)phenyl] sulfones (X=none: BHBAPS, X=3-tert-butyl: BH(t-Bu)BAPS and X=3,5-dichloro: BHCl2BAPS) were prepared. These, together with Cu(OAc)2 were used in the syntheses of the dinuclear copper complexes Cu2(BBAPS)(μ-OMe)2 (1), Cu2[B(t-Bu)BAPS] (μ-OH)2 (2), and Cu2[BCl2BAPS] (μ-OMe)2 (3). Complex 1 was crystallographically characterized. The structures of 2 and 3 are similar to 1 by comparison of IR, UV–Vis, FAB-MS and elemental analyses results. Complexes 1–3 (1 mol%) were used in the oxidation of 2,4- and 2,6-di-t-butylphenol (dtbp) at −50 °C with H2O2. The results show that (1) the coupling products are preferred when CH2Cl2 is used; and (2) the quinone yield increases when THF is utilized. In CH2Cl2 with 2,4-dtbp, the yield of the coupling product based on the complex amount, is in the order 2, 1, and 3 with yields of 6300, 4700 and 200%, respectively. Low temperature UV–Vis results of the reaction of 1 with H2O2 showed the growth of peaks at 390 and 580 nm indicative of a μ-η2:η2-peroxo or μ-η1:η1-hydroperoxo intermediate. At −50 °C, this spectrum does not change. But when warmed to 0 °C, a spectrum similar to the original spectrum was obtained. This probably indicates hydrogen radical abstractions of the peroxo intermediate from solvents, and if excess H2O2 is present, the peroxo intermediate may again be formed. This reusability of the complex explains the high yield using 1 and 2.



The ligands bis[3-(X-2-hydroxybenzylideneamino)phenyl] sulfones (X=none: BHBAPS, X=3-tert-butyl: BH(t-Bu)BAPS and X=3,5-dichloro: BHCl2BAPS) were prepared. These, together with Cu(OAc)2 were used in the syntheses of the dinuclear copper complexes Cu2(BBAPS)(μ-OMe)2 (1), Cu2[B(t-Bu)BAPS](μ-OH)2 (2), and Cu2[BCl2BAPS](μ-OMe)2 (3). Complex 1 was crystallographically characterized. The structures of 2 and 3 are similar to 1 by comparison of IR, UV–Vis, FAB-MS and elemental analyses results. Complexes 1–3 (1 mol%) were used in the oxidation of 2,4- and 2,6-di-t-butylphenol (dtbp) at −50 °C with H2O2.},

keywords = {catalysis, copper complex, dinuclear, oxidation, schiff base type ligand},

pubstate = {published},

tppubtype = {article}

}

@article{Guidote2001b,

title = {Syntheses and characterization of homodinuclear manganese and cobalt complexes bridged by a hemiacetal or by an acetato group in a μ-(η2:η1) bridging mode},

author = {Armando M. Guidote Jr. and Ken-ichi Ando and Yasuhiko Kurusu and Hirotaka Nagao and Yoshiro Masuyama},

url = {https://www.sciencedirect.com/science/article/abs/pii/S0020169301002948},

doi = {10.1016/S0020-1693(01)00294-8},

year  = {2001},

date = {2001-03-07},

journal = {Inorganica Chimica Acta},

volume = {314},

pages = {27-36},

abstract = {The complex [Mn2(BPMAPS)(μ-OAc)2(hemi)]PF6 (1), where hemi is the hemiacetal group, methoxy(2-pyridyl)methoxo, was prepared from bis[3-(2-pyridylmethyleneamino)phenyl] sulfone (BPMAPS), 2-pyridinecarbaldehyde, and manganese(II) acetate in methanol. The complexes Mn2(BPMAPS)(μ-OAc)2(μ-1,1-OAc)(η1-OAc) (2) and Co2(BPMAPS)(μ-OAc)2-[μ-(η2:η1)OAc](η1-OAc) (3) were prepared from manganese(II) acetate and cobalt(II) acetate, respectively, with BPMAPS in methanol. All three complexes were characterized by elemental analysis, FT-IR, MS, UV–Vis spectroscopy, and X-ray crystallography. The manganese ions of complex 1 are bridged by a hemiacetal through the oxygen atom of the alkoxo with the nitrogen atom of the pyridine group coordinating to one of the manganese atoms. The metal ions of complexes 2 and 3 are bridged by acetato groups in μ-1,1 or μ-η2:η1 modes, respectively.},

keywords = {cobalt complex, dinuclear, manganese complex, schiff base type ligand},

pubstate = {published},

tppubtype = {article}

}